Question

multiple choice question
which of the following occurs during fertilization?
o mitosis is completed
o pronuclei unite to complete fertilization
o multiple sperm cells enter into the ovum cytoplasm
o the two polar bodies fuse to produce the zygote

Explanation:

• Mitosis is a type of cell division that occurs after fertilization (in embryonic development), not during fertilization.
• During fertilization, the sperm and egg pronuclei unite. The sperm enters the egg, and its nucleus (sperm pronucleus) fuses with the egg's nucleus (egg pronucleus) to form a diploid zygote, completing fertilization.
• Normally, only one sperm cell enters the ovum cytoplasm. There are mechanisms (like the cortical reaction) to prevent polyspermy (multiple sperm entry).
• Polar bodies are small cells produced during oogenesis and do not fuse to form a zygote. The zygote is formed from the fusion of sperm and egg pronuclei.

Answer:

Pronuclei unite to complete fertilization