Samacheer Kalvi Class 12 Bio Botany Solutions Chapter 1 Asexual and Sexual Reproduction in Plants

I. External fertilization	i. pollen grain
II. Androecium	ii. anther wall
III. Male gametophyte	iii. algae
IV. Primary parietal layer	iv stamens

(a) I-iv; II-i; III-ii; IV-iii
(b) 1-iii; II-iv; III-i; IV-ii
(c) I-iii; II-iv; III-ii, IV-i
(d) I-iii; II-i; III-iv; IV-ii
Answer: (c) I-iii; II-iv; III-ii, IV-i
In simple words: External fertilization happens in simple organisms like algae. Androecium refers to the stamens, which are the male parts of a flower. The male gametophyte is the pollen grain. The primary parietal layer eventually forms the anther wall.

🎯 Exam Tip: For matching questions, it's often helpful to first match the pairs you are most confident about, then use elimination for the remaining options.

 

Question 8. Arrange the layers of anther wall from locus to periphery
(a) Epidermis, middle layers, tapetum, endothecium
(b) Tapetum, middle layers, epidermis, endothecium
(c) Endothecium, epidermis, middle layers, tapetum
(d) Tapetum, middle layers endothecium epidermis
Answer: (d) Tapetum, middle layers endothecium epidermis
In simple words: The anther wall has several layers, starting from the inside and moving outwards. The order is tapetum (innermost), then middle layers, followed by endothecium, and finally the epidermis on the outside. This structure protects the pollen.

🎯 Exam Tip: Visualizing the cross-section of an anther and labeling its layers from inside to out is a very effective way to remember this order.

 

Question 9. Identify the incorrect pair
(a) sporopollenin – exine of pollen grain
(b) tapetum – nutritive tissue for developing microspores
(c) Nucellus – nutritive tissue for developing embryo
(d) obturator – directs the pollen tube into micropyle
Answer: (c) Nucellus – nutritive tissue for developing embryo
In simple words: The nucellus provides nutrients, but mainly for the megaspore and embryo sac, not directly for the developing embryo itself, which gets food from the endosperm. This makes the pair incorrect.

🎯 Exam Tip: Pay close attention to "incorrect" or "not true" in questions, as they require you to identify the false statement rather than the correct one.

 

Question. Assertion : Sporopollenin preserves pollen in fossil deposits. Reason: Sporopollenin is resistant to physical and biological decomposition.
(a) Assertion is true; reason is false
(b) Assertion is false; reason is true
(c) Both Assertion and reason are not true
(d) Both Assertion and reason are true
Answer: (d) Both Assertion and reason are true
In simple words: Both statements are correct. Sporopollenin is a very tough substance that protects pollen grains, allowing them to last for a long time as fossils because it resists breaking down.

🎯 Exam Tip: For assertion-reason questions, first evaluate if each statement is true, then determine if the reason correctly explains the assertion.

 

Question 11. Choose the correct statement(s) about tenuinucellate ovule
(a) Sporogenous cell is hypodermal
(b) Ovules have fairly large nucellus
(c) sporogenous cell is epidermal
(d) ovules have single layer of nucellus tissue
Answer: (a) Sporogenous cell is hypodermal and (d)ovules have single layer of nucellus tissue
In simple words: In a tenuinucellate ovule, the cell that will develop into the reproductive part is located just below the surface (hypodermal). Also, these ovules have only one thin layer of nucellus tissue.

🎯 Exam Tip: Remember the key characteristics of tenuinucellate and crassinucellate ovules, especially regarding the origin of the sporogenous cell and the nucellus thickness.

 

Question 12. Which of the following represent megagametophyte
(a) Ovule
(b) Embryo sac
(c) Nucellus
(d) Endosperm
Answer: (b) Embryo sac
In simple words: The megagametophyte is another name for the embryo sac, which is where the egg cell is formed inside the ovule. It is the female reproductive structure in flowering plants.

🎯 Exam Tip: Understand the different terms for the same structure, such as megagametophyte and embryo sac, to avoid confusion in exams.

 

Question 13. In Haplopappus gracilis, number of chromosomes in cells of nucellus is 4. What will be the chromosome number in Primary endosperm cell?
(a) 8
(b) 12
(c) 6
(d) 2
Answer: (c) 6 (3n)
In simple words: The nucellus cells have 4 chromosomes. Since the primary endosperm cell is triploid (3n), it will have three times the number of chromosomes from the nucellus, so \( 3 \times 2 = 6 \) chromosomes. This ensures the embryo has enough food.

🎯 Exam Tip: Always remember that the primary endosperm cell is triploid (3n), formed by the fusion of two polar nuclei (n+n) and one male gamete (n).

 

Question 14. Transmitting tissue is found in
(a) Micropylar region of ovule
(b) Pollen tube wall
(c) Stylar region of gynoecium
(d) Integument
Answer: (c) Stylar region of gynoecium
In simple words: Transmitting tissue is a special tissue found in the style of the flower's female part (gynoecium). It helps guide the pollen tube as it grows down towards the ovule.

🎯 Exam Tip: Associate transmitting tissue directly with its function of guiding the pollen tube through the style to the ovule.

 

Question 15. The scar left by funiculus in the seed is
(a) tegmen
(b) radicle
(c) epicotyl
(d) hilum
Answer: (d) hilum
In simple words: The hilum is a small scar on a seed that shows where it was attached to the plant's ovary. It's like the belly button of the seed.

🎯 Exam Tip: Understand the external structures of a seed like hilum, micropyle, and raphe, as their identification and function are often tested.

 

Question 16. A Plant called X possesses small flower with reduced perianth and versatile anther. The probable agent for pollination would be
(a) water
(b) air
(c) butterflies
(d) beetles
Answer: (b) air
In simple words: Plants with small flowers, tiny or absent petals (reduced perianth), and anthers that swing easily (versatile anthers) are usually pollinated by wind. Wind carries their pollen far and wide.

🎯 Exam Tip: Learn the characteristics of flowers adapted for different pollination agents (wind, water, insects, birds) to correctly identify the probable pollinator.

 

Question 17. Consider the following statement(s)
(i) In Protandrous flowers pistil matures earlier
(ii) In Protogynous flowers pistil matures earlier
(iii) Herkogamy is noticed in unisexual flowers
(iv) Distyly is present in Primula
Answer: (b) ii and iv are correct
In simple words: In protogynous flowers, the female part (pistil) becomes ready before the male part. Also, distyly, which means two different forms of flowers, is seen in plants like Primula.

🎯 Exam Tip: Differentiate clearly between protandry (male matures first) and protogyny (female matures first) and associate examples with each mechanism.

 

Question 18. Coelorhiza is found in
(a) Paddy
(b) Bean
(c) Pea
(d) Tridax
Answer: (a) Paddy
In simple words: The coelorhiza is a protective sheath covering the radicle (embryonic root) in monocot seeds, and it is found in plants like paddy. This structure helps the young root push through the soil.

🎯 Exam Tip: Memorize the specific examples of plants associated with particular botanical structures or processes.

 

Question 19. Parthenocarpic fruits lack
(a) Endocarp
(b) Epicarp
(c) Mesocarp
(d) seed
Answer: (d) seed
In simple words: Parthenocarpic fruits are special because they grow without fertilization, so they do not have any seeds inside. This is their main distinguishing feature.

🎯 Exam Tip: Understand that parthenocarpy is the development of fruit without fertilization, leading to seedless fruits, which is a key concept.

 

Question 20. In the majority of plants, pollen is liberated at
(a) 1 celled stage
(b) 2 celled stage
(c) 3 celled stage
(d) 4 celled stage
Answer: (b) 2 celled stage
In simple words: Most plants release their pollen when it has developed into a two-celled stage. This means it contains a generative cell and a vegetative cell, ready for pollination.

🎯 Exam Tip: Recognize the common developmental stage of pollen at which it is released from the anther, as this is a fundamental concept in plant reproduction.

 

Question 21. What is reproduction?
Answer: Reproduction is a natural process where living things create new individuals similar to themselves. It is very important for a species to continue existing, and it also allows for small changes (variations) in the young ones, which helps them survive better. This process ensures the continuity of life on Earth.
In simple words: Reproduction is when living things make babies or new life forms that are like them. It helps a species keep living and lets it change a little to survive better.

🎯 Exam Tip: When defining reproduction, emphasize both the creation of new individuals and its role in species survival and variation.

 

Question 22. Mention the contribution of Hofmeister towards Embryology.
Answer: Hofmeister made important contributions to the study of plant embryology:
• He worked on how embryos develop in flowering plants.
• He found out about the alternation of generations in plants, where plants switch between two life forms.
• He explained the structure of the pollen tetrad, which is a group of four pollen grains. These discoveries greatly advanced our understanding of plant life cycles.
In simple words: Hofmeister studied how plant embryos grow. He discovered how plants switch between different life stages and described what pollen looks like.

🎯 Exam Tip: When listing contributions, use bullet points for clarity and include specific discoveries or areas of study to show detailed knowledge.

 

Question 23. List out two sub-aerial stem modifications with example.
Answer: Sub-aerial stem modifications are special kinds of stems that grow partly above the ground and partly underground. Here are two examples:
a) **Runner:** (Example: Oxalis, Centella Asiatica)
• A runner grows horizontally along the surface of the soil.
• It has nodes where small leaves, buds, and roots grow.
• New runners grow from the side buds.
• The main plant makes many runners in all directions. Eventually, these break off and grow into new individual plants. This helps the plant spread quickly.
b) **Sucker:** (Example: Musa (banana), Chrysanthemum)
• A sucker grows horizontally under the soil for some distance.
• Then, it grows upwards at an angle and comes out of the ground. This helps plants like bananas spread and form new clumps.
c) **Stolon:** (Example: Strawberry, Vallisneria)
• Stolons develop from stems that are already underground.
• They grow outwards horizontally from the main plant.
d) **Offset:** (Condensed runners) (Example: Pistia, Eichhornia)
• Unlike runners, offsets have a bunch of leaves above the water and a cluster of roots below. These are like short, thick runners in water plants.
In simple words: Sub-aerial stems grow partly above and partly below ground. Runners spread on the soil surface (like Oxalis). Suckers grow underground then pop up (like banana plants). Stolons also grow horizontally from underground stems (like strawberry). Offsets are similar to runners but are short and thick, often seen in water plants.

🎯 Exam Tip: For questions asking for examples, make sure to provide both the type of modification and a correct plant name to earn full marks.

 

Question 24. What is layering?
Answer: Layering is a method of growing new plants from a parent plant without completely cutting off the stem first. In this technique:
• A part of the parent plant's stem is bent and buried in the soil while still attached to the main plant.
• Roots are encouraged to grow from the buried part of the stem.
• Once the roots have formed, the rooted part is cut from the parent plant.
• This newly rooted part is then planted as a new, independent plant. For example, Ixora and Jasminum can be grown this way. This method ensures the new plant has a strong root system before becoming independent.
In simple words: Layering is a way to make new plants by burying a stem while it's still attached to the parent, letting it grow roots, and then cutting it to become a new plant.

🎯 Exam Tip: Focus on explaining that layering involves root development on an attached stem before separation, distinguishing it from cutting.

 

Question 25. What are clones?
Answer: Clones are individual living things that are made through asexual reproduction. They are exact copies of their parent, meaning they look the same (morphologically identical) and have the exact same genetic information (genetically identical). This makes them very useful in agriculture for producing plants with desired traits. All the individuals from a single parent through asexual reproduction are called clones.
In simple words: Clones are new plants or animals made by asexual reproduction that are exactly like their parent, both in how they look and their genetic makeup.

🎯 Exam Tip: The key terms to include when defining clones are "asexual reproduction," "morphologically identical," and "genetically identical."

 

Question 26. A detached leaf of Bryophyllum produces new plants. How?
Answer: A detached leaf of Bryophyllum can produce new plants through a process called vegetative reproduction. Here's how it works:
• Bryophyllum plants reproduce new individuals from their leaves.
• The thick, fleshy leaf of Bryophyllum has small dips or notches along its edges.
• Special buds called adventitious buds grow in these notches. They are also known as epiphyllous buds.
• These buds then develop their own root system while still on the parent leaf.
• When the parent leaf eventually falls off and starts to decay, these well-developed buds become independent new plants. This is a fascinating example of natural cloning.
In simple words: Bryophyllum leaves have small buds on their edges. When the leaf falls, these buds grow roots and turn into new independent plants.

🎯 Exam Tip: Highlight the specific features of Bryophyllum leaves (notches, adventitious/epiphyllous buds) and the process of new plant development for a complete answer.

 

Question 27. Differentiate Grafting and Layering.
Answer: Here are the differences between Grafting and Layering, two methods of plant propagation:
**Grafting:**
1. In grafting, two different plant parts (a scion and a stock) are joined together to grow as one new plant. This combines the desirable traits of both.
2. The new plant will have characteristics from both parent plants, so some variation can be seen.
**Layering:**
1. In layering, only one parent plant is used to create a new plant, typically by rooting a stem while it is still attached.
2. No genetic variation is expected in layering; the new plant is an exact copy (genetically identical) of the parent plant.
In simple words: Grafting joins two different plant parts together, mixing their traits. Layering uses only one plant to make a new one that is exactly the same as the parent.

🎯 Exam Tip: Clearly state that grafting combines two plants and can introduce variation, while layering uses one plant and produces a clone.

 

Question 28. “Tissue culture is the best method for propagating rare and endangered plant species" Discuss.
Answer: Yes, tissue culture is indeed an excellent method for propagating rare and endangered plant species. This is because tissue culture, or micropropagation, uses the special ability of plant cells (totipotency) to grow into a whole plant from just a small piece of tissue or even a single cell in a lab. This method is highly effective for several reasons:
**Advantages:**
• Rare and endangered plants can be multiplied very quickly, helping to increase their numbers.
• Many plants with desired features can be produced in a short time.
• It produces genetically identical plants, ensuring the preservation of the original species' traits.
• This method can be done at any time of the year.
• Plants that do not produce viable seeds or are difficult to grow from seeds can be propagated.
• Meristem culture, a type of tissue culture, can produce plants free from diseases.
• Cells can be genetically changed or transformed, allowing for improvements in the species. This makes it a powerful tool for conservation.
In simple words: Tissue culture is great for rare plants because it can quickly make many exact copies from a tiny piece. It helps save plants that are hard to grow from seeds and can even make them disease-free.

🎯 Exam Tip: When discussing the importance of tissue culture, mention totipotency and list several advantages, such as rapid multiplication, genetic identity, and disease-free production, specifically in the context of rare species.

 

Question 29. Distinguish mound layering and air layering.
Answer: Here's a distinction between mound layering and air layering:
**Mound Layering:**
In mound layering, a flexible lower branch of a plant that still has leaves is bent down to the ground. A part of this stem is buried in the soil, while the tip of the branch remains exposed above the soil. After roots grow from the buried part of the stem, a cut is made to separate the new plant from the parent. This buried plant then grows into a new individual. This method is often used for plants with flexible stems.
**Air Layering:**
• In air layering, a ring of bark is removed from a branch (this is called girdling).
• Hormones that help root growth are applied to this exposed area.
• The girdled area is then covered with moist soil or sphagnum moss and wrapped in plastic to keep it moist.
• Roots emerge from the branch within 2-4 months.
• Once roots are strong enough, the branch is cut off from the parent plant.
• The rooted branch is then planted separately to grow into a new plant. This method is useful for branches that cannot be easily bent to the ground.
In simple words: Mound layering means burying a part of a low branch in soil to grow roots, then cutting it. Air layering means making roots on a branch still high on the tree by wrapping a cut part with wet soil.

🎯 Exam Tip: Clearly describe the key difference: mound layering involves ground contact, while air layering occurs on a raised branch, both aiming to root a stem before detachment.

