Mastering Biology HW Chapter 13

A cell in prophase I has a diploid number (2n) of 36. At the end of meiosis II, how many sets of chromosomes will each gamete have?

1 set of chromosomes for a total of 18 chromosomes

In human gamete production there is an average of _____ crossover events per chromosome pair.

2-3

Which of these gametes contain one or more recombinant chromosomes?

B, C, F, and G

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

Mitosis can occur in both haploid and diploid cells, but meiosis cannot occur in haploid cells. Why not?

Meiosis produces daughter cells with half the number of chromosome sets of the parent cell; therefore, the parent cell cannot be haploid.

Which statement correctly describes the chromosomes in each daughter cell at the end of meiosis I?

The sister chromatids of each duplicated chromosome are no longer identical

Assume that an organism exists in which crossing over does not occur, but that all other processes associated with meiosis occur normally. Consider how the absence of crossing over would affect the outcome of meiosis. If crossing over did not occur, which of the following statements about meiosis would be true? Select all that apply.

There would be less genetic variation among gametes.

Homologous pairs of chromosomes are lined up independently of other such pairs during _____.

metaphase I

Crossing over, resulting in an increase in genetic variation, occurs between _____.

nonsister chromatids of homologous chromosomes