Meiosis A) occurs in almost all cells in the human body. B) separates homologous chromosomes, but not chromatids. C) produces identical cells. D) does not require DNA replication like mitosis does. E) results in four haploid cells.
The correct answer and explanation is:
Correct Answer: E) results in four haploid cells.
Explanation (300 words):
Meiosis is a type of cell division that is essential for sexual reproduction. Unlike mitosis, which results in two identical diploid cells (cells with a full set of chromosomes), meiosis produces four non-identical haploid cells (cells with half the number of chromosomes). These haploid cells are gametes — sperm in males and eggs in females.
The primary purpose of meiosis is to reduce the chromosome number by half, ensuring that when fertilization occurs, the resulting zygote has the correct diploid number. In humans, diploid cells have 46 chromosomes (23 pairs), while haploid cells have only 23 chromosomes.
Meiosis occurs in two sequential stages: Meiosis I and Meiosis II. In Meiosis I, homologous chromosomes (pairs of chromosomes, one from each parent) are separated. This is a reductional division because it reduces the chromosome number from diploid to haploid. Meiosis I also includes a process called crossing over, where segments of DNA are exchanged between homologous chromosomes, increasing genetic diversity.
In Meiosis II, the sister chromatids of each chromosome are separated, similar to what occurs in mitosis. However, since the cells are already haploid after Meiosis I, the end result is four unique haploid cells.
Now let’s briefly address the incorrect options:
- A) is false because meiosis only occurs in germ cells (cells that produce gametes), not in almost all body cells.
- B) is partially true but incomplete — it separates homologous chromosomes in Meiosis I and chromatids in Meiosis II.
- C) is false because the cells produced by meiosis are genetically diverse, not identical.
- D) is false because DNA replication occurs before meiosis begins, during interphase, just like in mitosis.
Therefore, the best and fully correct answer is E) results in four haploid cells.