 

Question 30. Explain the conventional methods adopted in the vegetative propagation of higher plants.
Answer: Conventional methods of vegetative propagation are traditional ways to grow new plants from parts of an existing plant, without using seeds. These methods are simple and effective. Here are some key conventional methods:
a) **Cutting** (Example: Hibiscus)
• In this method, parts of the plant, such as stems or leaves, are cut from the parent plant.
• The cut part is then placed in a suitable growing medium like soil or water.
• This part then develops roots and grows into a new, independent plant. This is a very common and easy way to multiply plants.
b) **Grafting** (Example: Citrus, Mango)
• Grafting involves joining two different plants together so they grow as one.
• The part of the plant that will become the top (stem and leaves) is called the scion.
• The part that will become the root system is called the stock, which is planted in the soil.
• The scion is attached to the stock, and they grow together as a single plant.
• There are five main types of grafting:
i) **Bud grafting:** A single bud from the scion is placed into a cut on the stock.
ii) **Approach grafting:** The cut surfaces of a scion (still attached to its parent) and a stock are tied together until they join, then the scion is detached.
iii) **Crown grafting:** A wedge-shaped scion is inserted into a split or cleft on the top of the stock.
iv) **Tongue grafting:** Both the stock and scion are cut with matching slanted cuts, fitted together, and tied.
v) **Wedge grafting:** A twig from the scion is inserted into a slot made in the stock.
c) **Layering**
• In layering, a stem of the parent plant is encouraged to develop roots while it is still attached to the main plant.
• Once roots have formed, the rooted part is cut and planted to grow as a new plant.
I) **Mound Layering:** A flexible branch is bent and buried in soil. Roots emerge from the buried stem, and it grows into a new plant.
ii) **Air Layering:**
• A nodal region of a branch is girdled (a ring of bark is removed).
• Rooting hormones are applied to this area.
• The area is covered with moist soil or moss to promote rooting.
• Roots emerge in 2-4 months.
• The rooted branch is then removed from the parent and grown separately. This ensures the plant gets established before being cut.
In simple words: Common ways to grow new plants without seeds include cuttings (like taking a piece of stem), grafting (joining two plants together), and layering (making a stem grow roots while still attached).

🎯 Exam Tip: Provide clear definitions and specific plant examples for each conventional method of vegetative propagation. For grafting, mention the different types to show comprehensive knowledge.

 

Question 31. Highlight the milestones from the history of plant embryology.
Answer: Plant embryology has a rich history with many important discoveries. Here are some key milestones:
1. **1682 – Nehemiah Grew:** He identified stamens as the male reproductive organ of a flower.
2. **1694 – R.J. Camerarius:** He described the structure of a flower, including the anther, pollen, and ovule, laying the groundwork for understanding plant reproduction.
3. **1761 – J.G. Kolreuter:** He provided a detailed explanation of how important insects are for pollination.
4. **1824 – G.B. Amici:** He discovered the pollen tube, which is crucial for fertilization.
5. **1848 – Hofmeister:** He described the structure of the pollen tetrad.
6. **1870 – Hanstein:** He described how embryos develop in specific plants like Capsella and Alisma.
7. **1878 – E. Strasburger:** He reported the phenomenon of polyembryony (the presence of more than one embryo in a single seed).
8. **1884 – E. Strasburger:** He also discovered the process of syngamy (fusion of gametes).
9. **1899 – S.G. Nawaschin and L. Guignard:** They independently discovered double fertilization, a unique process in flowering plants.
10. **1904 – E. Hanning:** He was the first to successfully initiate embryo culture.
11. **1950 – D.A. Johansen:** He proposed a classification system for embryo development.
12. **1964 – S. Guha and S.C. Maheswari:** They successfully raised haploid plants from Datura pollen grains.
13. **1991 – E.S. Coen and E.M. Meyerowitz:** They proposed the ABC model, which explains the genetics behind the formation and development of floral parts.
14. **2015 – K.V. Krishnamurthy:** He summarized the molecular aspects of reproductive development in flowering plants both before and after fertilization. These milestones show how our understanding of plant reproduction has grown over centuries.
In simple words: Many scientists helped us learn about plant embryos. People like Grew found male flower parts, Kolreuter saw how insects help pollinate, and Amici found pollen tubes. Later, Hofmeister looked at pollen, and Strasburger found many embryos and how egg and sperm join. Double fertilization was also discovered, and people started growing embryos in labs. More recently, genetic models were made to explain flower development.

🎯 Exam Tip: When listing historical milestones, try to include the scientist's name, the year, and a brief, accurate description of their key discovery. Grouping similar discoveries can also aid recall.

 

Question 32. Discuss the importance of Modern methods in reproduction of plants.
Answer: The ability of a plant cell to grow into a complete plant under the right conditions is called totipotency. This special feature of plant cells is very useful in farming, growing garden plants, and other industries to multiply plants.

• These methods allow for quick multiplication of desired plants.
• Plants with the exact same genetic makeup can be produced.
• Tissue culture can be performed in any season, making it very flexible.
• Plants that do not have good seeds or are hard to grow from seeds can still be propagated. This helps save rare plant types.
• Growing plants using meristem culture can produce plants that are free from diseases.
• Cells can also be changed genetically using these methods.

In simple words: Modern plant reproduction methods use a plant's ability to regrow from a single cell. This helps to quickly make many copies of plants, grow rare species, and even create disease-free plants at any time of year.

🎯 Exam Tip: When discussing the importance of modern plant reproduction methods, ensure you highlight benefits like genetic identity, rapid multiplication, and disease-free plant production.

 

Question 33. What is Cantharophily?
Answer: Cantharophily is a type of cross-pollination where flowers are pollinated by beetles. These beetles visit the flowers to feed on pollen or the juicy parts of the flower tissues. Beetle pollination is an ancient form of pollination.

• Plants that use this method of pollination include certain Nymphaea species (like water lilies), which are pollinated by Rhinoceros beetles.
• Other examples are the Giant Water lily, pollinated by Scarab beetles, and the Illicium plant, pollinated by Diptera flies.

In simple words: Cantharophily means pollination by beetles. Beetles help flowers reproduce by carrying pollen when they visit to eat the pollen or the flower's soft parts.

🎯 Exam Tip: Remember to name both the pollination type (Cantharophily) and the specific pollinator (beetles) when defining such terms, and provide an example if possible.

 

Question 34. List any two strategy adopted by bisexual flowers to prevent self-pollination.
Answer: Bisexual flowers have both male and female parts but often use strategies to avoid self-pollination, promoting cross-pollination instead. Two such strategies are:

1) Dichogamy: This happens when the male parts (anthers) and female parts (stigmas) of a flower mature at different times.

• Protandry: Here, the stamens (male parts) become ready before the pistil (female part) matures.
• Protogyny: In this case, the pistil (female part) matures earlier than the stamens (male parts).

2) Herkogamy: This refers to a physical arrangement of the stamens and stigmas that makes self-pollination impossible.

• For example, in Hibiscus flowers, the stigmas grow far above the stamens, preventing pollen from falling directly onto them.
• Even if a pollen grain from the same flower reaches the stigma, sometimes the flower has ways to stop it from growing, which is a genetic control.

In simple words: Bisexual flowers avoid pollinating themselves by making their male and female parts mature at different times (dichogamy) or by placing them far apart (herkogamy). These methods help them get pollen from other flowers instead.

🎯 Exam Tip: When explaining strategies to prevent self-pollination, clearly differentiate between temporal separation (dichogamy) and spatial separation (herkogamy), providing specific examples for each.

 

Question 35. What is the endothelium?
Answer: In plants belonging to the Asteraceae family (like sunflowers and daisies), the inner layer of the ovule's protective covering (integument) becomes specialized. This specialized layer helps to nourish the embryo sac. This nutritive layer is known as the integumentary tapetum or endothelium. It acts like a food source for the growing embryo.
In simple words: The endothelium is a special inner layer in some plant ovules that provides food for the developing embryo.

🎯 Exam Tip: Remember that the endothelium is a specialized nutritive layer of the integument, important for the embryo sac's nourishment, especially in Asteraceae.

 

Question 36. “The endosperm of angiosperm is different from gymnosperm". Do you agree? Justify your answer.
Answer: Yes, I agree that the endosperm of angiosperms is different from that of gymnosperms. This difference is mainly due to their formation and ploidy level. The endosperm is a nutritive tissue that supports the growing embryo.

Endosperm of Angiosperms:

1. It is a triploid (3n) tissue, meaning it has three sets of chromosomes.
2. It forms after fertilization through a process called triple fusion, where one male gamete fuses with the two polar nuclei.
3. This endosperm develops alongside the embryo and provides nutrition for it.

Endosperm of Gymnosperms:

1. It is a haploid (n) tissue, containing only one set of chromosomes.
2. It forms before fertilization from the female gametophyte.
3. In gymnosperms (like pine trees), the endosperm provides nutrition as starch and other stored food for the embryo, which also has many cotyledons.

In simple words: Yes, the endosperm in flowering plants (angiosperms) and non-flowering seed plants (gymnosperms) is different. In flowering plants, it has three sets of chromosomes and forms after fertilization to feed the baby plant. In gymnosperms, it has one set of chromosomes and forms before fertilization.

🎯 Exam Tip: When comparing angiosperm and gymnosperm endosperm, clearly state the differences in ploidy (triploid vs. haploid) and the timing of their formation (after vs. before fertilization).

 

Question 37. Define the term Diplospory.
Answer: Diplospory is a process where a diploid embryo sac is formed directly from the diploid mother cells without undergoing a regular meiotic (reductional) division. This means the embryo sac and the resulting embryo will have the same number of chromosomes as the parent plant, ensuring genetic identicalness. For example, this occurs in plants like Eupatorium.
In simple words: Diplospory is when a plant's embryo sac forms directly from its normal body cells without the usual chromosome halving process. This creates seeds that are genetically the same as the parent plant.

🎯 Exam Tip: The key points for Diplospory are that it forms a *diploid* embryo sac from *mother cells* without *meiosis*, leading to genetic similarity with the parent.

 

Question 38. What is polyembryony? How can it be commercially exploited?
Answer: Polyembryony is a condition where more than one embryo develops within a single seed. This can happen in several ways, leading to multiple seedlings from one seed.
Practical Applications (Commercial Exploitation):

• Seedlings that come from the nucellar tissue in citrus fruits (like oranges and lemons) are better clones for growing in orchards. This means they are genetically identical and have desired traits.
• Embryos produced through polyembryony are often free from viruses. This is a big advantage for growers because it helps to produce healthy plants. Using these virus-free embryos ensures that a disease doesn't spread through a whole crop.

In simple words: Polyembryony is when a seed has more than one baby plant inside. Farmers use this to grow many identical, healthy citrus trees or other plants, especially since these extra plants can be naturally free of viruses.

🎯 Exam Tip: When defining polyembryony, mention the presence of multiple embryos in a single seed. For commercial exploitation, focus on the production of genetically uniform and disease-free clones, especially for fruit crops.

 

Question 39. Why does the zygote divide only after the division of the Primary endosperm cell?
Answer: The zygote, which is the first cell of the embryo, begins to divide only after the Primary Endosperm Nucleus (PEN) has divided and formed the endosperm. This is because the endosperm's main role is to act as a nutritive tissue, providing food and energy for the developing embryo. By forming the endosperm first, the plant ensures that a reliable food source is available to support the zygote's growth and development into an embryo. It's a critical synchronization for successful plant reproduction.
In simple words: The baby plant's first cell (zygote) waits to divide until its food supply (endosperm) is ready. This ensures the baby plant has enough food to grow well right from the start.

🎯 Exam Tip: The key reason for delayed zygote division is to ensure the prior formation of the nutritive endosperm, which is essential for the embryo's sustained development.

 

Question 40. What is Mellitophily?
Answer: Mellitophily is a type of pollination specifically carried out by honeybees. The term "mellitus" comes from Latin and means honey or sweet, referring to the bees' attraction to nectar. Honeybees are among the most common and important pollinators in the insect world because they play a big role in plant reproduction by visiting many flowers to collect nectar and pollen.
In simple words: Mellitophily is when honeybees help flowers spread their pollen. Bees are very important for many plants to make seeds and fruits because they are attracted to the sweet nectar.

🎯 Exam Tip: When defining Mellitophily, clearly link it to pollination by honeybees and remember the Latin root "mellitus" (honey/sweet) to reinforce the connection to bees' foraging habits.

 

Question 41. "Endothecium is associated with dehiscence of anther” Justify the statement.
Answer: The statement is true because the endothecium plays a crucial role in the dehiscence (opening) of the anther, which releases pollen. The cells of the endothecium have special thickenings made of cellulose, sometimes also slightly lignified, on their inner (tangential) and radial walls. These cells are hygroscopic, meaning they can absorb water. As the anther dries, these hygroscopic cells lose water, causing them to shrink and create tension. However, the cells along the connecting part of the two sporangia (the pollen sacs) in an anther lobe do not have these thickenings. This specific region is called the stomium. The combination of the hygroscopic nature of the endothecium and the weaker stomium area causes the anther to split open at maturity, effectively releasing the pollen grains.
In simple words: The endothecium helps anthers open up to release pollen. It has special walls that shrink when dry, creating tension. This tension, along with a weaker part of the anther called the stomium, causes the anther to break open, letting the pollen out.

🎯 Exam Tip: To justify the role of endothecium in anther dehiscence, mention its hygroscopic nature, the cellulose thickenings, and the presence of the stomium which acts as a breaking point.

 

Question 42. List out the functions of tapetum.
Answer: The tapetum is the innermost layer of the anther wall, surrounding the developing pollen grains. It has several important functions:

• It provides essential nutrients to the developing microspores (young pollen cells).
• It helps in forming sporopollenin through structures called ubisch bodies. Sporopollenin is a very tough material that forms the outer protective layer of pollen grains, helping them survive harsh conditions.
• Tapetal cells contribute material for Pollenkitt, an oily, sticky layer that often coats pollen surfaces, especially in insect-pollinated plants.
• It contributes exine proteins which are involved in rejection reactions on the stigma, ensuring that only compatible pollen can germinate.

In simple words: The tapetum is a key layer inside the flower's anther that feeds the growing pollen. It helps make the strong outer shell of pollen, adds a sticky coating, and even helps flowers decide which pollen is the right match.

🎯 Exam Tip: When listing tapetum functions, remember its key roles: nourishment, sporopollenin formation, pollenkitt contribution, and exine protein provision for pollen-stigma interaction.

 

Question 43. Write a short note on Pollen kitt.
Answer: Pollenkitt is a special, oily layer that forms on the outside of pollen grains, mainly in plants pollinated by insects. It is produced and contributed by the tapetum, which is a nutritive layer in the anther. Pollenkitt is typically yellow or orange in color because it is made up of carotenoids or flavonoids. This sticky, viscous coating serves several purposes: it helps the pollen grains stick to the bodies of insects, thus attracting pollinators. It also offers protection to the pollen grains from harmful ultraviolet (UV) radiation. This oily layer ensures the pollen is visible and safely transported.
In simple words: Pollenkitt is a colorful, sticky, oily coating on pollen grains, made by the tapetum. It helps pollen stick to insects for pollination and protects the pollen from strong sun.

🎯 Exam Tip: For Pollenkitt, remember its composition (carotenoids/flavonoids), origin (tapetum), and dual function: insect attraction and UV protection.

 

Question 44. Distinguish tenuinucellate and crassinucellate ovules.
Answer: Tenuinucellate and crassinucellate are two types of ovules distinguished by the thickness and development of their nucellus tissue, which is the central part of the ovule where the embryo sac develops.

Tenuinucellate Ovule:

1. The sporogenous cell (the cell that develops into the embryo sac) is located directly beneath the epidermal layer, making it hypodermal.
2. It has only a single layer of nucellar tissue, which is quite thin.
3. Consequently, the nucellus itself is very small.

Crassinucellate Ovule:

1. The sporogenous cell is located deeper within the ovule, meaning it's sub-hypodermal, covered by multiple layers of nucellar tissue.
2. It has many layers of cells forming its nuclear tissue.
3. This results in a fairly large nucellus.

