RBSE Solutions Class 12 Biology Chapter 1 Reproduction in Angiospermic Plants

RBSE Class 12 Biology Chapter 1 Multiple Choice Objective Questions

Question 1. Plant body in angiosperms is -
(a) Diploid sporophyte
(b) Haploid sporophyte
(c) Diploid gametophyte
(d) Haploid gametophyte
Answer: (a) Diploid sporophyte
In simple words: The main plant body of flowering plants, called angiosperms, has two sets of chromosomes, making it a diploid sporophyte.

🎯 Exam Tip: Remember that the sporophyte generation is typically dominant and diploid in higher plants like angiosperms, while the gametophyte is reduced and haploid.

Question 2. Plant part used for vegetative reproduction is called -
(a) Calyx
(b) Corolla
(c) Gynoecium
(d) All of the options
Answer: (d) All of the options
In simple words: Different parts of a flower like the calyx, corolla, or gynoecium can sometimes be used for vegetative reproduction, depending on the plant type.

🎯 Exam Tip: Vegetative reproduction involves growing new plants from non-sexual plant parts. While calyx, corolla, and gynoecium are floral parts, consider how they might be specially adapted for this in specific plant species.

Question 3. Vegetative Propagation by tuber occurs in -
(a) Murraya
(b) Potato
(c) Bryophylluni
(d) Onion
Answer: (b) Potato
In simple words: Potato plants reproduce vegetatively using their tubers, which are special underground stems with buds that can sprout new plants.

🎯 Exam Tip: Remember common examples of vegetative propagation: potato for tubers, Bryophyllum for leaves, and onion for bulbs.

Question 4. Artificial vegetative propagation is done by Cutting in?
(a) Sugarcane
(b) Jasmine
(c) Mogra
(d) All of the options
Answer: (d) All of the options
In simple words: Taking cuttings to grow new plants is an artificial method that works well for sugarcane, jasmine, and mogra plants.

🎯 Exam Tip: Cutting is a simple and widely used artificial propagation method. It's important to know specific plant examples that respond well to this technique.

Question 5. A flower is modified -
(a) Root
(b) Shoot
(c) Leaves
(d) Root tip
Answer: (b) Shoot
In simple words: A flower is essentially a modified shoot, meaning it is a specialized stem with changed leaves that help with reproduction.

🎯 Exam Tip: Understand the evolutionary origin of flowers. They are derived from shoots, and their components are modified leaves adapted for reproduction.

RBSE Class 12 Biology Chapter 1 Very Short Answer Questions

Question 1. Explain different parts or whorls of a flower.
Answer: A typical flower has four main parts, arranged in circles called whorls. These are the calyx, corolla, androecium, and gynoecium. The calyx (outermost green leaf-like parts) and corolla (colorful petals) are called accessory whorls because they help protect the flower and attract pollinators. The androecium (male reproductive part) and gynoecium (female reproductive part) are called essential or necessary whorls because they are directly involved in reproduction.
In simple words: A flower has four main parts: calyx, corolla, androecium, and gynoecium. Calyx and corolla help the flower, while androecium and gynoecium are needed for making new seeds.

🎯 Exam Tip: Clearly list the four whorls and specify which ones are "accessory" (non-essential for reproduction) and which are "essential" (directly involved in reproduction).

Question 3. How does vegetative propagation is done in rose and mogra?
Answer: In rose plants, new plants are grown using stem cuttings, where a piece of the stem is planted to develop roots and shoots. For jasmine, new plants are grown using the mound layering method, which involves covering a part of the stem with soil while it's still attached to the parent plant, allowing it to root before being separated.
In simple words: Roses are grown by cutting stems. Jasmine plants are grown by mound layering, where a stem is covered with soil until it grows roots, then cut from the main plant.

🎯 Exam Tip: Be precise about the specific vegetative propagation method used for each plant. For rose, it's stem cutting, and for jasmine (or mogra, as per question), it's mound layering.

