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Multiple Choice
Which of the following events occurs during Meiosis I but not during Mitosis?
A
Sister chromatids separate
B
The nuclear envelope reforms around chromosomes
C
Homologous chromosomes pair and undergo crossing over
D
Chromosomes align individually at the metaphase plate
Verified step by step guidance
1
Understand the key difference between Meiosis I and Mitosis: Meiosis I involves the separation of homologous chromosomes, while Mitosis involves the separation of sister chromatids.
Recall that homologous chromosomes are pairs of chromosomes (one from each parent) that are similar in size, shape, and genetic content. These pairs do not interact in Mitosis but do in Meiosis I.
Learn about crossing over: During Prophase I of Meiosis I, homologous chromosomes pair up in a process called synapsis, forming structures called tetrads. Crossing over occurs here, where segments of genetic material are exchanged between non-sister chromatids, increasing genetic diversity.
Compare metaphase alignment: In Meiosis I, homologous chromosome pairs align together at the metaphase plate, whereas in Mitosis, individual chromosomes align at the metaphase plate.
Conclude that the event 'Homologous chromosomes pair and undergo crossing over' is unique to Meiosis I and does not occur during Mitosis.