In simple words: Tenuinucellate ovules have a thin central part (nucellus) with just one cell layer, and the cell that makes the embryo sac is right under the skin. Crassinucellate ovules have a thick central part with many cell layers, and the embryo sac cell is deeper inside.

🎯 Exam Tip: When differentiating, focus on the nucellus thickness, the position of the sporogenous cell (hypodermal vs. sub-hypodermal), and the number of nucellar cell layers.

 

Question 45. 'Pollination in Gymnosperms is different from Angiosperms' – Give reasons.
Answer: Pollination in gymnosperms is indeed different from angiosperms, mainly because of the way their ovules are structured and protected.
In gymnosperms (like pine trees), the ovules are "naked" or exposed. This means the pollen grains can be deposited directly onto the ovule itself. Therefore, pollination in gymnosperms is considered "direct" because there is no intervening structure between the pollen and the ovule.
In contrast, angiosperms (flowering plants) have their ovules enclosed within an ovary. For pollination to occur, pollen grains must first land on a receptive structure called the stigma (which is part of the pistil). From the stigma, the pollen tube grows down to reach the ovule inside the ovary. Because the pollen is first deposited on the stigma and then has to grow to reach the ovule, pollination in angiosperms is considered "indirect."
In simple words: Pollination in gymnosperms is direct because their ovules are open, so pollen lands right on them. In flowering plants (angiosperms), it's indirect because pollen first lands on a sticky part called the stigma, and then a tube grows to reach the hidden ovule.

🎯 Exam Tip: The key difference lies in the ovule's protection: exposed in gymnosperms (direct pollination) versus enclosed in an ovary in angiosperms (indirect pollination via stigma).

 

Question 46. Write a short note on Heterostyly.
Answer: Heterostyly is a floral mechanism found in some plants that helps to promote cross-pollination and prevent self-pollination. It involves flowers within the same species having different lengths of stamens (male parts) and styles (female parts). This ensures that pollen from one flower type is ideally positioned to be transferred to the stigma of a different flower type, facilitating genetic mixing.
1. Some plants produce flowers that vary in the length of their stamens and styles. For effective pollination, pollen transfer needs to happen between organs of similar length from different flowers.
a) Distyly (Example: Primula): In these plants, there are two types of flowers.

• "Thrum-eyed" flowers have short styles and long stamens.
• "Pin-eyed" flowers have long styles and short stamens.
• Pollination works best when pollen from the long stamens of a thrum-eyed flower reaches the long stigma of a pin-eyed flower, and vice versa.

In simple words: Heterostyly is a plant strategy where flowers of the same kind have male and female parts of different lengths. This makes it harder for a flower to pollinate itself and easier for pollen to go to a different flower, which helps mix up plant genes.

🎯 Exam Tip: When explaining heterostyly, emphasize that it involves varying stamen and style lengths within a species to promote cross-pollination and give Primula (Distyly) as a classic example.

 

Question 47. Enumerate the characteristic features of Entomophilous flowers.
Answer: Entomophilous flowers are those that are pollinated by insects. These flowers have special features designed to attract insects and ensure successful pollen transfer:

1. Flowers are usually large and showy. If they are small, they are often grouped together in dense clusters (inflorescences) to look like one big flower. For example, flowers in the Asteraceae family.
2. They are brightly colored to attract insects. Sometimes, even nearby parts of the flower, like bracts (modified leaves), become colored to draw attention, as seen in Poinsettia and Bougainvillea.
3. Many entomophilous flowers produce a scent and nectar, which serve as rewards for insect visitors.
4. If a flower does not produce nectar, it might offer pollen as food, or the pollen might be used by insects to build their nests. Pollen and nectar are key rewards that bring insects to visit.
5. Flowers pollinated by flies and beetles often produce a foul odor, which surprisingly attracts these specific types of pollinators.
6. Some flowers have juicy cells that insects can pierce and feed on, also attracting them for pollination.
In simple words: Entomophilous flowers use tricks to attract insects for pollination. They are often big, bright, colorful, scented, or offer sweet nectar or pollen. Some even smell bad to attract flies and beetles.

🎯 Exam Tip: When listing features of insect-pollinated flowers, cover sensory attractants (color, scent, nectar) and structural adaptations (size, clustering) that facilitate insect visits and pollen transfer.

 

Question 48. Discuss the steps involved in Microsporogenesis.
Answer: Microsporogenesis is the process by which haploid microspores (which later develop into pollen grains) are formed from a diploid microspore mother cell through meiosis. Here are the steps:

• The primary sporogenous cells, located within the anther, first undergo mitotic divisions to form more sporogenous tissue.
• These sporogenous tissue cells then function as microspore mother cells.
• Each diploid microspore mother cell then undergoes meiosis, a special type of cell division, to form a tetrad of four haploid microspores.
• These microspores eventually separate and become free within the anther locule (chamber). They then develop into mature pollen grains.
• In some plants, microspores are held together in a structure called a pollinium. A filament-like part, called the retinaculum, attaches the pollinium to a clip-like structure called a corpusculum, forming a "Translator" (Y-shaped) mechanism for insect dispersal.

In simple words: Microsporogenesis is how pollen is made. First, special cells in the flower grow and then divide in a unique way called meiosis. This makes four small, single-chromosome cells called microspores. These microspores then grow into mature pollen grains, ready for spreading.

🎯 Exam Tip: Key steps in microsporogenesis include: sporogenous cells becoming microspore mother cells, meiosis forming a tetrad of haploid microspores, and their subsequent development into pollen grains.

 

Question 49. With a suitable diagram explain the structure of an ovule.
Answer: The ovule, also known as the megasporangium, is a structure found in flowering plants that contains the female reproductive cells. It eventually develops into a seed after fertilization. Here is its structure:

• The ovule (megasporangium) has a stalk called the funiculus and a main body.
• The funiculus is located at the base of the ovule and connects it to the placenta, which provides nutrients.
• The hilum is the specific point where the funiculus joins the main body of the ovule.
• In an inverted ovule, the funiculus is fused with the body of the ovule, forming a ridge called the raphe.
• The central part of the ovule's body is a mass of reserve food tissue called the nucellus.
• The nucellus is protected by one or two layers of integuments (outer coverings).
• The integument completely covers the nucellus except for a small opening at the top called the micropyle.
• An ovule with a single integument is called unitegmic.
• The chalaza is the region at the base of the ovule where the nucellus, integument, and funicle all meet.
• Inside the nucellus, towards the micropylar end, is a sac-like structure called the embryo sac (or female gametophyte), which develops from a functional megaspore.
• The innermost layer of the integument can be a specialized nutritive layer called the integumentary tapetum or endothelium.
• A tenuinucellate ovule has a hypodermal sporogenous cell and a single layer of nucellar tissue.
• A crassinucellate ovule has a sub-hypodermal sporogenous cell and multiple layers of nucellar tissue.
• A group of cells found between the chalaza and the embryo sac is called the hypostase.
• Thick-walled cells located above the micropyle are called the epistase.

In simple words: An ovule is like a small egg inside a plant, which will grow into a seed. It has a stalk (funiculus) that connects it to the plant, and an opening (micropyle). Inside, it has a food-rich part (nucellus) and a special sac (embryo sac) where the baby plant will start to grow.

🎯 Exam Tip: When drawing and explaining the ovule, clearly label the funiculus, hilum, micropyle, integuments, nucellus, embryo sac, and chalaza, and briefly describe each part's function. Ensure the diagram clearly shows these connections and regions.

 

Question 50. Give a concise account on steps involved in the fertilization of an angiosperm plant.
Answer: Fertilization in angiosperms (flowering plants) is a complex process involving several steps to ensure the fusion of male and female gametes:

1. Germination of pollen to form a pollen tube in the stigma:

• Pollen grains land on the receptive stigma of a flower.
• If the pollen is compatible, it absorbs moisture (hydration) and nutrients from the stigma and germinates, forming a pollen tube. Pollen wall proteins are released during this.
• The stigma's fluid and a thin covering (pellicle) on dry stigmas help this process.
• The compatibility or rejection of pollen is determined by a protein reaction between the pollen and the stigma surface.
• The entire contents of the pollen grain move into the growing pollen tube.
• Growth mainly occurs at the tip of the pollen tube, with a vacuole occupying the older part.
• The pollen tube tip is called a 'cap block', which later disappears, and the tube stops growing once it reaches its target.

2. Growth of the pollen tube in the style:

• In hollow styles, glandular canal cells secrete a mucilaginous (sticky) substance. These secretions provide nutrition for the growing pollen tube and control its compatibility with the style.
• In solid styles, the pollen tube grows through the spaces between cells of the transmitting tissue. Semi-solid styles are a mix between solid and open types.

3. Entry of the pollen tube into the ovule:

• Propogamy: The pollen tube enters the ovule through the micropyle (the small opening).
• Chalazogamy: The pollen tube enters through the chalaza (the base of the ovule).
• Monogamy: The pollen tube enters through the integument (outer covering).

4. Entry of the pollen tube into the embryo sac:

• The pollen tube usually enters the embryo sac at its micropylar end, guided by special cells called obturators.
• It then enters one of the synergids, which are cells next to the egg cell.

5. Double fertilization and Triple fusion:

• In angiosperms, both male gametes are involved in fertilization.
• One male gamete fuses with the egg nucleus (syngamy) to form the zygote.
• The second male gamete moves to the central cell and fuses with the polar nuclei (or secondary nucleus). This forms the primary endosperm nucleus (PEN). Since this involves the fusion of three nuclei, it is called triple fusion.

In simple words: Fertilization in flowering plants starts when pollen lands on the stigma and grows a tube down to the ovule. This tube carries male cells to the egg. Inside the ovule, one male cell joins with the egg to make the baby plant (zygote), and another male cell joins with central cells to make food for the baby plant (endosperm). This two-part joining is called double fertilization.

🎯 Exam Tip: Structure your answer by breaking down fertilization into key stages: pollen germination, pollen tube growth through the style, entry into the ovule, entry into the embryo sac, and finally, the double fertilization and triple fusion events.

 

Question 51. What is endosperm. Explain the types. (OR) Write the three fusion of Antispermous plant fertilization.
Answer: The endosperm is a nutritive tissue that develops in the seeds of flowering plants (angiosperms) after fertilization. Its primary function is to provide food and support for the developing embryo. The zygote divides only after the endosperm has formed, ensuring the embryo has a food supply. The Primary Endosperm Nucleus (PEN) is crucial in regulating this structure. There are three main types of endosperm, classified by their mode of development:

a) Nuclear Endosperm (Example: Arachis - groundnut):

• In this type, the Primary Endosperm Nucleus (PEN) undergoes many mitotic divisions.
• However, these divisions are not immediately followed by cell wall formation.
• This results in a "free nuclear condition" where many nuclei float within a common cytoplasm. Cell walls form later, if at all.

b) Cellular Endosperm (Example: Helianthus - sunflower):

• Here, the Primary Endosperm Nucleus (PEN) divides, and each nuclear division is immediately followed by the formation of a cell wall.
• This leads to the formation of distinct cells right from the start, making the endosperm fully cellular.

c) Helobial Endosperm (Example: Vallisneria):

• This type is an intermediate between nuclear and cellular endosperm.
• The Primary Endosperm Nucleus (PEN) moves towards the base of the embryo sac and then divides into two nuclei.
• A cell wall forms after this first division, dividing the embryo sac into a large micropylar chamber (towards the ovule opening) and a small chalazal chamber (at the base).
• Nuclei in the micropylar chamber divide freely without immediate cell wall formation, while the nucleus in the chalazal chamber often does not divide or divides minimally.

In simple words: Endosperm is food stored in a seed to feed the growing baby plant. There are three types: nuclear, where many nuclei float freely before cell walls form; cellular, where cells form right after each division; and helobial, which is a mix of both, forming two chambers after the first division.

🎯 Exam Tip: When explaining endosperm types, remember to describe the key features of each (free nuclear divisions, immediate cell wall formation, or a combination) and provide a relevant example for each type.

 

Question 52. Differentiate the structure of Dicot and Monocot seed.
Answer: Dicot (dicotyledonous) and monocot (monocotyledonous) seeds differ significantly in their internal and external structures:

Structure of a Dicot Seed (e.g., Pea, Bean, Castor):

1. Dicot seeds typically have two cotyledons, which are leaf-like structures that store food for the embryo.
2. They are usually two-seeded or have two distinct halves.
3. The seed coat has an outer layer called the testa and an inner layer called the tegmen.
4. In seeds like peas, the cotyledons store the food. In castor seeds, the endosperm stores reserve food.
5. Structures like the coleoptile (sheath covering the plumule) and coleorhiza (sheath covering the radicle) are absent.

Structure of a Monocot Seed (e.g., Paddy, Maize):

1. Monocot seeds have only one cotyledon, often called the scutellum.
2. They are typically one-seeded.
3. The seed is enclosed by a husk, and the thin, brown, membranous seed coat is tightly attached to the grain.
4. The scutellum (cotyledon) supplies food from the endosperm to the embryo through a special epithelial layer.
5. Coleoptile and coleorhiza are present, protecting the embryonic shoot and root respectively.

In simple words: Dicot seeds have two main food-storing leaves (cotyledons), like a bean, and no special covers for the shoot or root. Monocot seeds have only one cotyledon (like a grain of rice), and they have protective covers called coleoptile and coleorhiza for the baby shoot and root.

🎯 Exam Tip: When differentiating dicot and monocot seeds, the most important points are the number of cotyledons (two vs. one) and the presence/absence of protective sheaths (coleoptile/coleorhiza).

12th Bio Botany Guide Asexual and Sexual Reproduction in Plants in Animals Additional Important Questions and Answers

I. Choose the correct answer

 

Question 1. Match the following

(a) A-1, B-2, C-4, D-3
(b) A-1, B-2, C-3, D-4
(c) A-4, B-3, C-2, D-1
(d) A-2, B-1, C-4, D-3
Answer: (a) A-1, B-2, C-4, D-3
In simple words: This question tests your knowledge of who discovered what in plant embryology. Matching each scientist to their specific contribution helps to identify the correct answer.

🎯 Exam Tip: When matching, eliminate the obvious pairs first. If you know one pair for sure, check if it appears in multiple options and narrow down from there.

 

Question 2. Find the matching pair
(a) Rhizome - Zingiber
(b) Corm - Solanum
(c) Tuber - Lilium
(d) Stolon - Zingiber
Answer: (a) Rhizome - Zingiber
In simple words: A rhizome is a type of underground stem that grows horizontally, and ginger (Zingiber) is a perfect example of a plant with a rhizome. The other options are incorrect pairings of plant parts and examples.

🎯 Exam Tip: Remember key examples for each type of modified plant stem (rhizome, corm, tuber, stolon, bulb) as these are frequently tested.

 

Question 3. Find the mismatching pair
(a) Runner - Centella
(b) Sucker - Chrysanthemum
(c) Stolon - Fragaria
(d) Offset - Bryophyllum
Answer: (d) Offset - Bryophyllum
In simple words: An offset is a short, thick runner-like stem that grows from the main plant, commonly seen in aquatic plants like Pistia or Eichhornia. Bryophyllum reproduces using buds on its leaf margins, not offsets, making this pair mismatched.

🎯 Exam Tip: Understand the specific type of vegetative propagation each plant example demonstrates. Bryophyllum is famous for its epiphyllous buds.

 

Question 4. Epiphyllous buds are in
(a) Chrysanthemum
(b) Agave
(c) Curcuma
(d) Scilla
Answer: (d) Scilla
In simple words: Epiphyllous buds are special buds that grow on the edges or surface of a leaf. Scilla, like Bryophyllum, is known for having these buds on its leaves, which can grow into new plants.

🎯 Exam Tip: Epiphyllous buds are a distinct feature of vegetative propagation from leaves; recall plants that exhibit this unusual trait.

 

Question 5. Eyes of potato are referred to
(a) adventitious roots
(b) axillary buds
(c) terminal buds
(d) intercalary buds
Answer: (b) axillary buds
In simple words: The "eyes" on a potato are actually dormant buds located in the axils of scale leaves. These buds can sprout and grow into new potato plants, making the potato a type of modified stem for vegetative reproduction.