Question 4. Explain clearly about Cutting, Grafting and Layering techniques.
Answer:1. **Cutting:** This technique involves taking a piece of a plant, like a stem or leaf, and planting it in soil or water to grow new roots and shoots, forming a new plant. Plant hormones like IAA are often used to help the roots grow faster. 2. **Grafting:** In grafting, two different plant parts from distinct plants are joined together so they grow as one. A shoot (called the scion) from a plant with desired traits is attached to the rooted stem (called the stock) of another plant. This creates a new plant that combines features from both. 3. **Layering:** This method encourages a stem to grow roots while it's still attached to the parent plant. A part of the stem is covered with soil or a moist material. Once roots form on that part, it's cut from the main plant and grown on its own.
In simple words: 1. **Cutting:** You take a piece of a plant, plant it, and it grows new roots. 2. **Grafting:** You join a branch from one plant onto the rooted stem of another plant to make a new combined plant. 3. **Layering:** You make a part of a plant's stem grow roots while it's still connected to the parent, then you cut it off to become a new plant.

🎯 Exam Tip: For each technique, define it clearly and mention its main purpose or a key feature (e.g., IAA for cuttings, scion/stock for grafting, roots while attached for layering).

Question 5. Differentiate between sexual reproduction and asexual reproduction.
Answer:**Sexual Reproduction:** In flowering plants (angiosperms), this process involves two key steps: meiosis (a type of cell division that reduces chromosome number) and fertilization (the fusion of male and female reproductive cells). It leads to the formation of seeds. Because genetic material from two parents combines, the offspring produced through sexual reproduction show genetic differences and variations from their parents.
**Asexual Reproduction:** This method creates new plants without meiosis or fertilization. It only involves mitotic cell divisions. As a result, the new plants are genetically identical to the parent plant, essentially clones.
In simple words: **Sexual Reproduction:** Uses two parent cells, involves mixing genes, and makes seeds. New plants are different from parents. **Asexual Reproduction:** Uses only one parent cell, doesn't mix genes, and makes exact copies of the parent plant.

🎯 Exam Tip: Focus on the key differences: involvement of gametes/fertilization, type of cell division (meiosis vs. mitosis), and genetic similarity/variation of offspring.

Question 7. Explain vegetative propagation by leaves.
Answer: While most leaves don't help in growing new plants, some specific plants can use them for vegetative propagation. For example, in Bryophyllum (also known as "mother of thousands"), small new buds or plantlets grow along the edges of its leaves. When these tiny plantlets fall off the main leaf and land on the soil, they can grow into completely new, independent plants.
In simple words: Usually, leaves don't make new plants. But in some plants like Bryophyllum, small baby plants grow on the leaf edges. When these fall, they become new plants.

🎯 Exam Tip: The key example for leaf propagation is Bryophyllum. Remember to mention the adventitious buds forming along the leaf margins.

Question 8. Differentiate between 'stock' and 'scion'.
Answer: When performing grafting, two distinct parts are joined to create a single plant. The **scion** is the part of the plant that has the desired characteristics, usually a shoot or a bud, which is inserted onto another plant. The **stock** is the lower part of the grafted plant, which is already rooted in the soil. It provides water, minerals, and a support system for the scion. The stock usually comes from a plant that is strong or resistant to diseases.
In simple words: In grafting, the **scion** is the top part you want to grow, like a branch with good fruit. The **stock** is the bottom part with roots, which provides water and support to the scion.

🎯 Exam Tip: Clearly define both terms and explain their roles in the grafting process, emphasizing that the scion has desirable traits and the stock provides support.

RBSE Class 12 Biology Chapter 1 Short Answer Questions

Question 1. What is Agamospermy?
Answer: Agamospermy is a special type of asexual reproduction that occurs in flowering plants. In this process, seeds are produced without the usual fusion of male and female reproductive cells (gametes) and without fertilization. The embryo inside these seeds doesn't come from a fertilized egg (zygote) but develops directly from a diploid egg cell, meaning it has a full set of chromosomes from the start.
In simple words: Agamospermy is when flowering plants make seeds without needing sex cells to join. The baby plant inside grows from an unfertilized egg that already has all its genes.

🎯 Exam Tip: Emphasize that agamospermy is asexual reproduction, seeds are formed without gamete fusion, and the embryo develops from a diploid egg, not a zygote.

