Insects that consume pollen or nectar without bringing about pollination are called:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Pollen robbers
Explanation: Many insects may consume pollen or the nectar without bringing about pollination. Such floral visitors are referred to as pollen/nectar robbers.
Consider the following statements regarding double fertilisation:
1. Syngamy involves the fusion of one male gamete with the egg cell.
2. Triple fusion results in the formation of a diploid Primary Endosperm Nucleus (PEN).
3. The central cell becomes the Primary Endosperm Cell (PEC) after triple fusion.
4. Double fertilisation is an event unique to flowering plants.
Which of the above statements are correct?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: 1, 3 and 4
Explanation: Statement 1 is correct: Syngamy is the fusion of a male gamete with the nucleus of the egg cell.
Statement 2 is incorrect: Triple fusion involves three haploid nuclei, resulting in a triploid (3n) PEN, not diploid.
Statement 3 is correct: The central cell becomes the PEC after fusion and develops into endosperm.
Statement 4 is correct: Double fertilisation is unique to angiosperms.
Consider the following statements about endosperm development:
1. Endosperm development always follows embryo development.
2. The PEN undergoes successive nuclear divisions to form free-nuclear endosperm.
3. Coconut water represents cellular endosperm.
4. The white kernel of coconut represents cellular endosperm.
Which of the above statements are correct?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: 2 and 4
Explanation: Statement 1 is incorrect: Endosperm development precedes embryo development to provide nutrition.
Statement 2 is correct: The most common type is free-nuclear endosperm formed by nuclear divisions.
Statement 3 is incorrect: Coconut water is free-nuclear endosperm.
Statement 4 is correct: The surrounding white kernel is the cellular endosperm.
Consider the following statements regarding seeds:
1. Non-albuminous seeds retain a part of the endosperm.
2. Pea and groundnut are examples of non-albuminous seeds.
3. Albuminous seeds completely consume endosperm during embryo development.
4. Castor and maize are examples of albuminous seeds.
Which of the above statements are correct?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: 2 and 4
Explanation: Statement 1 is incorrect: Non-albuminous seeds have no residual endosperm.
Statement 2 is correct: Pea and groundnut consume endosperm completely.
Statement 3 is incorrect: Albuminous seeds retain a part of the endosperm.
Statement 4 is correct: Castor, wheat, maize, and barley are albuminous.
Consider the following statements about the embryo:
1. The zygote divides only after a certain amount of endosperm is formed.
2. In dicots, the epicotyl terminates with the root tip.
3. The cylindrical portion below the cotyledons is the hypocotyl.
4. The hypocotyl terminates in the radicle.
Which of the above statements are correct?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: 1, 3 and 4
Explanation: Statement 1 is correct: This is an adaptation to provide assured nutrition.
Statement 2 is incorrect: The epicotyl terminates with the plumule (stem tip), not the root tip.
Statement 3 is correct: The portion below the level of cotyledons is the hypocotyl.
Statement 4 is correct: The hypocotyl terminates at its lower end in the radicle.
Consider the following statements regarding monocot embryos:
1. They possess only one cotyledon called the scutellum.
2. The scutellum is situated centrally in the embryonal axis.
3. The coleorrhiza encloses the shoot apex.
4. The coleoptile is a hollow foliar structure enclosing leaf primordia.
Which of the above statements are correct?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: 1 and 4
Explanation: Statement 1 is correct: The single cotyledon in grass family is the scutellum.
Statement 2 is incorrect: The scutellum is situated towards one side (lateral), not centrally.
Statement 3 is incorrect: The coleorrhiza encloses the radicle and root cap.
Statement 4 is correct: The coleoptile encloses the shoot apex and leaf primordia.
Consider the following statements about seed structure:
1. The micropyle remains as a small pore in the seed coat.
2. Integuments harden to form the pericarp.
3. Perisperm is the residual persistent nucellus.
4. Black pepper and beet contain perisperm.
Which of the above statements are correct?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: 1, 3 and 4
Explanation: Statement 1 is correct: The micropyle facilitates entry of oxygen and water.
Statement 2 is incorrect: Integuments harden to form the seed coat, not pericarp (which is fruit wall).
Statement 3 is correct: Residual nucellus is called perisperm.
Statement 4 is correct: Black pepper and beet are examples of perispermic seeds.
Consider the following statements regarding fruits:
1. Fruits that develop only from the ovary are called true fruits.
2. In false fruits, the thalamus contributes to fruit formation.
3. Apple and strawberry are examples of true fruits.
4. Parthenocarpic fruits develop without fertilisation.
Which of the above statements are correct?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: 1, 2 and 4
Explanation: Statement 1 is correct: True fruits develop only from the ovary.
Statement 2 is correct: False fruits involve the thalamus.
Statement 3 is incorrect: Apple and strawberry are false fruits.
Statement 4 is correct: Parthenocarpic fruits (e.g., banana) develop without fertilisation.
Consider the following statements about seed viability and dormancy:
1. Mature seeds have a water content of about 50 per cent by mass.
2. The embryo in a dormant seed enters a state of inactivity.
3. Lupinus arcticus seeds remained viable for about 10,000 years.
4. A 2000-year-old viable Date Palm seed was discovered at King Herod’s palace.
Which of the above statements are correct?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: 2, 3 and 4
Explanation: Statement 1 is incorrect: Mature seeds are dry with 10-15 per cent moisture.
Statement 2 is correct: Metabolic activity slows down in dormancy.
Statement 3 is correct: Lupine seeds from Arctic Tundra germinated after 10,000 years.
Statement 4 is correct: Phoenix dactylifera seed was viable for 2000 years.
Consider the following statements regarding apomixis:
1. Apomixis is a form of asexual reproduction that mimics sexual reproduction.
2. It involves the production of seeds without fertilisation.
3. It is commonly observed in species of Asteraceae and grasses.
4. Apomictic embryos are genetically different from the parent plant.
Which of the above statements are correct?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: A
Answer: 1, 2 and 3
Explanation: Statement 1 is correct: It mimics sexual reproduction but is asexual.
Statement 2 is correct: Seeds are formed without fertilisation.
Statement 3 is correct: Asteraceae and grasses are common examples.
Statement 4 is incorrect: Apomictic embryos are clones and genetically identical to the parent.