NEETBotanySexual Reproduction in Flowering Plants
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): A typical mature angiosperm embryo sac is 8-celled and 7-nucleate. Reason (R): During megagametogenesis, the functional megaspore undergoes sequential free-nuclear mitotic divisions, and cell walls are laid down later, enclosing two polar nuclei within a single large central cell. In the light of t
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
D. (A) is not correct but (R) is correct
Step-by-step solution
Assertion (A) is incorrect because a typical mature angiosperm embryo sac (Polygonum type) is 7-celled and 8-nucleate, not 8-celled and 7-nucleate. Reason (R) is correct. The functional megaspore undergoes three sequential free-nuclear mitotic divisions to form 8 nuclei. Cell wall formation occurs only after the 8-nucleate stage. Six of the eight nuclei are surrounded by cell walls and organised into cells (three in the egg apparatus and three antipodals), while the remaining two polar nuclei are situated in the si