29. Which of the following events occurs in metaphase I of meiosis and contributes to genetic variation?
Answer: A
Independent assortment occurs in metaphase I of meiosis and contributes to genetic variation.
During metaphase I of meiosis, independent assortment refers to the random alignment of homologous chromosome pairs at the metaphase plate, which leads to diverse combinations of chromosomes in the resulting gametes.
A) Independent assortment
This option is correct because independent assortment directly describes the process that occurs during metaphase I, where homologous chromosomes align randomly. This randomness is a key mechanism that increases genetic variation in the gametes produced.
B) Reduction division
Reduction division refers to the overall process of meiosis where the chromosome number is halved, occurring during anaphase I and II rather than metaphase I. While it is an important aspect of meiosis, it does not specifically occur in metaphase I nor does it directly contribute to genetic variation.
C) Crossing over
Crossing over is the exchange of genetic material between homologous chromosomes that occurs during prophase I, not metaphase I. Although crossing over is a significant contributor to genetic variation, it does not take place during the metaphase I stage.
D) Homologous pairing
Homologous pairing occurs during prophase I when homologous chromosomes align closely together. While this is an essential step in meiosis, it does not happen during metaphase I and is not responsible for the genetic variation that independent assortment provides.
Conclusion
Independent assortment is the only process listed that occurs specifically during metaphase I and is a crucial mechanism for generating genetic diversity. Other options either occur at different stages of meiosis or do not contribute to genetic variation in the context of metaphase I. Hence, independent assortment stands out as the correct answer in this context.