Question 2. Explain various methods of grafting.
Answer: Grafting involves joining parts of two plants so they grow as one. Here are some methods: 1. **Whip or Tongue Grafting:** This is used when the scion (the upper part) and the stock (the lower, rooted part) are about the same thickness. Both are cut diagonally, then a V-shaped cut is made in the stock and a matching cut in the scion. These cuts are fitted together tightly and sealed with grafting wax to help them join. 2. **Wedge Grafting:** This method is also used when the scion and stock have similar diameters. A V-shaped cut is made in the stock, and a wedge-shaped cut is made at the bottom of the scion. The scion is then firmly inserted into the stock's cut, and the joint is sealed with wax. 3. **Crown Grafting:** This technique is used when the stock is much thicker than the scion. The bark of the thick stock is cut downwards. A small, cut branch (scion) is then inserted into this slit in the bark and tied tightly. The entire wound area is then covered with grafting wax to protect it and help it heal.
A-C. Grafting in mango: A. Stock and scion cut obliquely, B-C., Stock and scion joined together
In simple words: We join parts of two plants in different ways: 1. **Whip Grafting:** Cut both plant parts diagonally and fit them together, then tie them. 2. **Wedge Grafting:** Make a V-shape in the bottom plant and a matching wedge-shape in the top part, then push them together and seal. 3. **Crown Grafting:** Cut into the bark of a thick bottom plant and push a smaller branch into the cut, then tie and seal it.

🎯 Exam Tip: When explaining grafting methods, describe the type of cut, the relative sizes of stock and scion, and the key steps involved for each method.

Question 3. Explain in brief vegetative reproduction by stem.
Answer: Many plants can reproduce using their stems, which are often modified for this purpose. These modified stems include structures like tubers (e.g., potato), rhizomes (e.g., ginger), corms (e.g., Colocasia), bulbs (e.g., onion), runners (e.g., grass), and offsets (e.g., water hyacinth). These stems have special points called nodes and spaces between them called internodes. When conditions are right, the buds found at these nodes can grow and develop into entirely new, independent plants.
In simple words: Many plants grow new plants from special stems like potatoes (tubers), ginger (rhizomes), or onions (bulbs). These stems have buds that can sprout new plants when conditions are good.

🎯 Exam Tip: List and briefly explain the different types of modified stems (tuber, rhizome, corm, bulb, runner, offset) and provide a common plant example for each.

Question 4. Write a note on advantages of vegetative propagation.
Answer: Vegetative propagation offers several benefits for growing plants: 1. **Cost-Effective and Easy:** It's often an inexpensive and simple way to produce many new plants quickly. 2. **For Seedless Plants:** This method is crucial for plants like bananas, grapes, roses, and chrysanthemums, which either don't produce viable (growable) seeds or don't produce seeds at all. It's the only way to propagate these species. 3. **Genetic Uniformity:** A significant advantage is that all new plants created this way are exact genetic copies (clones) of the parent plant. This ensures that desirable traits, like specific fruit quality or flower color, are maintained perfectly across generations.
In simple words: Vegetative propagation is easy and cheap. It helps grow plants that don't make good seeds, like bananas. All new plants are exactly like the parent, keeping good qualities.

🎯 Exam Tip: When discussing advantages, mention efficiency, use for seedless varieties, and the benefit of producing genetically identical offspring (clones).

