Question 1

Which of the following best explains why sexual reproduction provides an evolutionary advantage over asexual reproduction?

Accepted Answer

Sexual reproduction increases genetic variation, allowing populations to adapt more rapidly to changing environments.

Question 2

During which phase of the cell cycle does DNA replication occur, and what is the result of this process?

Accepted Answer

DNA replication occurs during the S phase of interphase, resulting in each chromosome consisting of two sister chromatids.

Question 3

A human somatic cell contains 46 chromosomes. How many chromosomes would you expect to find in a human gamete?

Accepted Answer

$$\displaystyle \frac{46}{2} = 23$$

Question 4

Which of the following statements correctly distinguishes between sister chromatids and homologous chromosomes?

Accepted Answer

Sister chromatids are identical copies of a chromosome joined at the centromere, while homologous chromosomes are similar but not identical chromosomes inherited from each parent.

Question 5

During which stage of mitosis do the spindle fibers attach to kinetochores and align chromosomes at the cell's equator?

Accepted Answer

Metaphase

Question 6

Which enzyme is responsible for unwinding the DNA double helix during DNA replication?

Accepted Answer

Helicase

Question 7

A woman with blood type AB and a man with blood type O have a child. Which of the following blood types could their child have?

Accepted Answer

A or B

Question 8

Which of the following best describes the difference between the leading and lagging strands during DNA replication?

Accepted Answer

The leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized discontinuously as Okazaki fragments.

Question 9

If a cell with a diploid number of $$2n = 8$$ undergoes meiosis, how many chromosomes will each resulting gamete contain?

Accepted Answer

$$\displaystyle \frac{8}{2} = 4$$

Question 10

Which of the following is a property of cancer cells that distinguishes them from normal cells?

Accepted Answer

Cancer cells can divide uncontrollably and often lose the ability to respond to regulatory signals.

Question 11

A man with genotype $$X^A Y$$ and a woman with genotype $$X^A X^a$$ have a son. What is the probability that their son will have the X-linked recessive trait?

Accepted Answer

$$\displaystyle 0.5$$

Question 12

Which of the following best describes the law of segregation as concluded by Mendel?

Accepted Answer

Each individual has two alleles for each gene, and these alleles separate during gamete formation so that each gamete receives only one allele.

Question 13

Which of the following bonds holds the two strands of DNA together, and why is this important for DNA replication?

Accepted Answer

Hydrogen bonds; they are weak enough to be broken during replication, allowing the strands to separate.

Question 14

A pedigree shows a trait that appears in every generation and affects both males and females equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 15

Which of the following enzymes is responsible for joining Okazaki fragments on the lagging strand during DNA replication?

Accepted Answer

DNA ligase

Question 16

A plant with genotype $$Rr ($$where $$R is $$dominant and $$r is $$recessive) is crossed with a plant with genotype $$rr. $$What is the expected phenotypic ratio of the offspring?

Accepted Answer

$$\displaystyle 1:1 ($$one dominant phenotype : one recessive phenotype)

Question 17

Which of the following best describes the role of actin during cytokinesis in animal cells?

Accepted Answer

Actin filaments form a contractile ring that pinches the cell membrane to separate the two daughter cells.

Question 18

Which of the following is true regarding the separation of chromosomes during meiosis?

Accepted Answer

Homologous chromosomes separate during meiosis I, and sister chromatids separate during meiosis II.

Question 19

Which of the following is a function of histone proteins in eukaryotic cells?

Accepted Answer

They help compact DNA by allowing it to wrap around them, forming nucleosomes.

Question 20

A DNA sequence is 5'-ATGCCGTA-3'. What is the complementary sequence, including the correct orientation?

Accepted Answer

$$\displaystyle 3'	ext{-}TACGGCAT	ext{-}5'$$

BIOL-141 Exam 3 Study Guide: Cell Division, Inheritance, and DNA Structure

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