Question

meiosis (2 of 3): the mechanism (bioflix tutorial)
3 parts | 0 of 1 point
part c (3 of 3) - changes in ploidy and dna content during meiosis
3 tries left
the parent cell that enters meiosis is diploid, whereas the four daughter cells that result are haploid.
which statement correctly describes how cellular dna content and ploidy levels change during meiosis i and meiosis ii?
dna content is halved only in meiosis i. ploidy level changes from diploid to haploid in meiosis i, and remains haploid in meiosis ii.
dna content is halved in both meiosis i and meiosis ii. ploidy level changes from diploid to haploid in meiosis i, and remains haploid in meiosis ii.
dna content is halved only in meiosis i. ploidy level changes from diploid to haploid only in meiosis ii.
dna content is halved in both meiosis i and meiosis ii. ploidy level changes from diploid to haploid only in meiosis ii.
dna content is halved only in meiosis ii. ploidy level changes from diploid to haploid in meiosis i, and remains haploid in meiosis ii.

Explanation:

• Meiosis I:
• DNA content: DNA is replicated before meiosis I (in S - phase). In meiosis I, homologous chromosomes separate. Each daughter cell after meiosis I gets half of the DNA content of the parent cell (because homologous chromosomes, each with two sister chromatids, are separated).
• Ploidy level: The parent cell is diploid (\(2n\)). After meiosis I, since homologous chromosomes are separated, the daughter cells are haploid (\(n\)).
• Meiosis II:
• DNA content: In meiosis II, sister chromatids separate. Each of the two daughter cells from meiosis I divides again. So the DNA content is halved again (because sister chromatids, which contain replicated DNA, are separated).
• Ploidy level: The cells entering meiosis II are haploid. Since sister chromatids (which do not change the ploidy level, as they are just copies of the same set of chromosomes in a haploid cell) are separated, the ploidy level remains haploid throughout meiosis II.

Answer:

DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II.