NEETBotanyCell Cycle and Cell Division
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Recombination nodules appear during the pachytene stage of meiosis I. Reason (R): Crossing over occurs between the sister chromatids of the homologous chromosomes. In the light of the above statements, choose the most appropriate answer from the options given below:
Options
- A(A) is true but (R) is false.
- BBoth (A) and (R) are true and (R) is the correct explanation of (A).
- CBoth (A) and (R) are true but (R) is not the correct explanation of (A).
- DBoth (A) and (R) are false.
Correct answer
A. (A) is true but (R) is false.
Step-by-step solution
During the pachytene stage of prophase I in meiosis, recombination nodules appear, which mark the sites at which crossing over occurs. Therefore, the Assertion is true. Crossing over is the exchange of genetic material between two non-sister chromatids of the homologous chromosomes, not between sister chromatids. Therefore, the Reason is false. Answer: (A) is true but (R) is false.