Question 1

During meiosis, crossing over is a critical event that increases genetic diversity. At which specific stage does crossing over occur, and what is its biological significance?

Accepted Answer

Crossing over occurs during prophase I and leads to the exchange of genetic material between homologous chromosomes, increasing genetic variation.

Question 2

A woman with genotype $$I^A I^O$$ and a man with genotype $$I^B I^O$$ have a child. What is the probability that their child will have blood type O?

Accepted Answer

$$0.25$$

Question 3

Which of the following best describes the difference between complete dominance and incomplete dominance?

Accepted Answer

In complete dominance, the dominant allele completely masks the recessive allele in the heterozygote, while in incomplete dominance, the heterozygote shows a blend of both alleles.

Question 4

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

Accepted Answer

Autosomal dominant

Question 5

If a DNA sample contains $$30\%$$ adenine, what percentage of guanine would you expect to find?

Accepted Answer

$$20\%$$

Question 6

Which enzyme is responsible for synthesizing the new DNA strand during DNA replication, and what is a key characteristic of this enzyme?

Accepted Answer

DNA polymerase; it adds nucleotides to the 3' end and proofreads for errors.

Question 7

A mutation changes a codon from $$UAC ($$tyrosine) to $$UAA ($$stop codon). What type of mutation is this, and what is its likely effect on the protein?

Accepted Answer

Nonsense mutation; results in premature termination of translation.

Question 8

Which of the following best explains why DNA moves toward the positive electrode during gel electrophoresis?

Accepted Answer

DNA is negatively charged due to its phosphate backbone.

Question 9

A woman who is a carrier for a sex-linked recessive disorder (X-linked) and a man who does not have the disorder have a son. What is the probability that their son will have the disorder?

Accepted Answer

$$0.5$$

Question 10

Which of the following statements about the semiconservative model of DNA replication is correct?

Accepted Answer

Each new DNA molecule consists of one parental strand and one newly synthesized strand.

Question 11

Which of the following best describes the function of tRNA during translation?

Accepted Answer

tRNA brings specific amino acids to the ribosome by matching its anticodon to the codon on mRNA.

Question 12

Which of the following is a consequence of nondisjunction during meiosis II in human oogenesis?

Accepted Answer

Half of the gametes will be normal, and half will have either an extra or missing chromosome.

Question 13

Which of the following best explains why individuals with Down syndrome have three copies of chromosome 21?

Accepted Answer

Nondisjunction during meiosis leads to an extra copy of chromosome 21 in the gamete.

Question 14

Which of the following is NOT a difference between prokaryotic and eukaryotic cells?

Accepted Answer

Prokaryotic cells have a nucleus; eukaryotic cells do not.

Question 15

Which of the following best describes the role of restriction enzymes in molecular biology?

Accepted Answer

They cut DNA at specific nucleotide sequences, allowing for DNA manipulation.

Question 16

A scientist wants to amplify a specific DNA segment using PCR. Which of the following materials is NOT required in the PCR reaction?

Accepted Answer

RNA polymerase

Question 17

Which of the following best explains why a testcross is used in genetics?

Accepted Answer

To determine the genotype of an individual with a dominant phenotype by crossing with a homozygous recessive individual.

Question 18

Which of the following statements about the structure of DNA is correct?

Accepted Answer

The two strands of DNA are held together by hydrogen bonds between complementary bases.

Question 19

Which of the following best describes the relationship between genotype and phenotype?

Accepted Answer

Genotype determines the phenotype, but environmental factors can also influence phenotype.

Comprehensive Study Guide for College Biology: Cell Replication, Genetics, and Molecular Biology

Study Guide - Practice Questions

Study Guide - Flashcards