Question 1

Which of the following best explains why meiosis, but not mitosis, leads to genetic variation in offspring?

Accepted Answer

Meiosis includes processes such as independent assortment and crossing over, which shuffle genetic material.

Question 2

A patient is diagnosed with a malignant tumor. Which of the following characteristics would most likely be observed in the tumor cells?

Accepted Answer

The cells divide uncontrollably and can invade other tissues through metastasis.

Question 3

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

Accepted Answer

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

Question 4

A woman who is heterozygous for a recessive genetic disorder (Aa) and a man who is homozygous dominant (AA) have a child. What is the probability that their child will be a carrier of the disorder?

Accepted Answer

$$50\%$$

Question 5

Which of the following best describes the structure of a DNA molecule?

Accepted Answer

A double helix with a sugar-phosphate backbone and nitrogenous base pairs (A-T and C-G) held together by hydrogen bonds.

Question 6

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

Accepted Answer

$$4$$

Question 7

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

Accepted Answer

Autosomal dominant

Question 8

Which of the following events occurs during anaphase of mitosis?

Accepted Answer

Sister chromatids are pulled apart toward opposite poles of the cell.

Question 9

A mutation changes the DNA sequence from $$	ext{TACGGA} to$$ $$	ext{TAGGGA}. $$What type of mutation is this, and what is its likely effect?

Accepted Answer

Substitution; may change a single amino acid in the protein.

Question 10

Which of the following best explains Mendel’s Law of Segregation?

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 11

Which of the following scenarios is an example of incomplete dominance?

Accepted Answer

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

Question 12

During DNA replication, which enzyme is responsible for adding new nucleotides to the growing DNA strand?

Accepted Answer

DNA polymerase

Question 13

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 recessive X-linked trait?

Accepted Answer

$$50\%$$

Question 14

Which of the following best describes the difference between benign and malignant tumors?

Accepted Answer

Benign tumors do not spread to other parts of the body, while malignant tumors can metastasize.

Question 15

Which of the following statements about the central dogma of molecular biology is correct?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 16

A child is born with Down syndrome due to nondisjunction. Which of the following best describes what happened during meiosis?

Accepted Answer

Homologous chromosomes or sister chromatids failed to separate, resulting in an extra chromosome 21.

Question 17

Which of the following is true about the difference between DNA and RNA?

Accepted Answer

DNA uses thymine, while RNA uses uracil as a nitrogenous base.

Question 18

Which of the following best explains how independent assortment during meiosis increases genetic diversity?

Accepted Answer

It causes each pair of homologous chromosomes to separate independently, resulting in many possible combinations of maternal and paternal chromosomes in gametes.

Question 19

Which of the following best describes a frameshift mutation and its likely effect on a protein?

Accepted Answer

A base is inserted or deleted, altering the reading frame and usually resulting in a nonfunctional protein.

Question 20

A cell is observed to have twice the normal amount of DNA, but has not yet begun to condense its chromosomes. In which phase of the cell cycle is this cell most likely to be?

Accepted Answer

G2 phase

Cell Division, Genetics, and DNA: Study Guide for General Biology

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