Question

which statement best describes what happens during the first division of meiosis?
a. the chromatids form two groups and are pulled to opposite sides of the cell.
b. four gametes join together and combine their chromosomes to form a diploid cell.
c. the cell membrane is pinched off to form two diploid cells with equal numbers of chromosomes.
d. the chromosomes are grouped into tetrads and then pulled apart so that each daughter cell receives one homologous chromosome from each tetrad.

Explanation:

• Option A: Chromatids are pulled apart in meiosis II, not meiosis I.
• Option B: Gametes are formed at the end of meiosis II, and they combine during fertilization, not during meiosis I.
• Option C: The cell membrane pinching off to form two cells occurs at cytokinesis (after nuclear division). In meiosis I, the result is two haploid cells (not diploid as diploid has \(2n\) chromosomes, and after meiosis I, the chromosome number is reduced to \(n\)).
• Option D: In meiosis I, homologous chromosomes pair up to form tetrads. Then, homologous chromosomes (one from each tetrad) are pulled to opposite poles of the cell so that each daughter cell gets one homologous chromosome from each tetrad. This is the key event of meiosis I which reduces the chromosome number from diploid (\(2n\)) to haploid (\(n\)).

Answer:

D. The chromosomes are grouped into tetrads and then pulled apart so that each daughter cell receives one homologous chromosome from each tetrad.