🎯 Exam Tip: Remember that a potato is a tuber (modified stem), and its "eyes" are nodes with axillary buds, not roots or other types of buds.

 

Question 6. The T-shaped incision is made in grafting.
(a) Bud
(b) Approach
(c) Tongue
(d) Crown
Answer: (a) Bud
In simple words: In bud grafting, a T-shaped cut is made in the bark of the stock plant. A bud, along with a small piece of bark, is then inserted into this T-cut to grow a new plant.

🎯 Exam Tip: Familiarize yourself with the specific cuts and methods used in different grafting techniques, as these details are important.

 

Question 7. Plants propagated economically by vegetative propagation
(a) Solanum tuberosum
(b) Ixora
(c) Jasminum
(d) Chrysanthemum
Answer: (a) Solanum tuberosum
In simple words: Solanum tuberosum, which is potato, is often grown using vegetative propagation (planting tubers) for farming. This method is economically important for ensuring consistent crop quality and yield.

🎯 Exam Tip: Think of common food crops that are grown from parts of the plant rather than seeds to easily recall examples of economic vegetative propagation.

 

Question 8. Steward produced................plant from phloem
(a) Beetroot
(b) Carrot
(c) Solanum
(d) Radish
Answer: (b) Carrot
In simple words: F.C. Steward was a scientist who showed that a whole carrot plant could be grown from just a single cell taken from its phloem tissue. This experiment was very important in showing the concept of totipotency.

🎯 Exam Tip: Recall the classic tissue culture experiments, particularly Steward's work with carrot, as it's a foundational example in plant biotechnology.

 

Question 9. Arrange from the periphery to centre in another wall.
(a) Endothecium, Middle layer, tapetum
(b) Tapetum, middle layer, Endothecium
(c) Endothecium, tapetum, middle layer
(d) Middle layer, endothecium, tapetum
Answer: (a) Endothecium, Middle layer, tapetum
In simple words: The anther wall has several layers. Starting from the outside, it has the epidermis, then the endothecium, followed by the middle layers, and finally the tapetum, which is the innermost layer. This order is from the outside moving inwards towards the center.

🎯 Exam Tip: Visualize the cross-section of an anther and the distinct layers of its wall. Knowing the order (Epidermis, Endothecium, Middle layers, Tapetum) is crucial.

 

Question 10. Microspores are held together by pollinium in
(a) Hibiscus
(b) Calotropis
(c) Ixora
(d) Datura
Answer: (b) Calotropis
In simple words: In plants like Calotropis, all the microspores within a microsporangium stick together in a single mass called a pollinium. This special structure helps with pollen transfer.

🎯 Exam Tip: Recognise that pollinium formation is a unique adaptation for pollen dispersal, often associated with specific plant families like Asclepiadaceae (which includes Calotropis).

 

Question 11. ...... cells are hygroscopic in anther wall.
(a) Epidermis
(b) Endothecium
(c) Middle layer
(d) tapetum
Answer: (b) Endothecium
In simple words: The cells of the endothecium layer in the anther wall are hygroscopic, meaning they can absorb moisture from the air. This property helps the anther to split open and release pollen when it is mature.

🎯 Exam Tip: Link the hygroscopic nature of the endothecium to its role in the dehiscence (opening) of the anther, which is essential for pollen release.

 

Question 12. Find the wrong statement
(a) Invasive tapetum is periplasmodial.
(b) Amoeboid tapetum is associated with male sterility
(c) Middle layer is ephemeral.
(d) Epithelium is hygroscopic
Answer: (d) Epithelium is hygroscopic
In simple words: The epithelium is the outer protective layer of the anther, and its cells are not hygroscopic. It is the endothecium layer that has hygroscopic cells, which help in the anther opening.

🎯 Exam Tip: Differentiate between the functions and characteristics of each anther wall layer (epidermis, endothecium, middle layers, tapetum) to avoid confusion.

 

Question 13. Find the correct statement
(a) Carrot grass causes allergy
(b) Bee pollen is an artificial substance.
(c) Palynology is the study of honey pollen.
(d) Mellitopalynology is the study of pollen grain.
Answer: (a) Carrot grass causes allergy
In simple words: Carrot grass (Parthenium hysterophorus) is a known cause of pollen allergies in humans. The other statements are incorrect as bee pollen is natural, palynology is the study of all pollen, and mellitopalynology is specifically the study of pollen found in honey.

🎯 Exam Tip: Be aware of the common causes of pollen allergies and the specific terms related to pollen study (palynology) and honey pollen study (mellitopalynology).

 

Question 14. Not a shape of pollen grain
(a) Globose
(b) Ellipsoid
(c) crescent-shaped
(d) Cubical
Answer: (d) Cubical
In simple words: Pollen grains come in many shapes, such as round (globose), oval (ellipsoid), crescent-shaped, or even kidney-shaped. However, they are not cubical.

🎯 Exam Tip: Recall the diverse morphologies of pollen grains and identify shapes that are not typically observed in nature.

 

Question 15. ............ protects pollen grain from UV
(a) Sporopollenin
(b) pollenkitt
(c) Exine
(d) callose.
Answer: (a) Sporopollenin
In simple words: Sporopollenin is a tough, durable substance found in the outer wall of pollen grains, called the exine. It acts like a strong shield, protecting the pollen from harmful things like UV radiation, strong acids, and biological breakdown.

🎯 Exam Tip: Remember sporopollenin as one of the most resistant organic materials known, crucial for pollen survival and fossilization.

 

Question 16. Not in exine of pollen grain
(a) Cellulose
(b) Sporopollenin
(c) Pollenkitt
(d) Callose
Answer: (d) Callose
In simple words: The exine, or outer layer of the pollen grain, is mainly made of sporopollenin and can also have pollenkitt on its surface. Cellulose and callose are found in other parts of the plant, but not typically as a component of the mature pollen exine.

🎯 Exam Tip: Distinguish between the chemical composition of the exine (sporopollenin, pollenkitt) and intine (cellulose, pectin) and callose (wound response/pollen tube plug).

 

Question 17. .................. % of angiosperm pollen is liberated in 2 cell stage
(a) 50
(b) 60
(c) 40
(d) 30
Answer: (b) 60
In simple words: In most flowering plants, about 60% of pollen grains are released when they have two cells: a large vegetative cell and a smaller generative cell. The generative cell divides later to form two male gametes.

🎯 Exam Tip: Remember the typical stages of pollen liberation (2-celled or 3-celled) and the approximate percentage for each.

 

Question 18. Which one of the following is a dioecious plant?
(a) Coconut
(b) Bitter gourd
(c) Pea plant
(d) Date palm
Answer: (d) Date palm
In simple words: A dioecious plant has male and female flowers on separate plants. Date palm is an example where individual plants are either purely male or purely female.

🎯 Exam Tip: Understand the difference between monoecious (male and female flowers on the same plant) and dioecious (male and female flowers on different plants).

 

Question 19. Match the following

(a) A-4, B-3, C-2, D-1
(b) A-1, B-2, C-3, D-4
(c) A-4, B-2, C-3, D-1
(d) A-2, B-1, C-4, D-3
Answer: (a) A-4, B-3, C-2, D-1
In simple words: This question tests your knowledge of different ovule types and the plant families where they are found. Orthotropous ovules are straight and seen in Piperaceae, while anatropous ovules are inverted and common in dicots and monocots. Hemianatropous ovules are at a right angle, typical of Primulaceae, and campylotropous ovules are curved, found in Leguminosae.

🎯 Exam Tip: Memorize the characteristics and common examples for each type of ovule orientation, as these are fundamental to understanding plant reproduction.

 

Question 20. Horseshoe shaped nucellus is in ............... ovule.
(a) Circinotropous
(b) Amphitropous
(c) Anatropous
(d) Hemianatropous
Answer: (b) Amphitropous
In simple words: In an amphitropous ovule, the nucellus and embryo sac are curved, giving them a horseshoe shape. This curvature brings the micropyle and chalaza closer together.

🎯 Exam Tip: Associate the horseshoe shape with amphitropous ovules and understand how this curvature impacts the position of the funicle, micropyle, and chalaza.

 

Question 21. Find the mismatching pair
(a) Tetrasporic - Peperomia
(b) Bisporic - Allium
(c) Monosporic - Polygonum
(d) Trisporic - Cactaceae
Answer: (d) Trisporic - Cactaceae
In simple words: The classification of embryo sac development refers to how many megaspores are involved. Cactaceae typically exhibit bisporic development, not trisporic, making this the mismatching pair.

🎯 Exam Tip: Learn the different types of embryo sac development (monosporic, bisporic, tetrasporic) and their characteristic examples.

 

Question 22. Homogamy is in ...............
(a) Mirabilis
(b) Commelina
(c) Viola
(d) Oxalis.
Answer: (a) Mirabilis
In simple words: Homogamy is when the anthers (male parts) and stigma (female parts) of a flower mature at the same time. Mirabilis (four o'clock flower) is known for this trait.

🎯 Exam Tip: Homogamy ensures self-pollination if other mechanisms don't prevent it; identify common examples where this occurs naturally.

 

Question 23. Protogyny is in ................
(a) Aristolochia
(b) Helianthus
(c) Viola
(d) Oxalis.
Answer: (a) Aristolochia
In simple words: Protogyny is a condition where the female reproductive parts (stigma) of a flower mature before the male reproductive parts (anthers). Aristolochia (Dutchman's pipe) is an example of a plant that exhibits protogyny.

🎯 Exam Tip: Protogyny is a common strategy to promote cross-pollination by preventing self-pollination within the same flower. Understand its opposite, protandry.

 

Question 24. Distyly is in ................
(a) Primula
(b) Lythrum
(c) Abutilon
(d) Hibiscus
Answer: (a) Primula
In simple words: Distyly is a type of heterostyly where flowers have two different forms based on the length of their stamens and styles. Primula is a classic example of a distylous plant.

🎯 Exam Tip: Distyly, along with Tristyly, are mechanisms to ensure cross-pollination. Remember Primula as the key example for distyly.

 

Question 25. Find the mismatching following
(a) Passiflora - self sterility
(b) Gloriosa - Herkogamy
(c) Sugarcane - Anemophily
(d) Urtica - Hydrophily
Answer: (d) Urtica - Hydrophily
In simple words: Urtica (nettle) is known for wind pollination (anemophily), not water pollination (hydrophily). The other pairs correctly match the plant to its reproductive characteristic.

🎯 Exam Tip: Accurately connect plants with their specific pollination mechanisms (e.g., wind, water, insect, bird, bat) and self-incompatibility traits.

 

Question 26. Find the matching pair
(a) Epihydrophily - Elodea.
(b) Ornithaphily - Lemna
(c) Entomophily - Vallisneria
(d) Hydrophily - Kigelia.
Answer: (a) Epihydrophily - Elodea.
In simple words: Epihydrophily is a type of water pollination where pollen floats on the water surface. Elodea is a plant that uses this method. The other options are mismatched: Ornithophily is bird pollination (not Lemna), Entomophily is insect pollination (Vallisneria is water-pollinated), and Kigelia is bat-pollinated.

🎯 Exam Tip: Distinguish between epihydrophily (pollen on water surface) and hypohydrophily (pollen under water surface), and know examples for each.

 

Question 27. Find the odd one. Not dealing with entry of pollen tube
(a) Herkogamy
(b) Porogamy
(c) Mesogamy
(d) chalazogamy
Answer: (a) Herkogamy
In simple words: Porogamy, mesogamy, and chalazogamy are all different ways a pollen tube can enter the ovule during fertilization. Herkogamy, however, is a physical barrier within the flower that prevents self-pollination, not a method of pollen tube entry.

🎯 Exam Tip: Understand the three main pathways of pollen tube entry into the ovule (porogamy, chalazogamy, mesogamy) and differentiate them from mechanisms that prevent self-pollination like herkogamy.

 

Question 28. Not a post-fertilization change
(a) Endosperm
(b) Embryo development
(c) Seed formation
(d) Triple fusion
Answer: (d) Triple fusion
In simple words: Triple fusion is an event that happens during fertilization, where one male gamete fuses with the central cell to form the primary endosperm nucleus. The development of endosperm, embryo, and seeds are all processes that occur *after* fertilization has completed.

🎯 Exam Tip: Clearly separate pre-fertilization events (like pollen formation), fertilization events (like syngamy and triple fusion), and post-fertilization events (like endosperm and embryo development, fruit and seed formation).

 

Question 29. Matching

(a) A-1, B-4, C-3, D-2
(b) A-1, B-2, C-3, D-4
(c) A-4, B-3, C-2, D-1
(d) A-2, B-1, C-4, D-3
Answer: (a) A-1, B-4, C-3, D-2
In simple words: This question matches plant parts or features to specific examples or definitions. Apple is a false fruit where the receptacle becomes edible. Jackfruit develops from a fleshy perianth. The juicy flower stalk is a feature of Anacardium (cashew). Perisperm is the remnant of the nucellus, often found in seeds like beetroot.

🎯 Exam Tip: Connect the botanical definitions of fruit types (e.g., false fruit, multiple fruit) and seed structures (e.g., perisperm) with specific plant examples.

 

Question 30. Matching the following

(a) A-4, B-3, C-2, D-1
(b) A-1, B-2, C-4, D-3
(c) A-2, B-1, C-4, D-3
(d) A-3, B-2, C-1, D-4
Answer: (a) A-4, B-3, C-2, D-1
In simple words: After fertilization, the ovary develops into a fruit, the ovule becomes a seed, the secondary nucleus forms the endosperm, and the egg cell develops into a zygote. This shows the changes that happen after the fusion of gametes.

🎯 Exam Tip: Understand the fate of different floral parts after fertilization (e.g., ovary to fruit, ovule to seed, egg to zygote, central cell to endosperm).

 

Question 31. Which one of the following statements is not true regarding sporopollenin?
(a) Sporopollenin is contributed by both pollen cytoplasm and tapetum.
(b) It helps the pollen to withstand strong acid.
(c) Sporopollenin is derived from phycobilins
(d) It helps pollen during long period perservation in fossil deposits.
Answer: (a) Sporopollenin is contributed by both pollen cytoplasm and tapetum.
In simple words: Sporopollenin is primarily produced by the tapetum (nutritive layer of the anther), not directly by the pollen cytoplasm. It is known for its extreme resistance to chemicals and decay, which helps in fossil preservation and protection from harsh conditions.

🎯 Exam Tip: Know the origin and unique properties of sporopollenin, especially its role in pollen protection and fossilization, and that its synthesis is from the tapetum.

 

Question 32. True (or) False
1) Beetles show Palaenophily
2) Bees show Cantharophily
3) Snails show Malacophily
4) Ants show Myrmecophily
(a) 1,2,3 true 4 is false
(b) 1,2 are true, 3,4 are false
(c) 1,2,3 are true, 4 true
(d) 1 is true 2,3,4 are false
Answer: (a) 1,2, 3 true 4 is false
In simple words: This question checks your understanding of different pollination types. Beetles are involved in cantharophily (not palaenophily, which is more general for primitive flowers), bees are involved in melittophily (not cantharophily which is beetle pollination), snails show malacophily, and ants show myrmecophily. So, statement 1, 2, 3 are considered true in some contexts (though cantharophily is specifically beetle pollination and melittophily for bees), but statement 4 is definitively true. The provided answer seems to consider 1,2,3 true and 4 false, implying a different set of definitions or a specific interpretation where Palaenophily, Cantharophily and Malacophily are accepted and Myrmecophily is not. For this question, only statement 4 is reliably true as written in standard texts for ant pollination. Given the options, there might be a subtle distinction being made, but sticking to general understanding, ants indeed show myrmecophily. However, following the given answer (a), we assume 1,2,3 true, and 4 false for this context. For a typical exam, Myrmecophily (ant pollination) is indeed a known term. Therefore, the mismatch is likely in statement 4 being *false* while it is generally considered true.

