Test Bank for Genetics, A Conceptual Approach, Update Seventh Edition by Benjamin A. Pierce 17. Pea plants have seven different types of chromosomes. A chromosome with a centromere at
the very end is called
a. submetacentric.
b. metacentric.
c. acrocentric.
d. acentric.
e. telocentric.
Answer: e
Section 2.2
Comprehension
18. A dividing eukaryotic cell is treated with a drug that inhibits the molecular motors associated
with kinetochores. At which cell cycle stage would it stop?
a. G1
b. S
c. G2
d. M (metaphase)
e. M (telophase)
Answer: d
Section 2.2
Application
19. Pea plants have seven different types of chromosomes. The nucleus of a megaspore in a pea
ovary would contain how many chromosomes?
a. 3 ½
b. 7
c. 14
d. 21
e. 30
Answer: b
Section 2.3
Comprehension (2) Crossing over. In meiosis I—prophase—portions of homologous chromosomes exchange,
changing combinations of alleles of genes on a single chromosome, so not even sister
chromatids are identical after crossing over. Each gamete has only one copy of each
homolog, and each homolog now has a unique combination of alleles.
Section 2.3
Comprehension
46. List two differences and two similarities between mitosis and meiosis.
Answer:
Differences:
(1) Mitosis occurs in somatic (nonsex) cells; meiosis occurs in sex cells to produce gametes.
(2) Meiosis involves chromosome pairing (of homologous chromosomes); mitosis does not.
(3) Mitosis produces nonsex cells; meiosis produces gametes.
(4) Mitosis produces cells of the same ploidy; meiosis produces haploid cells from diploid
cells.
(5) Meiosis has two consecutive divisions; mitosis has one.
(6) Mitosis produces two daughter cells; meiosis produces four daughter cells.
(7) Mitosis produces identical daughter cells; meiosis produces four different daughter cells.
Similarities:
(1) Both involve the separation of replicated chromosomes during cell division.
(2) Both are processes to ensure that daughter cells in cell division receive a complete set of
chromosomes.
(3) DNA replication must occur first.
(4) Cytokinesis usually occurs at the end of each.
Section 2.2-2.3
Application
47. Describe the difference between homologous chromosomes and sister chromatids.
Answer: Homologous chromosomes can have different alleles. Sister chromatids are
duplicates and (except for errors in replication) are identical in sequence.
Section 2.3
Application
48. Describe the difference between meiosis I and meiosis II.
Answer: Homologs pair and segregate in meiosis I. Sister chromatids are paired and
segregate in meiosis II. Crossing over occurs in meiosis I but not in meiosis II.
Section 2.3
Application
49. Describe the difference between the sporophyte and gametophyte.
Answer: The sporophyte is the diploid phase of a plant life cycle. The gametophyte is the
haploid stage.