Question 1

Which of the following best describes the structure of a eukaryotic chromosome during metaphase of mitosis?

Accepted Answer

Two identical sister chromatids joined at a centromere, highly condensed and visible under a light microscope.

Question 2

Which of the following is a key difference between asexual and sexual reproduction?

Accepted Answer

Sexual reproduction involves the fusion of gametes, while asexual reproduction does not.

Question 3

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

Accepted Answer

S phase; each chromosome is duplicated to form two sister chromatids.

Question 4

Which of the following best explains how cell cycle checkpoints help prevent cancer?

Accepted Answer

They detect DNA damage and can halt the cell cycle to allow for repair or trigger apoptosis if the damage is irreparable.

Question 5

A researcher is studying a population of bacteria that reproduce by binary fission. Which of the following steps occurs first in binary fission?

Accepted Answer

The bacterial chromosome is replicated.

Question 6

Which of the following statements about proto-oncogenes is correct?

Accepted Answer

Proto-oncogenes encode proteins that stimulate normal cell growth and division.

Question 7

A cell with a diploid number of $$2n = 8$$ undergoes meiosis. How many chromosomes will each gamete contain after meiosis II?

Accepted Answer

$$4$$

Question 8

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

Accepted Answer

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

Question 9

A geneticist is analyzing a pedigree for a rare genetic disorder. The disorder appears in every generation and affects both males and females equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 10

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 carry different alleles, while sister chromatids are identical copies formed during DNA replication.

Question 11

A human cell in G1 phase contains 46 chromosomes. After S phase, how many DNA molecules and chromosomes are present in the cell?

Accepted Answer

46 chromosomes and 92 DNA molecules

Question 12

Which of the following events during meiosis leads to independent assortment of alleles?

Accepted Answer

Random alignment of homologous chromosome pairs at the metaphase I plate

Question 13

A couple, both heterozygous for a recessive genetic disorder ($$Aa$$), want to know the probability that their child will have the disorder. What is the probability?

Accepted Answer

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

Question 14

Which of the following best explains why Mendel's choice of pea plants was advantageous for his genetic experiments?

Accepted Answer

Pea plants have easily distinguishable traits and can self- or cross-pollinate.

Question 15

A cell is observed to have lost function in a tumor suppressor gene. Which of the following is a likely consequence?

Accepted Answer

The cell may divide uncontrollably, increasing the risk of cancer.

Question 16

Which of the following best describes nondisjunction and its potential outcome in humans?

Accepted Answer

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate, potentially resulting in gametes with abnormal chromosome numbers, such as in Down syndrome.

Question 17

In a dihybrid cross between two individuals heterozygous for both traits ($$AaBb 	imes AaBb$$), what is the expected phenotypic ratio among the offspring, assuming independent assortment?

Accepted Answer

$$9:3:3:1$$

Question 18

Which of the following statements about sex-linked traits in humans is correct?

Accepted Answer

Males are more likely to express X-linked recessive traits because they have only one X chromosome.

Question 19

A cell biologist is culturing mammalian cells to study the effects of a new drug on the cell cycle. Which phase would be most appropriate to analyze if the drug is suspected to block DNA synthesis?

Accepted Answer

S phase

Question 20

Which of the following best describes the difference between the pangenesis and germ-plasm theories of inheritance?

Accepted Answer

Pangenesis proposes that all parts of the body contribute hereditary information, while germ-plasm theory states that only germ cells transmit genetic information.

Comprehensive Study Guide for Chromosomes, Cell Division, Genetics, and Inheritance

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