Question

How many chromosomes are found in primary spermatocytes and secondary oocytes of a human being?

Hint:

Check whether meiosis I has already happened for each named cell.

Answer 1

Step 1: Recall the human chromosome number and meiosis.
A normal human body cell has 46 chromosomes (23 pairs, diploid, 2n). Gamete-forming cells go through meiosis, which happens in two divisions, meiosis I and meiosis II, and only the second division actually splits the chromosome number in half.

Step 2: Place the primary spermatocyte in this timeline.
A primary spermatocyte is the cell just before it enters meiosis I; it has not yet divided, so it still carries the full diploid number.

Step 3: Place the secondary oocyte in this timeline.
A secondary oocyte is formed right after meiosis I is complete (the first meiotic division has already separated homologous chromosomes), so its chromosome number has already been halved to the haploid number.

Final Answer:
A primary spermatocyte has 46 chromosomes (diploid); a secondary oocyte has 23 chromosomes (haploid).