2. all of the following are true of crossing over, except
crossing over occurs immediately after an egg is fertilized.
homologous chromosomes exchange genetic material.
crossing over results in unique combinations of alleles.
crossing over occurs during meiosis i.
crossing over occurs only in cells destined to become sperm or egg.

Drag each tile to the correct box. the body monitors the levels of oxygen in the blood to regulate breathing. isabel is running in a marathon and is near the finish line. she feels out of breath. how will her nervous system work to generate a reaction? arrange the tiles in chronological order. isabel's breathing rate increases. sensory receptors in the arteries detect low oxygen levels. the brain sends signals through motor neurons. sensory neurons generate an impulse. the central nervous system relays an impulse to certain brain regions.