Question

which best explains what happens during crossing over?
the chromosomes have electrical connections that allow them to line up randomly.
paired chromosomes overlap and portions of dna switch between chromosome.
genetic material is switched because the chromosomes line up independently.
chromosomes line up randomly and cross genetic information between unpaired chromosomes.

Explanation:

Crossing over occurs during meiosis when homologous (paired) chromosomes overlap, and segments of DNA are exchanged between them. Let's analyze each option:

• Option 1: Chromosomes don't have "electrical connections" for lining up randomly; this is incorrect.
• Option 2: This describes independent assortment (chromosomes lining up independently), not crossing over.
• Option 3: Paired chromosomes (homologous) overlapping and DNA segments switching between them accurately describes crossing over.
• Option 4: Crossing over involves paired (homologous) chromosomes, not unpaired ones, so this is incorrect.

Answer:

1. Paired chromosomes overlap and portions of DNA switch between chromosome.