Question 1

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

Accepted Answer

Homologous chromosomes are inherited from each parent and may contain different alleles, while sister chromatids are identical copies formed during DNA replication.

Question 2

During which phase of the cell cycle does DNA replication occur, and what is the ploidy of the cell immediately after this phase?

Accepted Answer

DNA replication occurs during the S phase, and the cell remains diploid with duplicated chromosomes.

Question 3

Which of the following events occurs during prophase I of meiosis but not during mitosis?

Accepted Answer

Homologous chromosomes pair up and crossing over occurs.

Question 4

A plant with genotype $$YyRr ($$where Y = yellow, y = green, R = round, r = wrinkled) is self-crossed. According to Mendel’s Law of Independent Assortment, what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

$$9:3:3:1$$

Question 5

Which of the following best explains why sex-linked recessive diseases are more common in human males than females?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will result in the disease.

Question 6

A woman who is heterozygous for a sex-linked trait (X-linked recessive) and a man who does not have the trait have a child. What is the probability that their son will express the trait?

Accepted Answer

$$0.5$$

Question 7

Which of the following scenarios is an example of pleiotropy?

Accepted Answer

A single gene affects both the color of a flower and the shape of its leaves.

Question 8

If a cell fails to pass the G1 checkpoint, what is the most likely outcome?

Accepted Answer

The cell will enter the G0 phase and stop dividing.

Question 9

Which of the following best describes the difference between complete dominance, incomplete dominance, and codominance?

Accepted Answer

In complete dominance, only the dominant allele is expressed; in incomplete dominance, the heterozygote shows a blend; in codominance, both alleles are fully expressed.

Question 10

A geneticist observes a pedigree where a trait appears in every generation and affected fathers pass the trait to all their daughters but none of their sons. What is the most likely mode of inheritance?

Accepted Answer

X-linked dominant

Question 11

Which of the following events during meiosis increases genetic variation in sexually reproducing organisms?

Accepted Answer

Crossing over between homologous chromosomes during prophase I

Question 12

A cell with 24 chromosomes undergoes mitosis. How many chromosomes will each daughter cell have after cytokinesis?

Accepted Answer

24

Question 13

Which of the following best explains how nondisjunction during meiosis can lead to aneuploidy?

Accepted Answer

Homologous chromosomes or sister chromatids fail to separate, resulting in gametes with abnormal chromosome numbers.

Question 14

Which of the following is an example of epistasis?

Accepted Answer

One gene masks the expression of another gene, such as a gene for pigment deposition affecting coat color in mice.

Question 15

A couple are both carriers for cystic fibrosis, an autosomal recessive disorder. What is the probability that their child will have cystic fibrosis?

Accepted Answer

$$0.25$$

Question 16

Which of the following best describes the difference between autosomes and sex chromosomes?

Accepted Answer

Autosomes are chromosomes not involved in determining sex, while sex chromosomes determine an individual's gender.

Question 17

Which of the following is a real-world example of polygenic inheritance?

Accepted Answer

Human skin color, which is influenced by multiple genes.

Question 18

Which of the following best explains why lethal dominant genes are much rarer than lethal recessive genes in populations?

Accepted Answer

Lethal dominant alleles are usually eliminated from the population because affected individuals often die before reproducing.

Question 19

Which of the following best describes the process of binary fission in bacteria?

Accepted Answer

The bacterial chromosome replicates, and the cell divides into two genetically identical daughter cells.

Question 20

A man with blood type AB and a woman with blood type O have children. What are the possible blood types of their children?

Accepted Answer

A or B

Comprehensive Study Guidance for Cell Division, Genetics, and Chromosomal Inheritance

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