Question 1

Which of the following best describes the role of maturation promoting factor (MPF) in the regulation of the cell cycle?

Accepted Answer

MPF is a complex of cyclin and cyclin-dependent kinase (cdk) that triggers the cell's entry into mitosis by phosphorylating target proteins.

Question 2

A cell with 8 chromosomes undergoes mitosis. How many chromosomes and chromatids will each daughter cell have immediately after cytokinesis?

Accepted Answer

8 chromosomes and 8 chromatids

Question 3

During which phase of meiosis does crossing-over occur, and what is its significance?

Accepted Answer

Prophase I; it increases genetic variation by exchanging genetic material between homologous chromosomes.

Question 4

A genetic cross between two heterozygous individuals for a single gene (Aa x Aa) results in which expected phenotypic ratio?

Accepted Answer

$$3:1$$

Question 5

Which of the following scenarios best illustrates incomplete dominance?

Accepted Answer

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

Question 6

Which of the following best explains why dominant traits are not always the most common traits in a population?

Accepted Answer

Dominance refers to the expression of an allele in the heterozygote, not its frequency in the population.

Question 7

A pedigree shows that a trait appears in every generation and affects both males and females equally. Which inheritance pattern is most likely?

Accepted Answer

Autosomal dominant

Question 8

Which event distinguishes anaphase of mitosis from anaphase I of meiosis?

Accepted Answer

In mitosis, sister chromatids separate; in meiosis I, homologous chromosomes separate.

Question 9

A woman who is a carrier for an X-linked recessive disorder and a man who is unaffected have a son. What is the probability that their son will have the disorder?

Accepted Answer

$$0.5$$

Question 10

Which of the following best describes the process and purpose of apoptosis?

Accepted Answer

Programmed cell death involving DNA fragmentation, membrane blebbing, and removal by macrophages to eliminate damaged or unnecessary cells.

Question 11

Which of the following is a source of genetic variation unique to meiosis and not mitosis?

Accepted Answer

Independent assortment of homologous chromosomes during metaphase I.

Question 12

A cell fails to pass the G1 checkpoint due to DNA damage. Which of the following is a possible fate for this cell?

Accepted Answer

It may undergo apoptosis to prevent propagation of mutations.

Question 13

Which of the following best explains the difference between oogenesis and spermatogenesis in humans?

Accepted Answer

Oogenesis produces one viable egg and polar bodies, while spermatogenesis produces four viable sperm.

Question 14

Which of the following is a function of tumor suppressor genes in the cell cycle?

Accepted Answer

They halt the cell cycle at checkpoints to allow for DNA repair or trigger apoptosis if damage is irreparable.

Question 15

A dihybrid cross between two individuals heterozygous for both traits (AaBb x AaBb) produces which expected phenotypic ratio?

Accepted Answer

$$9:3:3:1$$

Question 16

Which of the following best describes the function of telomerase in eukaryotic cells?

Accepted Answer

It extends the telomeres at the ends of chromosomes to prevent loss of genetic material during DNA replication.

Question 17

A man with blood type AB and a woman with blood type O have children. Which blood types are possible for their children?

Accepted Answer

Type A or Type B

Question 18

Which of the following is an example of a pleiotropic gene effect?

Accepted Answer

A single gene mutation causes multiple symptoms, such as in sickle cell disease affecting blood cells, pain, and organ function.

Question 19

Which of the following mechanisms is responsible for correcting errors that occur during DNA replication?

Accepted Answer

DNA proofreading by DNA polymerase and mismatch repair enzymes.

Question 20

A cell is observed to have membrane blebbing, DNA fragmentation, and formation of apoptotic bodies. What is most likely occurring?

Accepted Answer

The cell is undergoing apoptosis.

Cell Division, Genetics, and Regulation: Study Guide for Biology 161

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