RBSE Solutions Class 12 Biology Chapter 3 Pollination, Fertilization & Development of Endosperm and Embryo

RBSE Class 12 Biology Chapter 3 Multiple Choice Questions

Question 1. In which of the following, cleistogamous pollination is found?
(a) Viola
(b) Papaya
(c) Jamun (BlackBerry)
(d) Cassia
Answer: (a) Viola
In simple words: Cleistogamous flowers never open. They pollinate themselves inside the closed flower, and Viola is an example of a plant that does this.

🎯 Exam Tip: Remember key examples for different types of pollination and fertilization processes, as these are often tested.

Question 3. What develops after triple fusion?
(a) Embryo sac
(b) Embryo
(c) Endosperm
(d) Seed
Answer: (c) Endosperm
In simple words: When three specific nuclei join together in a plant's ovule, it forms the endosperm, which is like food storage for the developing plant embryo.

🎯 Exam Tip: Understand the sequence of events in double fertilization and what structures arise from each fusion event.

Question 4. Seed coats develop from -
(a) Integuments
(b) Nucellus
(c) Funicle
(d) Hilum
Answer: (a) Integuments
In simple words: The outer protective layers of the ovule, called integuments, transform into the tough outer covering of the seed after fertilization, protecting the embryo.

🎯 Exam Tip: Be able to identify the precursor structures in an ovule that develop into different parts of a mature seed.

Question 5. Who discovered double fertilization?
(a) Robert Hooke
(b) Strasburger
(c) Nawaschin
(d) Leeuwenhoek
Answer: (c) Nawaschin
In simple words: A scientist named Nawaschin was the first to find out about double fertilization, which is a special way plants reproduce.

🎯 Exam Tip: Knowing key discoveries and the scientists behind them can earn you easy marks in biology. Also, make sure to spell names correctly.

RBSE Class 12 Biology Chapter 3 Very Short Answer Questions

Question 2. Differentiate between homogamy and dichogamy.
Answer: In some plants, the male and female parts (stamens and carpels) of a flower become ready at the same time. This is called homogamy, which helps the flower pollinate itself. On the other hand, dichogamy is when these parts become ready at different times. This prevents self-pollination and encourages pollination from other flowers.
In simple words: Homogamy means a flower's male and female parts are ready together for self-pollination. Dichogamy means they mature at different times, stopping self-pollination.

🎯 Exam Tip: When asked to differentiate, clearly state the key difference for each term and provide an example if possible.

Question 3. Define incompatibility?
Answer: Incompatibility, also known as self-sterility, is when a pollen grain cannot grow on the stigma of the same flower or a flower from the same type of plant. This happens because the pollen and the pistil do not interact well. The reason can be due to physical features or how they function. This situation makes it necessary for cross-pollination to happen instead.
In simple words: Incompatibility means a plant's own pollen cannot make seeds on its own flower, forcing it to get pollen from another plant.

🎯 Exam Tip: When defining terms, use clear and concise language. Include the main cause and effect of the process.

Question 4. Name the scientist who first of all discovered fertilization in plants?
Answer: The process of fertilization in plants was first discovered by Strasburger in 1884.
In simple words: Strasburger was the first scientist to discover how fertilization works in plants.

🎯 Exam Tip: For historical facts, ensure you mention both the scientist's name and the year of discovery if available.

Question 5. Differentiate between epicotyl and hypocotyl.
Answer: The epicotyl is the part of the embryo's stem located above where the seed leaves (cotyledons) attach. In contrast, the hypocotyl is the part of the stem below the cotyledons, connecting to the root.
In simple words: The epicotyl is the stem part above the seed leaves, and the hypocotyl is the stem part below them.

🎯 Exam Tip: Visualize the structure of a seedling when differentiating between plant parts to easily recall their positions.

Question 7. Name two hormones which induce parthenocarpy.
Answer: Spraying auxins and gibberellins on the stigma can make some plants produce fruit without fertilization, a process called parthenocarpy.
In simple words: Auxins and gibberellins are two hormones that can make fruits grow without seeds.

🎯 Exam Tip: Focus on understanding the role of plant hormones in various processes, as they are a common topic in plant physiology.

Question 8. What does plumule forms at the time of seed germination?
Answer: After a seed germinates, the plumule grows to form the shoot system of the new plant, which includes the stem, leaves, and flowers.
In simple words: When a seed sprouts, the plumule becomes the plant's shoot, which is the part above the ground.

🎯 Exam Tip: Remember that the plumule forms the shoot, while the radicle forms the root system of the plant.

Question 9. From where does developing embryo gets nutrition?
Answer: During its development, the plant embryo gets its food and nutrients from the endosperm, which is a special tissue within the seed.
In simple words: The growing baby plant inside the seed gets its food from the endosperm.

🎯 Exam Tip: Understand the role of the endosperm as a nutritive tissue for the developing embryo. In some seeds, cotyledons also store food.

Question 10. Why pollen grains are conserved for a long time?
Answer: The wall of a pollen grain has a tough layer called sporopollenin. This substance makes it waterproof, resistant to decay by microbes, and very stiff. This hard outer shell helps the delicate cell inside survive for a long time.
In simple words: Pollen grains last long because their hard outer wall, made of sporopollenin, protects them from water, decay, and damage.