🎯 Exam Tip: Be precise with the terminology for animal pollination (e.g., entomophily for insects, melittophily for bees, cantharophily for beetles, malacophily for snails, myrmecophily for ants, chiropterophily for bats) and their correct examples.

 

Question 33. Find the mismatching pair
(a) Trap mechanism - Aristolochia.
(b) Pit fall mechanism - Arum.
(c) Clip mechanism - Asclepiadaceae
(d) Piston mechanism - Salvia
Answer: (d) Piston mechanism - Salvia
In simple words: Salvia uses a lever mechanism for pollination, not a piston mechanism. The other pairs correctly link the plant with its specific pollination mechanism.

🎯 Exam Tip: Focus on understanding the unique adaptations and mechanisms plants use for pollination, especially for less common types like trap, pitfall, clip, and lever mechanisms.

 

Question 34. Find the mismatching pair
(a) Obligate mutualism - Tridax
(b) Pollen robber - Amurphophallus.
(c) Pseudo copulation - Ophyrus.
(d) Fig pollination - Wash.
Answer: (a) Obligate mutualism - Tridax
In simple words: Obligate mutualism refers to a relationship where two species depend entirely on each other for survival, like fig and fig wasp. Tridax, a common weed, does not exhibit this type of specific mutualism. The other pairs correctly describe examples of pollen robbing, pseudocopulation, and fig pollination.

🎯 Exam Tip: Understand different ecological interactions related to pollination, such as mutualism (obligate and facultative), commensalism, and exploitation (pollen robbing, mimicry).

 

Question 35. Fritillaria imperialis shows vegetative propagation by
(a) Bulb
(b) Runner
(c) Bulbils
(d) Sucker
Answer: (c) Bulbils
In simple words: Fritillaria imperialis, also known as crown imperial, reproduces vegetatively through bulbils. Bulbils are small, fleshy buds that form in the leaf axils or flower clusters and can detach to grow into new plants.

🎯 Exam Tip: Differentiate between various vegetative propagules like bulbs, runners, bulbils, suckers, rhizomes, etc., and associate them with specific plant examples.

 

Question 36. Generative apospory is in
(a) Aerva
(b) Ulmus
(c) Balanophova
(d) Allium
Answer: (a) Aerva
In simple words: Generative apospory is a type of apomixis where the embryo sac develops directly from an unreduced archesporial cell without meiosis. Aerva is an example of a plant that displays this form of reproduction.

🎯 Exam Tip: Understand the different types of apomixis (e.g., apospory, diplospory) and their mechanisms, as well as specific plant examples for each.

 

Question 37. Terror of Bengal is
(a) Eichhornia
(b) Centella
(c) Lilium
(d) Murraya
Answer: (a) Eichhornia
In simple words: Eichhornia crassipes, commonly known as water hyacinth, is referred to as the "Terror of Bengal" because of its extremely rapid vegetative reproduction, which allows it to quickly cover water bodies, suffocating aquatic life and disrupting ecosystems.

🎯 Exam Tip: Remember the common names and ecological impacts of invasive species like water hyacinth, particularly in the context of their rapid reproductive strategies.

 

Question 39. Jasminum shows-..................
(a) Bud grafting
(b) Approach grafting
(c) Crown grafting
(d) None
Answer: (d) None
In simple words: Jasminum usually grows new plants by a method called layering, not by the grafting types mentioned in the options. This is because layering techniques promote root development on the stem while it's still attached to the parent plant, making it suitable for plants with flexible branches.

🎯 Exam Tip: When answering questions about plant propagation, remember that different plants are suited for different methods based on their growth characteristics.

 

Question 40. Endangered plants can be produced by
(a) Layering
(b) Grafting
(c) Micropropagation
(d) Cutting
Answer: (c) Micropropagation
In simple words: Micropropagation is a special way to grow many new plants from a small piece of a parent plant. This method allows for the rapid and large-scale multiplication of rare and endangered plant species from very small tissue samples, helping to save them.

🎯 Exam Tip: Remember that micropropagation is crucial for conservation efforts because it can quickly produce many genetically identical plants without needing seeds.

 

Question 41. Disease free plants can be produced by
(a) Meristem, culture
(b) Grafting
(c) Cutting
(d) Layering
Answer: (a) Meristem, culture
In simple words: We can grow plants without diseases by growing cells from their meristem, which is a special part of the plant that is usually virus-free. This technique is very important for agriculture to ensure healthy crops, especially for plants easily affected by diseases.

🎯 Exam Tip: Meristem culture is preferred for disease-free plant production because the meristematic tissue is typically free of pathogens, making it ideal for propagation.

 

Question 42. Which one of the following is not an advantage of micro propagation?
(a) Plants produced are genetically identical
(b) Endangered plants can be propagated
(c) Sometimes undesirable genetical changes occur.
(d) Disease free plants can be produced.
Answer: (c) Sometimes undesirable genetical changes occur.
In simple words: One thing that is NOT good about micropropagation is that sometimes the new plants can have unexpected changes in their genes. Although rare, these genetic changes highlight the need for careful monitoring in large-scale micropropagation projects.

🎯 Exam Tip: While micropropagation offers many benefits, always consider its potential drawbacks, such as the possibility of somaclonal variations (undesirable genetic changes).

 

Question 43. ......................... has underground and aerial flowers
(a) Scrophularia
(b) Catharanthus
(c) Commelina
(d) Clerodendron
Answer: (c) Commelina
In simple words: Commelina is a plant that grows flowers both above the ground and hidden underground. This dual flowering strategy helps ensure seed production even if aerial pollination fails, making it a very adaptable plant.

🎯 Exam Tip: Knowing examples of plants with unique reproductive strategies, like Commelina's cleistogamy and chasmogamy, helps illustrate adaptability in nature.

 

Question 44. Juicy cells are in the ..................... flowers
(a) Ornithophilous
(b) Hydrophilous
(c) Entomophilous
(d) Malacophilous
Answer: (c) Entomophilous
In simple words: Flowers that use insects for pollination (Entomophilous) often have juicy parts to attract the insects. The sweet and juicy parts act as a reward, encouraging insects to visit the flower and help in pollination.

🎯 Exam Tip: For pollination by insects, flowers typically display bright colors, produce nectar, or have juicy tissues as rewards to attract pollinators.

 

Question 45. The central mass of parenchyma in ovule is
(a) Nucellus
(b) Chalaza
(c) Endothelium
(d) Embryosac.
Answer: (a) Nucellus
In simple words: The middle part of the ovule, which is made of soft tissue and stores food, is called the nucellus. This nourishing tissue is crucial for the early growth and development of the new plant embryo.

🎯 Exam Tip: Remember that the nucellus provides essential nutrients to the developing embryo sac, acting as a supportive tissue within the ovule.

 

Question 46. From the following which one is the column of sterile tissue surrounded by the anther lobe.
(a) Periplasodium
(b) pollen chamber
(c) connective tissue
(d) tapetum
Answer: (c) connective tissue
In simple words: The part inside the anther that connects the two halves and does not make pollen is called the connective tissue. This tissue provides structural support to the anther, ensuring the pollen sacs are held correctly.

🎯 Exam Tip: Understand the role of each part of the anther, distinguishing between fertile (pollen-producing) and sterile (supportive) tissues like the connective tissue.

 

Question 47. Oxalis shows-................................
(a) Cleistogamy
(b) Homogamy
(c) Incomplete dichogamy
(d) Geitonogamy
Answer: (a) Cleistogamy
In simple words: Oxalis plants have a special way of reproducing called cleistogamy, where their flowers stay closed and pollinate themselves. This ensures seed production even in the absence of pollinators or unfavorable environmental conditions.

🎯 Exam Tip: Cleistogamy guarantees seed set but leads to less genetic variation, an important trade-off in plant reproduction.

 

Question 48. Brightly coloured bracts attract insects in..................
(a) Poinsettia
(b) Bougainvillea
(c) Lemna
(d) Both a,b
Answer: (d) Both a,b
In simple words: Plants like Poinsettia and Bougainvillea have bright colored leaves called bracts that attract insects to help them pollinate. These bright bracts act as visual signals, guiding pollinators to the actual, often smaller, flowers.

🎯 Exam Tip: Remember that not all showy floral parts are petals; bracts can also be modified to attract pollinators effectively.

 

Question 49. In a male gametophyte, the chromosomal number of generative nucleus is (A)
(a) (A)-(n);(B)-(2n)
(b) (A)-(2n);(B)-(n)
(c) (A)-(2n);(B)-(2n)
(d) (A)-(n);(B)-(n)
Answer: (b) (A)-(2n);(B)-(n)
In simple words: For the male gametophyte, the choice (b) which states (A)-(2n) and (B)-(n) is given as correct. Understanding chromosome numbers is key in genetics, as it dictates how traits are passed from one generation to the next in sexually reproducing organisms.

🎯 Exam Tip: Pay close attention to the specific context of chromosome numbers in questions, as they can sometimes refer to different stages of development.

 

Question 50. Endosperm is formed from-.....................
(a) Ovary
(b) Ovule
(c) egg
(d) Secondary nucleus
Answer: (d) Secondary nucleus
In simple words: The endosperm, which feeds the plant embryo, is made when a male reproductive cell joins with the secondary nucleus. This unique triple fusion creates a nutritive tissue specifically designed to feed the developing plant embryo.

🎯 Exam Tip: Recall that endosperm formation involves triple fusion, where a male gamete fuses with the secondary nucleus, producing a triploid (3n) tissue.

 

Question 51. First cell of Male gametophyte in angio.............
(a) Primary endosperm
(b) Microspore
(c) Megaspore
(d) Nucleus
Answer: (b) Microspore
In simple words: The first cell that grows into the male part of a plant's reproductive system is called a microspore. This tiny microspore holds all the genetic information needed to produce the male reproductive cells for fertilization.

🎯 Exam Tip: Differentiate clearly between microspores (leading to male gametophytes) and megaspores (leading to female gametophytes).

 

Question 52. Malus shows-................................ cutting
(a) Root
(b) stem
(c) leaf
(d) Flower
Answer: (a) Root
In simple words: Apple trees (Malus) can grow new plants from pieces of their roots, which is a type of cutting. This method of vegetative propagation allows for the growth of new plants that are genetically identical to the parent plant.

🎯 Exam Tip: Root cuttings are an effective vegetative propagation method for many plants, including Malus, producing clones of the parent plant.

 

Question 53. Polygonaceae has-.......................type of ovule
(a) Orthotropous
(b) Anatropous
(c) Hemianatropous
(d) Campylotropous.
Answer: (a) Orthotropous
In simple words: Plants from the Polygonaceae family have ovules that are straight, where all the parts line up in a single line. This straight orientation is considered the simplest and most primitive type of ovule structure among flowering plants.

🎯 Exam Tip: Familiarize yourself with the different types of ovule orientations (orthotropous, anatropous, etc.) and their defining characteristics.

 

Question 54. Not an animal pollinater
(a) Lemur
(b) Gecko Lizard
(c) Garden lizard
(d) All of the options
Answer: (d) All of the options
In simple words: Lemurs, gecko lizards, and garden lizards can all help plants pollinate. Many animals, not just insects, play a vital role in transferring pollen, showcasing the diverse ways plants ensure their reproduction.

🎯 Exam Tip: Expand your understanding of pollinators beyond insects; many mammals, birds, and reptiles contribute to plant reproduction.

 

Question 55. This shape is not seen in Tridax embryo
(a) Globular
(b) Heart
(c) torpedo shape
(d) Cuboidal
Answer: (d) Cuboidal
In simple words: Tridax plant embryos grow through round, heart-like, and torpedo-like shapes, but they don't form a cube shape. These distinct shapes represent key phases in the embryo's growth, leading to the formation of a complete seedling.

🎯 Exam Tip: Remember the typical stages of dicot embryo development: globular, heart-shaped, and torpedo-shaped, as these are common identifiers.

 

Question 56. Kigelia africana shows
(a) Cheiropterophily
(b) Malacophily
(c) Entomophily
(d) Zoophily
Answer: (a) Cheiropterophily
In simple words: The Kigelia africana tree uses bats for pollination, which is a process called cheiropterophily. The tree's large, dark red flowers open at night and produce a musky scent and nectar, specifically adapted to attract nocturnal bats.

🎯 Exam Tip: Cheiropterophily is a specific type of zoophily (animal pollination) where bats are the primary pollinators, often seen in plants with nocturnal flowering patterns.

 

Question 28. Redraw the diagram and lable the parts.
Answer: The diagram shows a 2-celled proembryo with a terminal cell and a basal cell.
In simple words: The diagram shows a tiny plant embryo with two main cells: one at the top (terminal cell) and one at the bottom (basal cell). This early stage is called a 2-celled proembryo.

🎯 Exam Tip: When drawing biological diagrams, always ensure clear labels and accurate representation of the structures, as they are crucial for understanding the concept.

 

Question 29. What is cap block?
Answer: A cap block is the clear, rounded tip of a pollen tube. You can see it clearly under a microscope. This specialized tip helps the pollen tube push its way through the plant's tissues. When this cap block disappears, the pollen tube stops growing.
In simple words: It is the clear, rounded end of a pollen tube. When it goes away, the tube stops growing.

🎯 Exam Tip: Define cap block and explain its role in pollen tube growth and eventual cessation of growth.

 

Question 30. What is the significance of obtruator?
Answer: An obturator is important because it guides the pollen tube. It directs the pollen tube through the ovary towards the tiny opening of the ovule called the micropyle. This guidance ensures that fertilization happens correctly by leading the pollen to its target.
In simple words: The obturator guides the pollen tube to the right spot in the ovule for fertilization.

🎯 Exam Tip: Explain the function of the obturator in directing the pollen tube to the micropyle for successful fertilization.

 

Question 31. Suggest the events after fertilization?
Answer: After fertilization, several key changes happen in a plant. First, the endosperm and embryo start to develop inside the ovule. After this, the ovule turns into a seed, and the ovary grows into a fruit. These are called post-fertilization changes. These changes are vital to protect the new embryo and help the plant spread its seeds.
In simple words: After fertilization, the embryo and endosperm grow, then the ovule becomes a seed, and the ovary becomes a fruit.

🎯 Exam Tip: List the main outcomes of fertilization, such as embryo and endosperm development, and the formation of seeds and fruits.

 

Question 32. What is Suspensor?
Answer: A suspensor forms during embryo development. It is made from the basal cell which divides several times to create a structure with six to ten cells. The main job of the suspensor is to push the growing embryo deep into the endosperm, which provides food. This positioning allows the embryo to access nutrients efficiently for its growth.
In simple words: The suspensor is a cell structure that pushes the embryo deep into the food-rich endosperm.

🎯 Exam Tip: Describe how the suspensor forms and its crucial role in embedding the embryo within the endosperm.

 

Question 33. What is Callus?
Answer: A callus is a group of plant cells that have not yet taken on a specific role or shape. These cells are grown in a laboratory using a method called tissue culture. Scientists can manipulate a callus to develop into different plant parts or even a whole new plant.
In simple words: A callus is a mass of plant cells grown in a lab that have not yet specialized into specific tissues.

🎯 Exam Tip: Define callus as an undifferentiated cell mass and mention its origin in tissue culture.

 

Question 34. Define Apomixis?
Answer: Apomixis is a type of reproduction in plants where new individuals form without the usual sexual process. This means it does not involve meiosis (cell division to make gametes) or syngamy (the fusion of male and female gametes). This allows plants to produce offspring that are genetically identical to the parent without needing a partner or seeds.
In simple words: Apomixis is when a plant reproduces without needing sex cells or fertilization, making clones.

🎯 Exam Tip: Explain apomixis as asexual reproduction that bypasses meiosis and syngamy, leading to clones.

 

Question 35. What is Scutellum?
Answer: In monocot seeds like paddy (rice), the embryo has a special shield-shaped cotyledon called the scutellum. This small embryo is found on the side of the main embryonic axis. The scutellum plays a key role in absorbing nutrients from the endosperm and transferring them to the growing embryo.
In simple words: The scutellum is the special shield-shaped cotyledon in monocot seeds that helps feed the embryo.

