Question 1

Which phase in the diagram above (I–V) corresponds to the S phase of the cell cycle, and what key event occurs during this phase?

Accepted Answer

Phase II; DNA replication occurs, doubling the amount of DNA.

Question 2

During which phase of mitosis do chromosomes first become visible under a light microscope?

Accepted Answer

Prophase

Question 3

What is the role of the spindle apparatus during mitosis?

Accepted Answer

It separates sister chromatids during anaphase.

Question 4

If a cell has 8 chromosomes during G1, how many chromatids will it have during metaphase of mitosis?

Accepted Answer

$$16$$

Question 5

Which of the following best describes the arrangement of chromosomes during metaphase?

Accepted Answer

Chromosomes align at the metaphase plate, equidistant from the spindle poles.

Question 6

What is the function of telomerase in eukaryotic cells?

Accepted Answer

It adds repetitive sequences to the ends of chromosomes to prevent shortening.

Question 7

Which enzyme is responsible for joining Okazaki fragments on the lagging strand during DNA replication?

Accepted Answer

DNA ligase

Question 8

A mutation causes nondisjunction during meiosis. What is the most likely outcome?

Accepted Answer

Gametes with abnormal numbers of chromosomes are produced.

Question 9

Which of the following increases genetic variation in sexually reproducing species?

Accepted Answer

Crossing over during prophase I of meiosis

Question 10

What is the function of the spliceosome in eukaryotic cells?

Accepted Answer

It removes introns from pre-mRNA and joins exons together.

Question 11

Which of the following best describes a karyotype?

Accepted Answer

A visual display of all the chromosomes in a cell, arranged by size and shape.

Question 12

Which chemical bonds hold the two strands of the DNA double helix together?

Accepted Answer

Hydrogen bonds between complementary bases

Question 13

What is the function of the SRY gene in humans?

Accepted Answer

It initiates the development of male characteristics.

Question 14

Which of the following is an example of incomplete dominance?

Accepted Answer

A red-flowered plant crossed with a white-flowered plant produces pink-flowered offspring.

Question 15

Which process describes the exchange of genetic material between homologous chromosomes during meiosis?

Accepted Answer

Crossing over

Question 16

If the percentage of cytosine (C) in a DNA molecule is 20%, what is the percentage of adenine (A)?

Accepted Answer

$$30\%$$

Question 17

Which of the following best describes pleiotropy?

Accepted Answer

One gene affects multiple phenotypic traits.

Question 18

What is a ribozyme?

Accepted Answer

An RNA molecule that acts as an enzyme.

Question 19

Which of the following mutations involves a segment of a chromosome breaking off and attaching to a non-homologous chromosome?

Accepted Answer

Translocation

Question 20

Which phase in the diagram above (I–V) represents the G1 phase, and what is the main event occurring during this phase?

Accepted Answer

Phase I; cell grows and carries out normal metabolic functions.

Exam 3

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