Question 1

A human skin cell in G1 phase contains 46 chromosomes. After the S phase of the cell cycle, how many chromatids and chromosomes will be present in the cell?

Accepted Answer

92 chromatids and 46 chromosomes

Question 2

Which of the following best explains why homologous chromosomes separate during Meiosis I but not during Meiosis II?

Accepted Answer

Homologous chromosomes pair and align during Meiosis I, allowing their separation, while Meiosis II separates sister chromatids.

Question 3

A woman who is heterozygous for a gene located on the X chromosome (X-linked) has children with a man who is not affected by the gene. What is the probability that their son will inherit the affected allele?

Accepted Answer

$$\frac{1}{2}$$

Question 4

Which of the following scenarios best illustrates the concept of incomplete dominance?

Accepted Answer

A cross between red-flowered and white-flowered snapdragons produces pink-flowered offspring.

Question 5

If a diploid organism has a chromosome number of $$2n = 8$$, how many different combinations of maternal and paternal chromosomes are possible in its gametes due to independent assortment (ignoring crossing over)?

Accepted Answer

$$2^4 = 16$

Question 6

A geneticist observes that two genes are often inherited together and rarely separated by recombination. What is the most likely explanation for this observation?

Accepted Answer

The genes are located close together on the same chromosome (gene linkage).

Question 7

Which of the following best describes the Law of Segregation as it applies to gamete formation?

Accepted Answer

Each gamete receives only one allele of each gene from the parent.

Question 8

A person with genotype $$I^A I^B$$ for the ABO blood group system has which blood type, and what inheritance pattern does this illustrate?

Accepted Answer

Type AB; codominance

Question 9

A cell undergoes a deletion mutation in one chromosome, removing a segment of DNA. Which of the following is a likely consequence?

Accepted Answer

Loss of genetic information, potentially resulting in genetic disorders

Question 10

Which of the following events during meiosis increases genetic variability in offspring?

Accepted Answer

Crossing over between homologous chromosomes

Question 11

A male with Klinefelter syndrome has a karyotype of $$47, XXY. $$Which chromosomal alteration does this represent?

Accepted Answer

Polysomy

Question 12

In a dihybrid cross between two heterozygous pea plants ($$RrYy 	imes RrYy$$), what is the expected phenotypic ratio among the offspring, assuming independent assortment?

Accepted Answer

$$9:3:3:1$$

Question 13

Which of the following best describes the difference between homologous chromosomes and sister chromatids?

Accepted Answer

Homologous chromosomes are similar but not identical chromosomes from each parent; sister chromatids are identical copies formed by DNA replication.

Question 14

A woman who is a carrier for a recessive X-linked disorder has children with a man who does not have the disorder. What is the probability that their daughter will have the disorder?

Accepted Answer

$$0$$

Question 15

Which of the following is an example of epistasis?

Accepted Answer

A gene for pigment deposition masks the expression of a gene for pigment color in Labrador retrievers.

Question 16

During which stage of the cell cycle does DNA replication occur?

Accepted Answer

S phase

Question 17

A cell with a diploid number of 10 undergoes mitosis. How many chromosomes will each daughter cell have after cytokinesis?

Accepted Answer

10

Question 18

Which of the following best explains why X-inactivation is important in female mammals?

Accepted Answer

It ensures dosage compensation so that females do not produce twice as many X-linked gene products as males.

Question 19

A chromosomal inversion occurs when:

Accepted Answer

A segment of a chromosome is reversed end to end.

Question 20

A plant with genotype $$AaBb is $$testcrossed with a plant with genotype $$aabb. If $$the two genes are unlinked, what proportion of the offspring are expected to have the genotype $$AaBb$$?

Accepted Answer

$$\frac{1}{4}$$

Cell Cycle, Meiosis, and Patterns of Inheritance: Study Notes

Study Guide - Practice Questions

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