🎯 Exam Tip: Define scutellum as the shield-shaped cotyledon in monocot seeds and mention its location and function.

 

Question 36. Define Pollinium.
Answer: A pollinium is a special package of pollen grains found in some plants, like Calotropis. In these plants, all the small pollen grains from one part of the flower (microsporangium) stay stuck together as a single unit. This compact structure helps ensure that a large amount of pollen is transferred efficiently during pollination.
In simple words: A pollinium is a group of pollen grains that stick together and are moved as one piece, like in Calotropis.

🎯 Exam Tip: Describe pollinium as a mass of pollen grains that are transferred as a single unit, giving an example like Calotropis.

 

Question 37. What is Amphitropous?
Answer: Amphitropous describes a type of ovule that has a specific curved shape. Its nucellus (the central part of the ovule) is curved like a horseshoe. In this type, the hilum and chalaza (parts of the ovule) are positioned in the middle, giving it a somewhat transverse orientation. A good example is seen in Alismataceae plants. This unique curvature affects how the embryo sac develops and how nutrients are supplied to the growing embryo.
In simple words: An amphitropous ovule is shaped like a horseshoe, with the hilum and chalaza in the middle, found in plants like Alismataceae.

🎯 Exam Tip: Explain amphitropous ovule by describing its horseshoe shape and the relative positions of its parts, providing an example.

 

Question 38. Write the practical application of activation of nucellar tissue.
Answer: Activating nucellar tissue has practical uses, especially in plant breeding. This tissue, or other cells in the ovule, can be stimulated to produce multiple embryos, a process called polyembryony. The plants grown from these nucellar tissues, like in citrus fruits, are better clones for orchards. They are also disease-resistant and virus-free, making them more desirable for farmers compared to regular seedlings. This method offers a powerful way to mass-produce healthy, uniform plants with desired traits.
In simple words: Activating nucellar tissue helps create many embryos, leading to better, disease-free clones, especially useful for fruits like citrus.

🎯 Exam Tip: Discuss polyembryony from nucellar tissue and its benefits for agriculture, such as producing healthy clones and disease-resistant plants.

 

Question 39. Differentiate pineyed flower and thrum eyed flower.
Answer: Pineyed flowers and thrum-eyed flowers are two types seen in plants like Primula, showing a condition called heterostyly. This difference in structure helps prevent self-pollination and promotes cross-pollination.
- **Pineyed flower:** These flowers have a long style (the stalk of the stigma) and a long stigma. Their stamens (pollen-producing parts) are short and located lower down.
- **Thrum-eyed flower:** These flowers have a short style and small stigmatic papillae (the receptive surface). Their stamens are long and are placed higher up in the flower.
In simple words: Pineyed flowers have a long female part and short male parts, while thrum-eyed flowers have short female parts and long male parts.

🎯 Exam Tip: Clearly describe the relative lengths of the style/stigma and stamens for both pineyed and thrum-eyed flowers, and explain how this arrangement aids pollination.

 

Question 40. Differentiate Coleoptile and Coleorhiza.
Answer: Coleoptile and coleorhiza are protective sheaths found in monocot embryos. These structures are crucial for the seedling's successful emergence from the soil, especially in grasses:
- **Coleoptile:** This is a protective sheath that covers the plumule, which is the embryonic shoot. It protects the young shoot as it grows through the soil.
- **Coleorhiza:** This is a protective sheath that covers the radicle (the embryonic root) and its root cap. It protects the young root as it pushes into the soil.
In simple words: Coleoptile protects the young shoot, and coleorhiza protects the young root in monocot seeds.

🎯 Exam Tip: Define both coleoptile and coleorhiza, clearly stating which part of the embryo each one protects.

III. Three Marks

 

Question 1. How does pollen tube grow through a solid style?
Answer: In many dicot plants, the style is solid. The pollen tube grows through this solid style by moving through the spaces between its cells. This process is helped by a special central core of long, specialized cells called transmitting tissue. This tissue functions similarly to the lining of a hollow style, guiding the pollen tube towards the ovule. The transmitting tissue also provides nutrients and chemical signals that help direct the pollen tube's path.
In simple words: The pollen tube grows through the gaps between cells in a solid style, guided by special transmitting tissue.

🎯 Exam Tip: Explain the role of transmitting tissue and intercellular spaces in guiding the pollen tube through a solid style.

 

Question 2. Give the significance of pollen calendar?
Answer: A pollen calendar is important because it shows when different plants produce pollen throughout the year. This information is very helpful for people who suffer from allergies, as they can prepare for seasons when high levels of allergenic pollen, which causes conditions like asthma, bronchitis, fever, and allergic rhinitis, are expected. By knowing when specific pollens are active, individuals can take preventive measures to manage their symptoms.
In simple words: A pollen calendar shows when different plants release pollen, helping people with allergies to prepare and manage their symptoms.

🎯 Exam Tip: Describe a pollen calendar as a seasonal guide for pollen production and explain its benefit for allergy sufferers.

 

Question 3. Comment on Caruncle?
Answer: A caruncle is a fleshy growth that forms from the outer protective layer (integument) of the ovule, specifically near the micropyle (small opening). It is seen in plants like Ricinus communis. This structure often plays a role in seed dispersal, attracting ants that carry the seeds away.
In simple words: A caruncle is a soft growth near the seed's opening, which helps spread seeds by attracting animals.

🎯 Exam Tip: Define caruncle as a fleshy outgrowth near the micropyle and provide an example of a plant where it is found.

 

Question 4. What is perisperm?
Answer: Perisperm is the remaining part of the nucellar tissue (the central part of the ovule) that stays in some mature seeds. Instead of being completely used up by the growing embryo, it acts as a food storage tissue. Examples include black pepper and beetroot seeds. While endosperm is more common for nutrient storage, perisperm serves the same function in specific plant families.
In simple words: Perisperm is leftover nucellar tissue in a seed that stores food, seen in plants like black pepper.

🎯 Exam Tip: Define perisperm as persistent nucellar tissue in a seed and provide common examples like black pepper.

 

Question 5. What is Aril?
Answer: An aril is a colorful, fleshy outgrowth that covers or partially covers a seed. It develops from the funiculus, which is the stalk connecting the ovule to the placenta. Examples of plants with aril include Myristica (nutmeg) and Pithecellobium. The bright colors and fleshy texture of the aril often attract animals, aiding in seed dispersal.
In simple words: An aril is a colorful, fleshy covering on a seed that helps animals spread it, like in nutmeg.

🎯 Exam Tip: Define aril as a fleshy outgrowth from the funiculus that surrounds a seed, providing examples.

 

Question 6. Write about Endosperm?
Answer: The endosperm is a special tissue that develops from the primary endosperm nucleus after fertilization in angiosperms. Its main job is to provide nourishment to the growing embryo inside the seed. Importantly, the zygote often begins to divide and develop into an embryo only after the endosperm has sufficiently formed, ensuring a food supply is ready. Beyond just nutrition, the endosperm also plays a crucial role in regulating the overall development of the embryo. The endosperm stores food reserves like starch, proteins, and oils, which are essential for the embryo's early growth.
In simple words: Endosperm is a special tissue that provides food and regulates the growth of the embryo in a seed.

🎯 Exam Tip: Explain the origin of endosperm, its primary function as a nutritive tissue for the embryo, and its regulatory role.

 

Question 7. Differentiate Endospermous and non-endospermous seeds?
Answer: Seeds can be categorized into two main types based on whether they retain endosperm at maturity:
- **Endospermous seeds:** These seeds keep the endosperm tissue, which serves as their food reserve, even when they are fully mature. They are also known as albuminous seeds. Examples include paddy (rice), coconut, and castor.
- **Non-endospermous seeds:** In these seeds, the endosperm is completely used up by the developing embryo during seed formation. The food reserves are then stored in the cotyledons. These are also known as ex-albuminous seeds. Examples include pea, groundnut, and bean.
The presence or absence of endosperm is a key characteristic used in classifying plant families and understanding their developmental patterns.
In simple words: Endospermous seeds keep food storage tissue, while non-endospermous seeds use it all up during growth.

🎯 Exam Tip: Clearly define and differentiate endospermous (albuminous) and non-endospermous (ex-albuminous) seeds, providing at least two examples for each.

 

Question 8. Comment on Aleurone Tissue.
Answer: Aleurone tissue is a specialized layer of cells that surrounds the endosperm in cereal grains, such as barley and maize. These cells contain sphaerosomes, which are lipid storage bodies. During seed germination, the aleurone layer becomes active and secretes digestive enzymes like amylase and protease. These enzymes break down the stored food (starch and protein) in the endosperm, making it available for the growing embryo. This enzymatic action is vital for mobilizing the stored energy required for the seedling's initial growth.
In simple words: Aleurone tissue is a special layer in cereal seeds that releases enzymes to help the embryo digest stored food during germination.

🎯 Exam Tip: Describe aleurone tissue as a specialized layer in cereals, mentioning its location, contents (sphaerosomes), and its role in secreting enzymes during germination to digest endosperm reserves.

 

Question 9. Mention the other interesting pollinating mechanism of plants?
Answer: Plants have many interesting ways to achieve pollination. Some use a "trap mechanism," like in *Aristolochia*, where insects are temporarily trapped to ensure pollen transfer. Others use a "pitfall mechanism," as seen in *Arum*, where insects fall into a chamber. The *Asclepiadaceae* family uses a "clip or translator mechanism," where pollen is attached to an insect via a clip. Finally, plants in the *Papilionaceae* family may use a "piston mechanism" to push out pollen. These diverse strategies highlight the intricate co-evolutionary relationships between plants and their pollinators.
In simple words: Plants use mechanisms like traps (Aristolochia), pitfalls (Arum), clips (Asclepiadaceae), or pistons (Papilionaceae) to pollinate.

🎯 Exam Tip: List at least three distinct pollination mechanisms with their respective plant examples, focusing on unique adaptations for pollen transfer.

 

Question 10. Grafting is method of production of hybrid plants but not the method of reproduction. Do you agree this statement? Give logic reason for your answer.
Answer: The statement "Grafting is a method of production of hybrid plants but not the method of reproduction" is not entirely accurate. Grafting is an artificial method of **vegetative reproduction**, which is a form of asexual reproduction. It involves joining parts of two different plants (the scion, which is the shoot, and the stock, which is the root system) to grow as one.
While grafting allows combining desirable stem traits from one plant (scion) with favorable root traits from another (stock), it typically results in a single new plant that is genetically identical to the scion. It does not create a true "hybrid" in the genetic sense, which usually implies sexual reproduction between two different parents. So, it is a method of propagation (reproduction) but not for creating true genetic hybrids. Grafting is widely used in horticulture to improve fruit quality, disease resistance, and growth vigor of plants.
In simple words: Grafting is a way to make new plants (reproduction) but it's asexual, not a way to make true genetic hybrids. It combines parts of two plants into one.

🎯 Exam Tip: Explain that grafting is a vegetative reproduction method, not true sexual hybridization. Describe how it joins two plant parts (scion and stock) to combine their desirable characteristics.

 

Question 11. Comment on pollen (nectar) robber?
Answer: A pollen or nectar robber is an animal that takes nectar or pollen from a flower without helping with pollination. For example, some insects might visit a flower like *Amorphophallus*, where they consume pollen and nectar or even lay eggs, but they do so in a way that doesn't transfer pollen from one flower to another. They effectively "rob" the floral rewards without providing the service of pollination. These interactions represent a form of cheating in the plant-pollinator relationship, as the plant invests in rewards without receiving the benefit of reproduction.
In simple words: A pollen or nectar robber is an animal that takes food from a flower but does not help to pollinate it.

🎯 Exam Tip: Define pollen/nectar robbing as taking floral rewards without facilitating pollination, giving an example of an organism that engages in this behavior.

 

Question 12. Describe pseudocopulations?
Answer: Pseudocopulation is a fascinating pollination strategy used by some plants, particularly orchids like the Bee orchid (*Ophrys*). In this process, the flower evolves to look and smell like a female insect. A male insect then attempts to mate with the flower, mistaking it for a female. During this fake mating attempt, pollen gets attached to the male insect, which it then carries to another flower, thus achieving pollination. This mimicry is a highly specialized form of co-evolution, demonstrating how plants can exploit insect behavior for their reproductive success.
In simple words: Pseudocopulation is when a flower looks and smells like a female insect, tricking a male insect into "mating" with it and spreading pollen.

🎯 Exam Tip: Explain pseudocopulation as a mimicry strategy by flowers to attract male insects for pollination through fake mating attempts, using the Bee orchid as an example.

 

Question 13. Write any two differences between male gametophyte and female gametophyte.
Answer: The male and female gametophytes in plants show distinct differences:
**Male Gametophyte:**
1. It is the pollen grain, which develops from a microsporangium.
2. It undergoes two main growth phases: before and after pollination.
3. It typically consists of three cells (a vegetative cell and two male gametes) when mature.
4. All its cells are functional, involved in either growth or fertilization.
**Female Gametophyte:**
1. It is the embryo sac, which develops inside the ovule (megasporangium).
2. It is embedded within the ovule, protected by layers of tissue.
3. It usually consists of seven cells but contains eight nuclei (one central cell with two polar nuclei, one egg cell, two synergids, and three antipodal cells).
4. Its growth takes place entirely inside the megasporangium (ovule).
These structural and developmental differences ensure the distinct roles of male and female reproductive units in plant reproduction.
In simple words: The male gametophyte is the pollen grain with 3 cells, developing outside. The female gametophyte is the embryo sac with 7 cells and 8 nuclei, developing inside the ovule.

🎯 Exam Tip: Provide at least two clear contrasting points between male (pollen grain) and female (embryo sac) gametophytes, covering their origin, cellularity, or location.

 

Question 14. What are the disadvantages of self pollination?
Answer: Self-pollination, while ensuring reproduction, has some significant drawbacks. Firstly, continuous self-pollination over generations can lead to weaker offspring, a phenomenon known as inbreeding depression. Secondly, there is a very low chance of genetic variation, which means it's difficult to produce new species or varieties that might be better adapted to changing environments. Lack of genetic diversity makes populations less resilient to diseases and environmental shifts.
In simple words: Self-pollination can make offspring weaker and reduces the chance of new, stronger plant types forming.

🎯 Exam Tip: List reduced vigor (weaker progeny) and low genetic variation as the primary disadvantages of self-pollination.

 

Question 15. Enlist the disadvantages of cross pollination?
Answer: Cross-pollination, despite its benefits, also has disadvantages. One major drawback is that the process is often uncertain and less reliable because it depends on external factors like wind, water, or animals (pollinating agents). Additionally, plants need to invest energy and resources to develop various structures and rewards (like colorful petals, nectar, and scent) to attract these pollinating agents, which can be metabolically costly. This reliance on external factors can lead to lower reproductive success if pollinators are scarce or environmental conditions are unfavorable.
In simple words: Cross-pollination is uncertain as it relies on outside help, and plants use a lot of energy to attract pollinators.

🎯 Exam Tip: Highlight the uncertainty due to reliance on external agents and the energy cost of attracting pollinators as key disadvantages of cross-pollination.

 

Question 16. Pollination is prerequisite for fertilisation. Discuss?
Answer: Yes, pollination is absolutely necessary for fertilization to occur in plants. Pollination is the process where pollen grains are transferred from the anther to the stigma. This act is crucial because it brings the male gametes (contained within the pollen) close to the female gametes (inside the ovule). Once the pollen reaches the stigma, it can germinate and grow a pollen tube, allowing the male gametes to reach and fertilize the egg cell, leading to the formation of a zygote and eventually seeds and fruits. Without successful pollination, the male and female gametes would never meet, and the entire reproductive cycle would be halted.
In simple words: Pollination must happen first so that male pollen can reach the female egg and start the process of making seeds and fruits.

🎯 Exam Tip: Emphasize that pollination is the crucial step that ensures the male gametes reach the female gametes, enabling fertilization and subsequent seed/fruit development.

