Question 1

Which phase in the diagram above (I, II, III, IV, or 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 in the nucleus.

Question 2

During which phase in the diagram does the amount of DNA in the nucleus decrease, and what cellular process is responsible for this change?

Accepted Answer

Phase V; cytokinesis divides the cytoplasm, resulting in two cells with half the original DNA content.

Question 3

What is the primary function of the spindle apparatus during mitosis?

Accepted Answer

To attach to centromeres and separate sister chromatids during anaphase.

Question 4

If a cell has 8 chromosomes at the start of G1, how many chromatids and chromosomes will it have at metaphase II of meiosis?

Accepted Answer

4 chromosomes and 8 chromatids

Question 5

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

Accepted Answer

Chromosomes are aligned single file along the metaphase plate.

Question 6

What is the significance of the G1 checkpoint in the cell cycle?

Accepted Answer

It checks for DNA damage and determines if the cell will proceed to DNA synthesis.

Question 7

Which process increases genetic variation during meiosis and when does it occur?

Accepted Answer

Crossing over; during prophase I

Question 8

Which of the following is true about introns and exons in eukaryotic genes?

Accepted Answer

Introns are removed from the mRNA by the spliceosome.

Question 9

A dihybrid cross between two heterozygous individuals (AaBb x AaBb) will produce what phenotypic ratio in the offspring, assuming independent assortment and complete dominance?

Accepted Answer

9:3:3:1

Question 10

Which enzyme is responsible for joining Okazaki fragments during DNA replication?

Accepted Answer

DNA ligase

Question 11

What is the function of telomerase in eukaryotic cells?

Accepted Answer

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

Question 12

Which of the following best describes a ribozyme?

Accepted Answer

An RNA molecule with catalytic activity.

Question 13

If a DNA sample contains 30% adenine (A), what is the percentage of cytosine (C) in the sample?

Accepted Answer

$$C = 20\%$$

Question 14

Which type of chemical bond holds the two strands of the DNA double helix together?

Accepted Answer

Hydrogen bonds

Question 15

What is the effect of a nondisjunction mutation during meiosis?

Accepted Answer

It results in chromosomes failing to separate properly, leading to gametes with abnormal chromosome numbers.

Question 16

Which gene is responsible for initiating male sex determination in humans?

Accepted Answer

SRY gene

Question 17

Which of the following best explains polygenic inheritance?

Accepted Answer

Multiple genes contribute to a single trait, resulting in continuous variation.

Question 18

What is the expected frequency of crossing over between two genes that are very far apart on the same chromosome?

Accepted Answer

Close to 50%

Question 19

Which of the following is true about complete dominance?

Accepted Answer

The dominant allele completely masks the effect of the recessive allele in the heterozygote.

Question 20

Which of the following best describes the difference between a somatic cell and a gamete?

Accepted Answer

Somatic cells are diploid, gametes are haploid.

Cell Cycle, Chromosome Structure, and Genetics Study Guide – Step-by-Step Guidance

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