Question

Crossing-over occurs in meiosis I and meiosis II
- ture
-false

Answer 1

Crossing-over is a process that occurs during prophase I of meiosis I, contributing to genetic diversity by shuffling alleles between non-sister chromatids of homologous chromosomes. It does not occur in meiosis II.

Step-by-step explanation:

1. Crossing-over occurs during prophase I of meiosis I and not during meiosis II. It is a critical process involving the exchange of genetic material between non-sister chromatids of homologous chromosomes, resulting in new combinations of genes on each chromosome. During prophase I, these homologous chromosomes pair up in a formation known as a tetrad, and the chromatids come into close proximity allowing for crossover events. This recombination contributes to genetic diversity by shuffling alleles between chromosomes.
2. Crossing-over occurs in meiosis I during prophase I, not meiosis II. It is a mechanism that generates genetic variation in gametes.
3. The process of crossing-over is exclusive to meiosis I where homologous chromosomes line up in pairs during prophase I. This event is absent in meiosis II. The close alignment of homologous chromosomes allows for precise breaks and exchanges of DNA segments between non-sister chromatids, forming recombinant chromatids. Such genetic recombination shuffles alleles from the maternal and paternal chromosomes, thus increasing the genetic variation in offspring. This variation is fundamental to the principles of heredity and evolution, ensuring that each gamete—and ultimately each offspring—carries a unique set of genetic instructions, different from both parents and their siblings. Additionally, random assortment during metaphase I further contributes to the genetic uniqueness of the gametes produced.