Answers to Review Questions - Chapter 10
1. What are the informational units on chromosomes called? Of what do these
informational units consist?
The informational units are the genes. The genes consist of specific nucleotide
sequences with the DNA that code for a particular product.
2. What are the stages of the cell cycle? During which stage does DNA replicate?
The cell cycle is composed of interphase (G1 phase, S phase, and G2 phases) and
the M phase (mitosis and cytokinesis). The genetic material is duplicated during
interphase (the S phase, specifically).
3. What are sister chromatids?
Sister chromatids are the duplicated chromosomes, resulting from DNA
replication, which are held together bythe centromere. After metaphase, when
they separate, they are then called chromosomes.
4. Assume an animal has a chromosome number of 10.
a. How many chromosomes would it have in a typical body cell, such as a
skin cell, during G1?
10 chromosomes (or 5 homologous pairs…)
b. How many sister chromatids would be in that cell during prophase of
mitosis?
20 sister chromatids due to DNA replication
c. If the same animal contained a stem cell undergoing division to produce
gametes - how many tetrads would form in prophase I of meiosis?
5 tetrads - one for each set of homologous chromosomes
5. Are homologous chromosomes present in a diploid cell? Are they present in a
haploid cell?
Yes, they are present in a diploid cell. They are not present in a haploid cell, as
the chromosomal content contains only one representative of each chromosome.
6. How does the outcome of meosis differ from the outcome of mitosis?
The outcome of meiosis is 4 genetically different haploid cells. The outcome of
mitosis is two genetically identical diploid cells.
7. Can haploid cells divide by mitosis? By meiosis?
Haploid cells generally do NOT divide by mitosis or meiosis. Technically, a
haploid cell could undergo division through mitosis, but this is not common.