Question

what do mitosis and meiosis have in common? all of these are correct. dna divides once in both processes. crossing over occurs. synthesis of dna occurs.

Explanation:

• DNA division: In mitosis, DNA divides once. In meiosis, DNA also divides once (in the S - phase before meiosis I).
• Crossing - over: Crossing - over occurs in meiosis (prophase I) but not in mitosis.
• DNA synthesis: Both mitosis and meiosis are preceded by a S - phase (synthesis phase) in the cell cycle where DNA is replicated.

Since the option "All of these are correct" is incorrect (because crossing - over does not occur in mitosis), we need to check each option:

• DNA divides once in both processes: Correct as explained above.
• Crossing over occurs: Incorrect (only in meiosis).
• Synthesis of DNA occurs: Correct (both have a pre - division S - phase).

Answer:

Synthesis of DNA occurs.