Join thousands of students who trust us to help them ace their exams!Watch the first video
Multiple Choice
Which of the following events occurs during prophase I of meiosis?
A
Sister chromatids separate and move to opposite poles.
B
Chromosomes align individually along the metaphase plate.
C
The nuclear envelope reforms around chromosomes.
D
Homologous chromosomes pair and exchange genetic material through crossing over.
Verified step by step guidance
1
Understand the context of meiosis: Meiosis is a type of cell division that reduces the chromosome number by half, creating four haploid cells. It consists of two stages: meiosis I and meiosis II. Prophase I is a key phase in meiosis I.
Recognize the unique events of prophase I: Unlike mitosis, prophase I involves homologous chromosomes pairing up (synapsis) and exchanging genetic material through crossing over. This increases genetic diversity.
Clarify the incorrect options: Sister chromatids separating occurs during anaphase II of meiosis, not prophase I. Chromosomes aligning individually along the metaphase plate happens during metaphase II. The nuclear envelope reforms during telophase, not prophase I.
Focus on the correct event: During prophase I, homologous chromosomes pair up to form tetrads. Crossing over occurs at points called chiasmata, where segments of DNA are exchanged between non-sister chromatids.
Summarize the importance: Crossing over during prophase I is crucial for genetic recombination, which contributes to genetic variation in sexually reproducing organisms.