Question

During which phase of meiosis does crossing over of chromosomes occur?

Answer 1

Prophase 1

Step-by-step explanation:

The main consequence of meiosis, no doubt, is the emergence of diversity among individuals that are produced in the sexual reproduction of the species.

The relationship between meiosis and variability is mainly based on the occurrence of crossing-over, which is a genetic phenomenon that occurs during Prophase 1.

Crossing over is a phenomenon involving homologous chromatids. It consists of the breaking of these chromatids at certain points, followed by an exchange of corresponding pieces between them.

Exchanges cause new gene sequences to appear along the chromosomes. Thus, if on a chromosome there are several genes combined in a certain sequence, after the occurrence of crossing the combination may no longer be the same.

Answer 2

-During pachytene stage of prophase I.

Step-by-step explanation:

Crossing over can be defined as the process of exchange of genetic material of a cell between two homologous, non-sister chromatids. It results in formation of recombinant chromosomes and causes variations in offspring.

Crossing over takes place during phachytene stage of prophase I of meiosis, during which homologous chromosomes come close by synapis and exchange the genetic material.

Thus, the correct answer is 'pachytene stage of prophase I.'