 

Question 17. How is the surface of endosperm ? Discuss?
Answer: The surface of the endosperm, which is the nutritive tissue in a seed, can sometimes be uneven or irregular. When the endosperm develops with such an irregular, rumpled, or grooved surface, it is called ruminate endosperm. This unique texture is often caused by the uneven growth of the seed coat or the nucellus. Examples of plants with ruminate endosperm include *Areca catechu* (areca nut), *Passiflora* (passionflower), and *Myristica* (nutmeg). This rumination can increase the surface area for nutrient absorption, potentially benefiting the developing embryo.
In simple words: Some endosperm has an uneven, grooved surface, called ruminate endosperm, which helps absorb nutrients and is seen in plants like nutmeg.

🎯 Exam Tip: Define ruminate endosperm as endosperm with an irregular surface, explain its cause (uneven growth), and provide examples.

 

Question 18. Discuss the functions of Endosperm?
Answer: The endosperm serves several vital functions in a developing seed. Primarily, it acts as the main nutritive tissue, providing essential food reserves (like starch, proteins, and fats) to nourish the growing embryo. Importantly, the zygote often begins to divide and develop into an embryo only after the endosperm has sufficiently formed, ensuring a food supply is ready. Beyond just nutrition, the endosperm also plays a crucial role in regulating the overall development of the embryo. By controlling nutrient flow and signaling, the endosperm ensures proper growth and maturation of the new plant.
In simple words: Endosperm feeds the embryo, helps it grow, and controls its development in a seed.

🎯 Exam Tip: Highlight the endosperm's primary role in nutrition, its regulatory function in embryo development, and its formation timing relative to the zygote.

 

Question 19. Relate the role of cocount as endosperm?
Answer: Coconut is a great example of endosperm at work. The coconut water, inside the fruit, is a type of free nuclear endosperm, meaning it contains many nuclei floating in a liquid without cell walls. This water acts as a rich nutrient medium. As the coconut matures, some of this liquid endosperm gradually becomes cellular, forming the fleshy white coconut meat. This endosperm is known to encourage the growth and differentiation of plant tissues and even whole plantlets (embryoids) in laboratory conditions. The rich nutrient content of coconut endosperm makes it a valuable resource for both natural embryo development and biotechnological applications.
In simple words: Coconut water is liquid endosperm, and the white meat is solid endosperm, both providing rich nutrients for embryo growth.

🎯 Exam Tip: Explain coconut water as free nuclear endosperm and the white meat as cellular endosperm, emphasizing its role as a nutrient-rich medium for embryo development.

IV. Five Marks

 

Question 1. Illustrate the structure of cicer, a dicot seed?
Answer: A dicot seed, such as a chickpea (*Cicer*), has a distinct structure. Each seed is attached to the fruit wall by a stalk called the funiculus. Once detached, this attachment point leaves a scar called the hilum. Below the hilum is a tiny pore called the micropyle, which allows oxygen and water to enter the seed for germination. The seed is protected by a seed coat, which develops from the ovule's integuments. This seed coat consists of two layers: the tough outer layer called the testa, and a thin, inner membranous layer called the tegmen. In some dicots, like peas, the testa and tegmen are fused together. The protective seed coat and the hilum-micropyle complex are crucial for the seed's survival and successful germination.

In simple words: A dicot seed has an outer coat (testa and tegmen), a scar (hilum), a small opening (micropyle), and an embryo with a small shoot (plumule) and root (radicle).

🎯 Exam Tip: Describe the key external and internal features of a dicot seed (hilum, micropyle, seed coat layers), explaining the function of each part.

 

Question 2. Describe the structure of a monocot seed (Ex. Paddy)?
Answer: A monocot seed, like paddy (rice), has a distinctive structure tailored for its single cotyledon. The entire seed is often enclosed within a husk. Inside, the main protective layer is the brown, membranous seed coat, which adheres closely to the grain. The largest part of the seed is the endosperm, which serves as the primary storage tissue for food. The small embryo is located to one side and includes a shield-shaped cotyledon called the scutellum. The plumule (embryonic shoot) is protected by a sheath called the coleoptile, and the radicle (embryonic root) is protected by the coleorhiza, which also covers the root cap. The scutellum is responsible for transferring food from the endosperm to the embryo.
Here is a summary of the monocot seed structure (Paddy):
1. Only one cotyledon
2. Paddy is one-seeded.
3. Seed is enclosed by husk. The brown membranous seed coat closely adheres to grain
4. Scutellum supplies embryo with food from endosperm through epithelium
5. Coleoptile and coleorhiza are seen.
In simple words: A monocot seed like paddy has one cotyledon (scutellum), a protective husk and seed coat, a large food-storing endosperm, and the embryo's shoot and root are protected by coleoptile and coleorhiza.

🎯 Exam Tip: Detail the structure of a monocot seed (e.g., paddy), emphasizing the single cotyledon (scutellum), endosperm, and protective sheaths (coleoptile and coleorhiza).

 

Question 3. In some kinds of plant reproductions male, female gametes are not involved ? Justify? Apomixis.
Answer: Yes, it is true that in some plant reproductions, male and female gametes are not involved. This process is called Apomixis. Apomixis is a type of asexual reproduction in plants where seeds or plantlets are formed without the fusion of male and female gametes, meaning there is no fertilization. The offspring are genetically identical to the parent plant. This ensures consistent traits across generations but limits genetic diversity for adaptation to new environments.
In simple words: Yes, in apomixis, plants reproduce without male or female gametes, creating clones of the parent plant.

🎯 Exam Tip: Define apomixis as plant reproduction without the involvement of gametes or fertilization, explaining that it produces clones of the parent plant.

 

Question 4. Differentiate heterostyly from herkogamy
Answer: Heterostyly and Herkogamy are both mechanisms that promote cross-pollination by preventing self-pollination, but they do so differently. These evolutionary adaptations increase genetic diversity, making plant populations more robust:
- **Heterostyly:** This involves flowers having different lengths of stamens (male parts) and styles (female parts) within the same plant species. For example, in *Primula*, some flowers have long styles and short stamens (pin-eyed), while others have short styles and long stamens (thrum-eyed). Pollination is most effective between organs of matching lengths from different flower types.
- **Herkogamy:** This refers to the physical separation or spatial arrangement of male and female reproductive organs (stamens and stigmas) within the same flower. This physical barrier prevents pollen from the same flower from reaching its own stigma. For example, in *Hibiscus*, the stigma projects far above the stamens, making self-pollination difficult.
In simple words: Heterostyly means different flowers have different lengths of male and female parts, while herkogamy means male and female parts are physically separated within one flower.

🎯 Exam Tip: Distinguish heterostyly based on varying lengths of stamens/styles from herkogamy, which involves physical separation of anthers and stigma within a flower, providing an example for each.

 

Question 5. An entire plant can be produced from a single cell – Justify?
Answer: Yes, an entire plant can indeed be produced from a single plant cell due to a unique property called **totipotency**. Totipotency is the genetic ability of a plant cell to develop into a complete, mature plant under the right conditions. This is a fundamental concept that underlies modern plant biotechnology and cloning.
This principle is utilized in techniques like:
(i) **Tissue Culture:** In this method, a small piece of plant tissue or even a single cell is grown in a special nutrient medium in a controlled laboratory environment. Under these conditions, the cell can dedifferentiate, form a mass of undifferentiated cells (callus), and then redifferentiate to produce roots, shoots, and eventually a whole plant. For example, F.C. Steward famously grew an entire carrot plant from a single phloem parenchyma cell.
(ii) **Micropropagation:** This is a technique that uses tissue culture methods to rapidly produce a large number of genetically identical plants from a small plant part or cell.
In simple words: Yes, because plant cells have 'totipotency,' meaning one cell can grow into a whole plant, as shown in tissue culture and micropropagation.

🎯 Exam Tip: Define totipotency as the ability of a single plant cell to form an entire plant. Justify this by explaining tissue culture and micropropagation techniques, mentioning a key example like Steward's work with carrots.

 

Question 6. Elaborate an account on the T.S of anther.
Answer: The anther, the part of the stamen that produces pollen, has a complex structure in cross-section (T.S.) involving several layers. Each layer of the anther wall plays a specialized role, ensuring the proper development and release of viable pollen:
1. **Anther Wall:** This wall is composed of four main layers:
    a) **Epidermis:** This is the outermost, single protective layer of the anther. Its cells can divide (anticlinal division) to accommodate the growing internal tissues.
    b) **Endothecium:** Located just beneath the epidermis, this layer consists of a single row of radially elongated cells. Its tangential walls contain cellulose and sometimes lignin bands, giving it a hygroscopic (water-absorbing) nature. This hygroscopic property, along with a specialized non-thickened region called the stomium, is crucial for the dehiscence (splitting open) of the anther, releasing pollen.
    c) **Middle Layers:** These are typically two to three layers of cells found between the endothecium and the tapetum. They are usually short-lived (ephemeral) and often disintegrate or get crushed as the anther matures.
    d) **Tapetum:** This is the innermost layer of the anther wall, surrounding the sporogenous tissue. It has a dual origin. The tapetum is highly nutritive, providing essential nourishment to the developing sporogenous tissue, microspore mother cells, and the forming microspores. Its cells can be uninucleate or multinucleate, often becoming polyploid. It contributes materials for the pollen wall, including sporopollenin, pollenkitt, and tryphine. The tapetum also influences the fertility or sterility of the pollen grains and exists in two types: secretory and invasive.

In simple words: The anther has four main layers: the outer epidermis, the endothecium (which helps it open), the middle layers (that disappear), and the tapetum (which feeds the growing pollen).

🎯 Exam Tip: Describe the four layers of the anther wall (epidermis, endothecium, middle layers, tapetum) and their specific functions, highlighting how each contributes to pollen development and release.

 

Question 6. Elaborate an account on the T.S of anther.
Answer: The anther wall has several layers, each with a specific function in pollen development.
(a) Epidermis:
This is a single protective layer on the outside. Its cells divide in a specific way (anticlinal division) to keep up with the growing inner tissues.
(b) Endothecium:
This layer has cells that are elongated in a radial direction. Bands of cellulose and sometimes lignin are found in their tangential walls. The cells where the two sporangia meet (called the stomium) do not have these thick bands. The endothecium's ability to absorb moisture helps the anther open up (dehiscence) when it's mature, releasing the pollen. Its hygroscopic nature is crucial for pollen dispersal.
(c) Middle layer:
There are typically two to three layers of these cells, located just after the endothecium. They are short-lived and usually break down or get crushed as the anther matures.
(d) Tapetum:
This is the innermost layer of the anther wall. It has a dual origin, coming from both the outer wall layer and the connective tissue inside the anther. The tapetum provides essential nutrients to the developing microspores and microspore mother cells. Its cells can have one or more nuclei, often with multiple sets of chromosomes (polyploid). The tapetum also helps form wall materials like sporopollenin, pollen kitt, and tryphine. It plays a role in determining if a plant's pollen will be fertile or sterile. There are two main types: secretory and invasive tapetum.
The solution mentions several diagrams related to the anther's structure, including a diagrammatic view, a view under a microscope, and illustrations of the pollen tetrad stage and microspore stage. These diagrams visually explain the different layers and developmental stages described above, such as the epidermis, endothecium, middle layer, tapetum, stomium, and connective tissue. These visual aids are key to understanding the morphology of the anther.
2. Anther cavity:
This space is filled with young microspores or mature pollen grains. The microspore mother cells divide by meiosis to form the microspores.
3) Connective:
This is a column of sterile tissue that separates the anther lobes. It is surrounded by the anther lobe and contains vascular tissue, which provides support and nutrients.
In simple words: The anther has different layers, like an outer skin (epidermis), a moisture-absorbing layer (endothecium), a temporary middle layer, and an inner feeding layer (tapetum). Each layer helps pollen grow and get released. Diagrams usually show these parts clearly.

🎯 Exam Tip: Remember the four main layers of the anther wall: epidermis, endothecium, middle layers, and tapetum, along with their primary functions. Focus on how the tapetum provides nourishment and the endothecium aids in dehiscence.

 

Question 7. How does the male gametophyte develop?
Answer: The development of the male gametophyte involves several steps, starting from the microspore. The process includes the formation of pollen grains and their subsequent growth.
A haploid microspore is the very first cell of the male gametophyte. This development takes place inside the microsporangium, which is part of the anther. The nucleus of the microspore divides into two smaller nuclei: a large vegetative nucleus and a smaller generative nucleus. At this stage, when there are two cells, the pollen is released from the anther. In some plants, the generative cell then divides to form two male gametes. The male gametophyte continues to grow once the pollen lands on the correct stigma. The pollen absorbs moisture and swells. The inner wall of the pollen (intine) grows out through a small opening (germ pore) to form a pollen tube. Finally, at the two-celled stage, the generative cells divide to form two male cells, which are then delivered to the stigma.
The solution contains diagrams illustrating the various stages of pollen grain development. These include views of the pollen grain with its exine (outer layer), intine (inner layer), nucleus, and germ pore (a); the pollen grain with a vacuole and nucleus (b); the nucleus dividing (c); the formation of a vegetative cell and generative cell (d); and finally, the pollen tube with the generative nucleus and tube nucleus (e), as well as a diagram showing the male gametes and tube nucleus (f) and (g). These diagrams visually represent the entire process from microspore to mature male gametophyte, highlighting the internal changes and structures at each step.
In simple words: The male gametophyte starts from a small microspore cell. This cell grows, and its inner part divides into a larger feeding cell and a smaller cell that will make two male cells. When pollen lands on the right spot, it grows a tube, and the male cells travel through it.

🎯 Exam Tip: Remember the two key stages of male gametophyte development: the microspore stage (before pollination) and the pollen tube stage (after pollination). Focus on the roles of the vegetative cell and the generative cell, and how the pollen tube facilitates the delivery of male gametes.

 

Question 8. Ovules are of many types based on the orientation, form, position of micropyle with respect to funicle, chalaza – discuss?
Answer: Ovules come in several forms, each named for how its parts (micropyle, funicle, chalaza) are arranged. This orientation is important for fertilization.
1. Orthotropous:
In this type, the micropyle is at the top (distal end). Both the funicle (stalk) and the chalaza (base) lie in a straight vertical line. An example of a plant with orthotropous ovules is Piperaceae.
2. Anatropous:
Here, the body of the ovule is completely inverted, turning 180 degrees. As a result, the micropyle and the funicle are very close to each other. This is common in dicots and monocots.
3. Hemianatropous:
In this ovule, the body is positioned across, meaning it is transverse. The funicle is at a right angle to the body of the ovule. Primulaceae is an example of plants with hemianatropous ovules.
4. Campylotropous:
The body of the ovule is curved, especially at the micropylar end. The embryo sac inside is also curved. The hilum, micropyle, and chalaza are all close to each other, but the ovule's curvature makes them less aligned than in anatropous ovules. Leguminosae is an example.
5. Amphitropous:
This type has a shorter distance between the hilum and the chalaza. The nucellus (central tissue) is shaped like a horseshoe, which gives the ovule its characteristic appearance. Alismataceae is an example.
6. Circinotropous (Ex. Cactaceae):
In this type, the funicle is very long and completely surrounds the ovule, making a circle. This is often seen in Cactaceae. A diagram is provided in the source which shows all these ovule types (Orthotropous, Anatropous, Hemianatropous, Campylotropous, Amphitropous, Circinotropous) visually to illustrate their different orientations and shapes.
In simple words: Ovules, which grow into seeds, have different shapes and ways they are attached inside the flower. They can be straight, upside down, bent, or even coiled, depending on where their opening, attachment stalk, and base are located.

🎯 Exam Tip: When differentiating ovule types, focus on the relative positions of the micropyle, funicle, and chalaza. Visualizing these arrangements is key to remembering each type.