🎯 Exam Tip: Sporopollenin is a key term here. Highlight its properties (waterproof, resistant to decay, stiff) that contribute to pollen's longevity.

Question 11. Differentiate between albuminous and exalbuminous seeds.
Answer: In albuminous seeds, the endosperm tissue remains in the mature seed and is used as food during germination. The embryo in these seeds is usually very small. In contrast, exalbuminous seeds use up all their endosperm during embryo development, so the mature seed does not contain endosperm. In such seeds, the embryo is large, and food is stored in the cotyledons.
In simple words: Albuminous seeds keep their endosperm for food, while exalbuminous seeds use it all up during growth and store food in their large seed leaves (cotyledons).

🎯 Exam Tip: Focus on the presence or absence of endosperm in the mature seed as the primary differentiating factor, and relate it to where food is stored.

Question 13. Name the Scientist and the plant in which double fertilization was first observed.
Answer: Double fertilization was first studied by Nawaschin in 1898. It was first observed in the plant Fritillaria SPS.
In simple words: Nawaschin discovered double fertilization in 1898 while studying the Fritillaria plant.

🎯 Exam Tip: Remember both the scientist's name and the specific organism or plant species associated with a discovery when asked.

Question 14. Write peculiarities of pollen formed in wind-pollinated flowers.
Answer: Wind-pollinated flowers produce a large amount of pollen. This pollen is typically small, dry, light, and smooth, making it easy for the wind to carry them over long distances.
In simple words: Wind-pollinated flowers make lots of small, light, and dry pollen that the wind can easily blow far away.

🎯 Exam Tip: Think about how each characteristic of wind-pollinated pollen (quantity, size, weight, texture) helps in effective wind dispersal.

Question 15. Write the ploidy (n or 2n or 3n) nature of polar nuclei, primary endosperm nucleus, definitive nucleus synergids and nucellus.
Answer:
• Polar nuclei: \( n \)
• Primary endosperm nucleus: \( 3n \)
• Definitive nucleus: \( 2n \)
• Synergids: \( n \)
• Nucellus: \( 2n \)
In simple words: Ploidy tells us how many sets of chromosomes are in a cell. For these plant parts, polar nuclei and synergids are single sets (n), the definitive nucleus and nucellus are double sets (2n), and the primary endosperm nucleus is a triple set (3n).

🎯 Exam Tip: Memorize the ploidy levels of different structures in the angiosperm life cycle, as they are fundamental to understanding plant reproduction.

Question 16. Differentiate between pericarp and perisperm.
Answer: After pollination and fertilization, the ovules become seeds, and the ovary changes into the fruit. The wall of the ovary forms the fruit wall, which is called the pericarp. On the other hand, perisperm is what's left of the nucellus (nutritive tissue in the ovule) in the form of a thin, papery layer in some seeds, like black pepper.
In simple words: Pericarp is the fruit wall that comes from the ovary, while perisperm is a thin, papery leftover of the nucellus in some seeds.

🎯 Exam Tip: Clearly distinguish between structures derived from the ovary (pericarp) and those derived from the ovule itself (perisperm and seed). An example like black pepper is useful.

Question 2. What is meant by self sterility?
Answer: Self-sterility is also called incompatibility. It means that pollen cannot germinate on the stigma of the same flower or other flowers from the same plant type, so no seeds are formed. This happens due to a negative interaction between the pollen and the pistil, possibly because of physiological or morphological reasons. This forces the plant to rely on cross-pollination.
In simple words: Self-sterility means a plant's own pollen cannot create seeds on its own flower, making it depend on pollen from other plants for reproduction.

🎯 Exam Tip: When explaining self-sterility, remember to mention both its synonym (incompatibility) and the biological reason (negative pollen-pistil interaction) for it.

RBSE Class 12 Biology Chapter 3 Essay Type Questions

Question 3. With the help of well-labelled diagrams, Explain different types of endosperm development in angiosperms.
Answer: There are three main ways endosperms form in flowering plants:
1. Nuclear type: In this method, the primary endosperm nucleus divides many times without forming cell walls, creating many free nuclei. These nuclei then arrange around the edges of the embryo sac, forming a large empty space in the middle. Later, cell walls might form around the nuclei. This type is common in many flowering plant families. Coconut water is a good example of this liquid endosperm.
2. Cellular type: Here, the primary endosperm nucleus divides, and each division is immediately followed by the formation of a cell wall. This divides the embryo sac into several separate compartments. This type of endosperm formation is often seen in certain plant groups, such as Villarsia and Adoxa.
3. Global endosperm: This type is a mix between the nuclear and cellular types. The first division of the endosperm nucleus forms two unequal cells. The larger cell then undergoes free nuclear divisions, which are later followed by cell wall formation. The smaller cell usually divides only once or twice and acts as a small absorbing cell. This is seen in monocot plants like those in the order Helobiales.
In simple words: Endosperm, the food for plant embryos, forms in three ways: Nuclear (many free nuclei, like coconut water), Cellular (cell walls form with each division), and Global (a mix of both).

🎯 Exam Tip: When asked to explain different types, clearly define each type and provide a specific example if possible. Also, understand the key difference in cell wall formation for each type.