Class 12 Biology – Sexual Reproduction in Flowering Plants MCQs with Answers
Class 12 Biology often feels heavy because chapters like Sexual Reproduction in Flowering Plants include many steps (microsporogenesis, embryo sac, double fertilisation) and small terms that are easy to mix up. When exam pressure is high, practising MCQs helps you revise quickly and improve accuracy. This page gives you exam-style multiple choice questions with answers and short explanations, useful for CBSE school exams and early NEET-style practice. Focus on understanding the flow of events and the ploidy changes.
Core Content (MCQs)
Question 1
Assertion (A): The exine of a pollen grain is made up of sporopollenin. Reason (R): Sporopollenin provides resistance to pollen grains against adverse environmental conditions.
A. Both A and R are true and R is the correct explanation of A. B. Both A and R are true but R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true.
Answer: A
Explanation: Exine is composed of sporopollenin, which is highly resistant and protects pollen from drying and microbial attack.
Why the other options are wrong (quick check):
- B: R directly explains why sporopollenin is present.
- C/D: Both A and R are correct.
Question 2
What is the ploidy of the primary endosperm nucleus (PEN) formed after fertilisation in flowering plants?
A. Diploid (2n) B. Triploid (3n) C. Haploid (n) D. Tetraploid (4n)
Answer: B
Explanation: PEN forms by fusion of one male gamete (n) with two polar nuclei (n + n), so total becomes 3n.
Why the other options are wrong (quick check):
- A: That would happen if only two nuclei fused.
- C: PEN is not haploid.
- D: 4n is not formed in normal double fertilisation.
Question 3
Which statement is true regarding hybrid seeds and apomixis?
A. Apomixis causes segregation of hybrid characters in progeny. B. Hybrid seeds produced by apomixis maintain hybrid characters without segregation. C. Hybrid seeds do not require production every year if apomixis is absent. D. Apomixis increases the cost of hybrid seed production.
Answer: B
Explanation: Apomixis produces seeds without fertilisation, so the progeny remain genetically similar and hybrid traits are not lost by segregation.
Why the other options are wrong (quick check):
- A: Apomixis prevents segregation.
- C: Without apomixis, hybrid traits can segregate in the next generation.
- D: Apomixis can reduce repeated purchase/production needs.
Revision Tip: For ploidy questions, write n and 2n beside each structure (microspore, pollen, egg, polar nuclei) before answering.
Question 4
Assertion (A): Microspores develop into pollen grains after dissociation from the tetrad. Reason (R): The microspores remain attached as tetrads throughout pollen development.
A. Both A and R are true and R is the correct explanation of A. B. Both A and R are true but R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true.
Answer: C
Explanation: Microspores are formed as a tetrad after meiosis but later separate; each microspore develops into a pollen grain.
Why the other options are wrong (quick check):
- A/B: R is incorrect.
- D: A is correct.
Question 5
Which part of the embryo in dicot seeds terminates in the root tip covered by the root cap?
A. Epicotyl B. Hypocotyl C. Radicle D. Cotyledon
Answer: C
Explanation: Radicle is the embryonic root; it forms the primary root on germination and is protected by the root cap.
Why the other options are wrong (quick check):
- A: Epicotyl gives rise to the shoot.
- B: Hypocotyl is part of the embryonal axis below cotyledons.
- D: Cotyledons are seed leaves.
Question 6
Assertion (A): The mature embryo sac in angiosperms is 7-celled and 8-nucleate. Reason (R): The embryo sac contains two synergids, one egg cell, three antipodals, and a central cell with two polar nuclei.
A. Both A and R are true and R is the correct explanation of A. B. Both A and R are true but R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true.
Answer: A
Explanation: The central cell counts as one cell but contains two nuclei (polar nuclei), making total 8 nuclei in 7 cells.
Why the other options are wrong (quick check):
- B: R describes the exact cell/nuclei arrangement, so it explains A.
- C/D: Both A and R are correct.
Revision Tip: Memorise “2 synergids + 1 egg + 3 antipodals + 1 central cell (2 polar nuclei)” as a single line.
Question 7
Which part of the angiosperm flower represents the female gametophytic generation?
A. Pollen grain B. Embryo sac C. Microspore tetrad D. Anther
Answer: B
Explanation: Embryo sac is the female gametophyte (haploid) formed from the functional megaspore.
Why the other options are wrong (quick check):
- A: Pollen grain is the male gametophyte.
- C: Tetrad is an early stage in male gametophyte formation.
- D: Anther is a sporophytic structure.
Question 8
What is the correct sequence during microsporogenesis?
A. Sporogenous tissue → microspore mother cell → meiosis → microspore tetrad → pollen grain B. Microspore mother cell → sporogenous tissue → meiosis → pollen grain → microspore tetrad C. Sporogenous tissue → meiosis → microspore mother cell → microspore tetrad → pollen grain D. Microspore tetrad → sporogenous tissue → meiosis → microspore mother cell → pollen grain
Answer: A
Explanation: Sporogenous tissue differentiates into MMC/PMC, which undergoes meiosis to form a tetrad of microspores that mature into pollen.
Why the other options are wrong (quick check):
- B/C/D: They place meiosis or stages in the wrong order.
Question 9
Assertion (A): The zygote divides only after a certain amount of endosperm is formed. Reason (R): Endosperm provides nutrition to the developing embryo.
A. Both A and R are true and R is the correct explanation of A. B. Both A and R are true but R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true.
Answer: A
Explanation: Early endosperm development ensures a food reserve, so zygote division typically starts after endosperm begins forming.
Why the other options are wrong (quick check):
- B: R explains the reason for delayed division.
- C/D: Both A and R are correct.
Revision Tip: In many embryo questions, think “endosperm first, embryo next” for nutrition and support.
Question 10
Assertion (A): Tapetum cells are often multinucleate. Reason (R): Tapetal cells nourish developing pollen grains and have dense cytoplasm.
A. Both A and R are true and R is the correct explanation of A. B. Both A and R are true but R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true.
Answer: A
Explanation: Tapetum is metabolically very active to support pollen development, so it commonly becomes multinucleate with dense cytoplasm.
Why the other options are wrong (quick check):
- B: R supports why tapetum is highly active.
- C/D: Both A and R are correct.
You may also practice: Class 12 Biology – Sexual Reproduction in Flowering Plants MCQs (Difficulty-wise)
Continue practicing to strengthen your understanding and build consistency.