A reduction in the number of chromosomes per cell occurs
a. During meiosis I
b. During meiosis II
c. During mitosis
d. During the S phase of interphase
Page 451 states that the answer is a.
I thought that the number of chromosomes at the end of meiosis I per cell equals the number of chromosomes in the parent cell (although sister chromatids remain attached), whereas the number of chromosomes at the end of meiosis II per cell equals half the number of chromosomes of the parent cell. If so, isn't the answer b?
It is the other way around. Meiosis I (or reductional division) splits chromosome pairs so each cell gets half of the chromosomes of the parent. Meiosis II (or equational division) splits double-chromatid chromosomes (making two single-chromatid chromosomes), so cells retain the number of chromosomes, like in mitosis.
If more clarification needed:
before the S phase: 23 pairs of chromosomes, 46 single-chromatid
before the meiosis I: 23 pairs of chromosomes, 46
before the meiosis II: 23
double-chromatid chromosomes without their homologous other
meiosis II: 23 single-chromatid chromosomes without their homologous