RBSE Class 12 Biology Chapter 1 Essay Type Questions

Question 1. Explain in detail Asexual reproduction in angiosperms.
Answer: Asexual reproduction in angiosperms, also called apomixis, is a process where new plants are formed without the normal fusion of gametes or fertilization, unlike sexual reproduction. This means only mitotic cell divisions are involved, resulting in offspring that are genetically identical clones of the parent plant. Asexual reproduction can be categorized based on the plant part involved: **(i) Natural Vegetative Propagation:** This occurs when a part of the parent plant detaches and grows into a new individual. * **By Stems:** Stems can be modified for reproduction. * **Tuber:** An underground stem tip (e.g., potato) with "eyes" (buds) that sprout new plants.
A-C, Vegetative propagation by stem: A. Bulb, B. Runner, C. Rhizome * **Rhizome:** A horizontal underground stem (e.g., ginger) with distinct nodes and internodes. * **Corm:** A condensed, vertical underground stem (e.g., Colocasia) where axillary buds form new plants. * **Bulb:** A very short stem with fleshy leaves and buds (e.g., onion) that grow to form an aerial shoot. * **Runners:** Creeping stems growing just above ground (e.g., doob grass) that root at nodes and form new plants when they break off.
Vegetative propagation by stem: A Tuber, B. Corm, C. Offset * **Offset:** Similar to a runner, but thicker, with a tuft of leaves at the apex (e.g., water hyacinth). * **By Roots:** Some roots are modified to help in reproduction (e.g., sweet potato, Asparagus, Dahlia). * **By Leaves:** Certain leaves develop buds along their edges (e.g., Bryophyllum) that grow into plantlets and form new plants upon detachment.
Vegetative propagation by leaves: Plantlets in A. Bryophyllum, B. Begonia * **By Reproductive Parts:** Special multicellular structures called bulbils, which are transformed floral buds, develop on an inflorescence (e.g., onion, Agave). These shed from the plant and grow into new plants.
A-B. Vegetative propagation by bulbils borne on inflorescence: A. Globba, B. Agave. **(ii) Artificial Vegetative Propagation:** These are human-devised methods used for cultivating economically important plants, ensuring desirable traits are maintained in genetically identical clones. Artificial methods of vegetative propagation include cuttings, grafting, layering and micropropagation. * **Cuttings:** Pieces of stem or root are taken from a plant and encouraged to root and grow into new individuals. Plant hormones like IAA are often used to promote rooting. * **Stem cuttings:** Common method where stems root to form new plants. * **Root cuttings:** Roots placed in moist soil sprout new roots and shoots (e.g., lemon, tamarind). * **Grafting:** Joining a scion (upper part with desired traits) from one plant onto a stock (rooted lower part) of another plant. * **Whip or Tongue Grafting:** Scion and stock of similar thickness are cut diagonally and fitted together. * **Wedge Grafting:** Scion and stock of similar thickness; a V-shaped cut is made in the stock, and a wedge-shaped scion is inserted. * **Crown Grafting:** Used when stock is much thicker than scion; scion branches are inserted into slits cut in the stock's bark. * **Bud Grafting:** A T-shaped cut is made in the stock, and a bud from the scion is inserted into it. * **Layering:** Inducing roots on a stem while it's still attached to the parent plant, then separating it. * **Mound Layering:** A low-growing branch is bent to the ground, part of it is covered with soil, and it roots before separation. * **Air Layering (Gootee):** A ring of bark is removed from a woody branch, which is then covered with moist material and wrapped to induce rooting before separation. * **Micropropagation:** This is a modern tissue culture technique used for rapidly producing disease-free plants or homozygous diploids.
In simple words: Asexual reproduction in plants makes new plants without seeds, and they are exact copies of the parent. This can happen naturally from stems (like potatoes or ginger), roots (like sweet potato), or leaves (like Bryophyllum). People also use artificial ways like cuttings (planting a piece of stem or root), grafting (joining two plant parts), layering (making a stem grow roots while still attached), and micropropagation (growing tiny plants in a lab).

🎯 Exam Tip: For a detailed explanation, break down asexual reproduction into natural and artificial methods. For each method, provide a brief description and a relevant plant example.

Micropropagation: A. Culture tube with tissue. B. Organised callus, Plantlets developed from callus.

Question 2. Describe different parts of the flower of angiosperm.
Answer: An angiosperm flower is actually a specialized shoot that grows only to a certain size. It sits on a stalk called the pedicel. At the top of the pedicel is a flat, wide part called the thalamus. On this thalamus, four distinct types of modified leaves are arranged in four circles, or whorls. These whorls are: * **Calyx:** The outermost whorl, made of sepals, which are usually green and protective. * **Corolla:** The whorl inside the calyx, made of petals, which are often brightly colored to attract pollinators. * **Androecium:** The male reproductive whorl, made of stamens (each with an anther and filament). * **Gynoecium:** The female reproductive whorl, made of carpels (each with an ovary, style, and stigma).
The calyx and corolla are known as **accessory whorls** because they support and protect the flower but are not directly involved in producing seeds. The androecium and gynoecium are called **essential (or necessary) whorls** because they contain the reproductive parts crucial for seed formation.
In simple words: A flower is like a special stem on a stalk (pedicel) with a base (thalamus). It has four main parts in circles: the green calyx, colorful corolla, male androecium, and female gynoecium. Calyx and corolla are helpers, while androecium and gynoecium are key for making new plants.

🎯 Exam Tip: When describing flower parts, name each whorl, describe its components (e.g., calyx-sepals), its function, and whether it's an accessory or essential whorl.