 

Question 9. How does the monosporic embryosac develop?
Answer: The monosporic embryo sac develops from a single functional megaspore through a series of mitotic divisions. This process is crucial for the formation of the female gametophyte.
The functional megaspore is the initial cell of the embryo sac, also known as the female gametophyte. This megaspore starts to grow longer along the micropylar-chalazal axis. Its nucleus then undergoes three rounds of mitosis (cell division), but without the formation of cell walls between the new nuclei. As a result, a central vacuole grows larger, pushing the nuclei towards the opposite ends of the cell. After two mitotic divisions, four nuclei are formed at each pole. These eight nuclei are all contained within a single shared cytoplasm. Out of the four nuclei at the micropylar end, three form the egg apparatus (egg cell and two synergids), and the fourth becomes the lower polar nucleus. The two polar nuclei (one from each pole) then join together to form a secondary nucleus. Thus, a mature embryo sac usually has seven cells but eight nuclei. The source includes a diagram which illustrates this development from an archesporial cell, through megaspore mother cell, functional megaspore, 2-nucleate stage, 4-nucleate stage, to the final 8-nucleate stage, showing the synergids, egg, polar nucleus, and antipodal cells.
In simple words: A special cell in the plant, called a megaspore, grows and divides three times without making new cell walls. This creates a big cell with eight nuclei. These nuclei then arrange themselves to form the egg and other important cells needed for a new plant to start growing.

🎯 Exam Tip: Remember that "monosporic" means development from a single megaspore. Focus on the three mitotic divisions without cytokinesis and the final 7-celled, 8-nucleate structure of the mature embryo sac.

 

Question 10. Enlist the contrivances for crosspollination ?
Answer: Cross-pollination, where pollen moves between different plants, is promoted by various mechanisms that prevent self-pollination. These mechanisms encourage genetic diversity in plants.
1) Dicliny or Unisexuality:
In unisexual flowers, only cross-pollination is possible because each flower has either male or female parts, not both. This forces pollen to come from a different flower.
i) Monoecious (Ex. coconut):
Male and female flowers are found on the same plant. Self-pollination of the individual flower is prevented by the separation of sexes into different flowers. However, a plant can still pollinate itself (geitonogamy).
Dioecious:
Male and female flowers are located on separate plants. This means both self-pollination (autogamy) and pollination between flowers on the same plant (geitonogamy) are prevented, ensuring only cross-pollination happens.
2) Monocliny or Bisexuality:
These flowers have both male and female parts but have ways to stop self-pollination.
i) Dichogamy:
This occurs when the anthers (male parts) and stigma (female parts) of a flower mature at different times.
Protandry (Ex. Helianthus): In protandrous flowers, the stamens (male parts) mature and release pollen before the stigma (female part) is ready to receive it.
Protogyny (Ex. Aristolochia): In protogynous flowers, the stigma matures and becomes receptive before the stamens release their pollen.
ii) Herkogamy:
This is a physical barrier that prevents self-pollination due to the specific arrangement of the stamens and stigma within the flower. For example, in Hibiscus, the stigma extends far above the stamens, making self-pollination difficult. The source provides a diagram showing the "Herkogamy - Gloriosa" arrangement, illustrating how the stigma and anthers are positioned to prevent direct contact, thus promoting cross-pollination.
iii) Heterostyly:
This refers to flowers having different lengths of stamens and styles. Pollination can only happen effectively between flowers that have reproductive organs of matching lengths. This mechanism encourages cross-pollination by ensuring genetic exchange between different floral forms.
a) Distyly (Ex. Primula):
This involves two types of flowers: "thrum-eyed" flowers with short styles and tall stamens, and "pin-eyed" flowers with long styles and short stamens. The anthers of thrum-eyed flowers and the stigma of pin-eyed flowers are at the same height, which helps in efficient cross-pollination. The source provides diagrams for "Protandry - Cleordendrum" and "Protogyny - Scrophularia" (a and b), showing different lengths of stamens and styles to prevent self-pollination.
b) Tristyly (Ex. Lythrum):
This involves three different forms of flowers, differing in the length of their styles and stamens. Flowers of one type cannot pollinate themselves and must pollinate one of the other two types.
iv) Self sterility / Self incompatibility:
This is a genetic mechanism where a flower's own pollen is unable to grow or fertilize the ovules of the same flower. For example, in Passiflora, the pollen grain from a flower cannot germinate on its own stigma, preventing self-pollination despite being a bisexual flower.
In simple words: Plants have clever ways to make sure their pollen mixes with pollen from other plants, not just their own. This includes having separate male and female flowers, or having male and female parts mature at different times, or even positioning them in a way that self-pollination is physically hard. Some plants even have a built-in block so their own pollen can't work.

🎯 Exam Tip: Categorize mechanisms into those based on spatial separation (like unisexuality, heterostyly, herkogamy) and temporal separation (dichogamy). Always provide a plant example for each mechanism to demonstrate understanding.

 

Question 11. Enlist the characteristics of Anemophilous
Answer: Anemophilous flowers are specially adapted for wind pollination, meaning they have features that make it easy for the wind to carry their pollen. These characteristics help ensure successful reproduction without needing insects or animals.
Here are the typical characteristics:
• Flowers are often found in pendulous (hanging) or catkin-like structures, or spike inflorescences, which allow pollen to be easily caught by the wind.
• The inflorescence axis elongates, raising the flowers above the leaf level so that pollen dispersal is not hindered by foliage.
• The perianth (petals and sepals) is either very small or completely absent, as bright colors or nectar are not needed to attract pollinators.
• Flowers are small, do not secrete nectar, and are not scented, because they don't need to attract animals.
• Filaments (stalks supporting the anthers) are long, extended, and versatile, allowing the anthers to sway freely and release pollen effectively.
• These flowers produce an enormous quantity of pollen grains to increase the chances of successful pollination, as wind pollination is often inefficient.
• The pollen is minute, light, and dry, making it easy for the wind to carry it over long distances.
• Anthers burst violently to release pollen grains, as seen in plants like Urtica, ensuring wide dispersal.
• Stigmas are often protruding, feathery, or branched, providing a large surface area to catch wind-borne pollen.
• Flowers usually develop before leaves appear, which helps the pollen travel without being blocked by foliage, ensuring early and effective pollination.
In simple words: Wind-pollinated flowers are simple, often hanging, and don't have bright colors or smells. They make lots of tiny, light pollen and have long, feathery parts to catch pollen from the air.

🎯 Exam Tip: Focus on adaptations that reduce weight (small flowers, no nectar) and increase exposure (elongated axis, versatile anthers, feathery stigmas) for efficient wind dispersal and capture.

 

Question 12. Explain pollination in maize?
Answer: Pollination in maize (Zea mays) is an example of anemophily, where wind is the primary agent for pollen transfer. Maize has specific features that make this process efficient.
• Maize plants are monoecious, meaning both male and female flowers are on the same plant, but they are unisexual, with separate male and female flowers.
• The male inflorescence, called the tassel, is located at the top (terminal) of the plant.
• The female inflorescence, called the cob, grows at a lower, lateral position on the stem.
• While pollen grains are heavy, they can still be carried by the wind, especially over short distances, as they are not designed for insect transport.
• The male inflorescence (tassel) is shaken by the wind, causing the released pollen to fall vertically. This makes it easy for the pollen to reach the female flowers below.
• The female inflorescence (cob) has very long stigmas (up to 23 cm) that project beyond the protective leaves. These long, silky stigmas are designed to efficiently catch the pollen falling from the tassel. A diagram showing "Pollination in Zea mays" illustrates the placement of the male inflorescence (tassel) at the top and the female inflorescence (cob) with its silks (stigmas) lower down, making the process clear.
In simple words: Maize uses wind for pollination. The male flowers are at the top and release pollen that falls downwards. The female flowers are lower down and have long, sticky hairs to catch this falling pollen.

🎯 Exam Tip: Highlight that maize is monoecious but has separate male (tassel) and female (cob with silks) flowers. Emphasize the role of wind and the long, exposed stigmas in capturing pollen.

 

Question 13. What do you know about the lever mechanism of pollination? Explain?
Answer: The lever mechanism of pollination is a specialized method found in certain flowers, like Salvia, which uses insects (usually bees) to ensure accurate pollen transfer. This mechanism makes sure the bee picks up and drops off pollen in the right spot.
• Salvia flowers are specifically adapted for pollination by bees.
• The flower has a bilabiate corolla, meaning it has two lips, and two stamens (male reproductive parts).
• Each anther (the part of the stamen that holds pollen) has an upper fertile lobe and a lower sterile lobe. These two lobes are separated by a long connective tissue, allowing the anthers to swing freely.
• When a bee visits the flower to collect nectar, it pushes against the lower sterile lobe of the connective. This action causes the upper fertile lobe of the stamen to swing down like a lever.
• As the fertile lobe descends, it dusts the bee's back with pollen. This ensures that the bee carries pollen away from the flower.
• When the same bee then visits another Salvia flower, it will again push the lever mechanism. This time, the pollen on its back is brushed against the stigma of the new flower, achieving cross-pollination. The diagram provided in the source illustrates this process, showing the bee's interaction with the pistil (female part) and anther (male part), how pollen gets dusted on the bee's body, and then transferred to the stigma of another flower.
In simple words: In some flowers like Salvia, bees trigger a special lever. When a bee lands, the lever moves and puts pollen on its back. When the bee visits another flower, the lever makes sure that pollen rubs off onto the new flower's sticky part, helping in pollination.

🎯 Exam Tip: Focus on the "lever" action where the bee's weight on the sterile lobe causes the fertile lobe to deposit pollen. This is a classic example of mechanical adaptation for specific insect pollination.

 

Question 14. Describe the development of Dicot embryo?
Answer: The development of a dicot embryo begins after fertilization and involves a series of organized cell divisions and differentiation, leading to the formation of a miniature plant within the seed. This process ensures the proper formation of all essential parts of the future plant.
• The embryo starts to develop at the micropylar end of the embryo sac, which is the end where the pollen tube enters.
• The zygote, which is the first cell of the embryo, undergoes a transverse division, splitting into two cells.
• This division forms an upper terminal cell and a lower basal cell.
• Further divisions in the zygote, specifically in the terminal cell, lead to the formation of the actual embryo. The basal cell often forms a suspensor that pushes the embryo deeper into the endosperm.
• Before reaching full maturity, the embryo passes through distinct developmental stages, including the globular stage (a ball of cells), the heart-shaped stage, and the torpedo-shaped stage.
• A mature dicot embryo has a radicle (embryonic root), two cotyledons (seed leaves), and a plumule (embryonic shoot). The plumule develops into the future stem and leaves, while the radicle develops into the root system. The source provides a comprehensive diagram showing the development of a dicot embryo from a zygote through 2-celled, 4-celled, globular, heart-shaped, and mature stages, highlighting structures like the embryonal mass, hypophysis, suspensor, plumule, cotyledons, radicle, and root cap.
In simple words: After fertilization, the single-celled zygote in a dicot plant divides many times. It goes through stages like a ball, then a heart, and finally forms a tiny plant with two seed leaves, a shoot, and a root, all inside the seed.

🎯 Exam Tip: Key stages in dicot embryo development are globular, heart-shaped, and torpedo-shaped. Remember the final structure: radicle, plumule, and two cotyledons. The suspensor's role in pushing the embryo into the endosperm is also important.

 

Question 15. Summarise the whole life cycle of an Angiosperm plant in the form of schematics diagram.
Answer: The life cycle of an angiosperm (flowering plant) involves an alternation of generations, switching between a dominant sporophyte stage and a reduced gametophyte stage. This ensures both sexual and asexual reproduction aspects are covered.
The sporophyte is the main plant we see, which produces flowers. Inside the flowers, male and female reproductive parts develop. The male part (anther) produces microspores, which become pollen grains (male gametophytes). The female part (ovule) produces megaspores, which develop into the embryo sac (female gametophyte containing the egg). Pollination transfers pollen to the stigma. After that, the pollen tube grows, and fertilization occurs when male gametes fuse with the egg and central cell (double fertilization). This forms a zygote (which grows into an embryo) and an endosperm (food for the embryo). The ovule then becomes a seed, and the ovary develops into a fruit. When the seed germinates, a new sporophyte plant grows. This entire cycle ensures the continuation of the species. A schematic diagram would typically illustrate these stages, from flower to seed and back to flower, showing key structures like the stigma, style, ovary, ovule, sepal, petal, fruit, seed, plumule, cotyledon, testa, and radicle, as seen in a general plant diagram.
In simple words: An angiosperm's life cycle goes from a plant with flowers (sporophyte) to tiny male and female parts (gametophytes). Pollen meets the egg, makes a seed, and the seed grows into a new plant.

🎯 Exam Tip: Focus on the alternation between the sporophyte (plant itself) and gametophyte (pollen, embryo sac) generations. Highlight double fertilization as a unique feature of angiosperms and the development of fruit and seed from the flower parts.

 

Question 16. Explain epihy drophily with an example?
Answer: Epihydrophily is a specialized type of water pollination where pollen grains float on the water surface to reach the stigma of female flowers. This method is common in aquatic plants that need to pollinate at the water level.
Pollination in *Vallisneria* is a classic example of epihydrophily. *Vallisneria* is a submerged, rooted hydrophyte, meaning it lives underwater with roots in the soil. During the time of pollination, the female flowers rise to the water surface on long, coiled stalks. The female flower has a cup-shaped depression, which helps in catching pollen. Meanwhile, the male flowers detach from the plant and float freely on the water surface. These detached male flowers then get trapped in the depression of the female flower. This contact allows the pollen from the male flower to be transferred to the stigma of the female flower, achieving pollination. After pollination, the stalk of the female flower coils up again, pulling the developing fruit back underwater to mature. The provided diagram likely illustrates this entire process, showing the submerged plant, the male flowers floating on the surface, the female flower rising with its coiled stalk, and the interaction at the water surface for pollination.
In simple words: Epihydrophily is when water carries pollen on its surface. For example, in *Vallisneria*, male flowers float to the top and release pollen. Female flowers rise to the surface with a cup-like shape to catch this floating pollen.

🎯 Exam Tip: Remember that epihydrophily involves pollen floating *on* the water surface. *Vallisneria* is the classic example, so focus on the coiling/uncoiling of the female flower stalk and how male flowers reach the surface.

 

Question 17. Enlist the advantages, disadvantages of conventional methods of vegetative propagation?
Answer: Conventional methods of vegetative propagation have both benefits and drawbacks.

Advantages:

• Plants produced are all the same genetically, ensuring desired traits are passed on.
• New plants can grow quickly from parts of the parent plant.
• This method helps propagate plants that have few or no seeds, or seeds that do not sprout easily.
• It is a cost-effective way to grow plants, for example, potatoes (Solanum tuberosum).
• It allows growing plants with good traits like being resistant to diseases and producing a lot of yield through techniques like grafting. This method is very useful for gardeners and farmers who want to quickly grow many identical plants.

Disadvantages:

• If the parent plant has a virus or disease, all new plants will also have it, leading to widespread infection.
• Large plant parts used for propagation, like whole stems or branches, can be hard to move and manage.

In simple words: This way of growing plants helps make many exact copies quickly, especially those without good seeds or with special features. But, diseases can easily spread to all new plants, and handling big plant pieces can be difficult.

🎯 Exam Tip: When listing advantages and disadvantages, always aim for at least two points for each category and provide relevant examples to support your answer for full marks.

 

Question 18. Differentiate biosporic megaspore development from tetrasporic development.
Answer: Here is how biosporic and tetrasporic megaspore developments are different:

Biosporic Megaspore Development:

• In this type, only two out of the four megaspores produced take part in forming the embryo sac.
• A common example where this occurs is the onion plant (Allium).

Tetrasporic Megaspore Development:

• Here, all four megaspores formed from the mother cell contribute to the formation of the embryo sac.
• An example of this is seen in the Peperomia plant. These different development patterns show the diverse ways plants ensure the next generation's growth.

In simple words: Biosporic means two megaspores form the embryo sac, like in onions. Tetrasporic means all four megaspores form it, like in Peperomia.

🎯 Exam Tip: For differentiation questions, always present the comparison in clear, distinct points for each category to highlight the differences effectively.