Understanding Crossing Over in Meiosis

Crossing over occurs during prophase I of meiosis when homologous chromosomes align. Non-sister chromatids break at identical sites and exchange segments, which are sealed by enzymes. This process creates new allele combinations, enhancing genetic variability.

During which phase of meiosis does crossing over occur?

• Metaphase I

• Anaphase I

• Telophase I

• Prophase I

What happens to non-sister chromatids during crossing over?

• They break and exchange segments

• They disappear

• They duplicate

• They fuse together

Which enzymes are involved in sealing the exchanged segments of chromatids?

• Polymerases

• Helicases

• Topoisomerases

• Ligases

What is the result of crossing over in terms of alleles?

• Alleles are duplicated

• Alleles are deleted

• New combinations of alleles are formed

• Old combinations of alleles are preserved

How does crossing over affect genetic variability?

• It decreases genetic variability

• It has no effect on genetic variability

• It increases genetic variability

• It stabilizes genetic variability