Question 3. Write a brief account of artificial methods of vegetative reproduction.
Answer: Artificial methods of vegetative reproduction are human-made techniques used to grow commercially important ornamental and fruit plants. These methods include: 1. **Cuttings:** This involves taking a piece of a plant, like a stem or root, and encouraging it to grow new roots and shoots. * **Stem cuttings:** Stems are planted, and they develop roots and buds. Rooting hormones (like IAA) can be used to help. * **Root cuttings:** Roots are placed in moist soil to sprout new roots and shoots, as seen in plants like lemon or tamarind. 2. **Grafting:** This is a popular gardening technique where a part of one plant (the scion, a branch with desired qualities) is joined to a rooted part of another plant (the stock). This helps create new varieties or improve plant vigor. * **Whip or Tongue Grafting:** Used for scions and stocks of similar thickness. Both are cut diagonally, then specially notched to fit tightly together before being sealed with wax. * **Wedge Grafting:** Also for scions and stocks of similar thickness. A V-shaped cut is made in the stock, and a matching wedge-shaped cut is made on the scion, which is then inserted firmly and sealed.
In simple words: Artificial plant growing methods help us quickly grow useful plants. These include **cuttings** (planting a piece of stem or root), and **grafting** (joining parts of two different plants, like a good branch onto a strong root system, using methods like whip or wedge grafting).

🎯 Exam Tip: Briefly list and describe the primary artificial methods (cuttings, grafting, layering, micropropagation) and give a simple explanation for each, focusing on their practical application.

Question 3. Write a brief account of artificial methods of vegetative reproduction.
Answer: These methods are developed by humans and are used to propagate commercially useful ornamental and fruit plants. The main methods of artificial propagation are:

(1) Cuttings: When cuttings from plants are placed in soil, they grow roots at the base and develop buds. Sometimes, roots are not easily produced, so cuttings are treated with IAA to help rooting. Root cuttings (like lemon and tamarind) can also sprout roots and shoots from moist soil.

(2) Grafting: This is a common horticulture method where two different plants are joined to create a new variety. A small branch with desired features (scion or graft) is inserted into a rooted plant (stock) of the same or allied species to form a union. The stock provides water and minerals, while the scion grows, keeping its qualities. This method is useful for commercial plants like rose, mango, apple, pear, guava, and citrus. Main methods include:
1. Whip or Tongue grafting: Here, both scion and stock of similar thickness are cut 5-8 cm long. A V-shaped cut is made in the stock, and a complementary cut in the scion. They are joined tightly and covered with grafting wax.
2. Wedge grafting: This method is used when the scion and stock have the same diameter. A V-shaped cut is made in the stock, and a wedge-shaped cut in the scion. The two parts are joined tightly and sealed with grafting wax.
3. Crown grafting: This method is used when the stock is much thicker than the scion. The stock's bark is cut 12-15 cm downwards. A small branch of the same species is cut and inserted into this slit in the bark, then tied firmly. The wound is covered with grafting wax.
4. Bud grafting: In this method, a T-shaped cut is made in the bark of the stock. A bud from a chosen plant is inserted into this T-shaped slot and properly bandaged. This allows several rose varieties to grow on one stock.

(3) Layering: In this method, roots are encouraged to grow on the stem while it is still connected to the parent plant. After roots form, this part is separated and grown as an independent plant. There are two common types:
1. Mound layering: A branch near the ground is bent down, and a 2.5-5.0 cm ring of bark is removed. This portion is pushed into soft, moist soil, keeping the branch tip above ground. After a few days or weeks, the covered part grows adventitious roots, and the branch is then detached.
2. Air layering or Gootee: This technique is used for trees with thick branches that cannot be easily bent. During early rains, a healthy, woody branch is selected and girdled (a 2.5-5 cm ring of bark is sliced off). The girdled part is covered with moist moss or cotton, then wrapped in a polythene bag or jute. This wrapped part is called Gootee. To keep the gootee wet, an earthen pot with a small hole can be hung above it to drip water, as shown in the diagram. Roots usually develop within 1-3 months, after which it is separated from the parent plant and planted.


(4) Micropropagation: This is a modern technique used to grow disease-free plants and homozygous diploids.
In simple words: Artificial methods of plant reproduction are ways humans help plants grow new individuals. These include cuttings (taking a piece of stem or root to grow a new plant), grafting (joining parts of two plants to grow as one), layering (making roots grow on a branch while it's still attached to the parent plant), and micropropagation (growing plants in a lab from very small pieces). These methods help keep good plant traits and grow many plants quickly.

🎯 Exam Tip: Remember the specific techniques for each artificial method (e.g., V-shaped cuts for grafting, girdling for air layering) and their suitable plant types.