Question

what is a key difference between meiosis and mitosis? all of these are correct. crossing over only occurs in mitosis. synthesis of dna occurs. there is a difference in the number of times dna is divided.

Explanation:

• Crossing over occurs in meiosis (prophase I) not mitosis. So the option "Crossing over only occurs in mitosis" is wrong.
• DNA synthesis (in S - phase) occurs before both mitosis and meiosis. So the option "Synthesis of DNA occurs" is not a key difference.
• Mitosis has one round of DNA division (one cell division), while meiosis has two rounds of DNA division (two cell divisions).

Answer:

There is a difference in the number of times DNA is divided.