Question 1

A recent study suggests that the bright coloration of some crayfish species evolved not as an adaptation, but as a result of which evolutionary process?

Accepted Answer

Random genetic drift (evolutionary accident)

Question 2

Which of the following best describes a mutation?

Accepted Answer

A change in the DNA sequence of an organism

Question 3

Why are only mutations that occur in germline cells heritable?

Accepted Answer

Because only germline cells contribute genetic material to offspring

Question 4

A point mutation changes a codon from GAA to GAG, both of which code for glutamic acid. What type of mutation is this?

Accepted Answer

Synonymous (silent) mutation

Question 5

Which of the following equations correctly represents a transition mutation?

Accepted Answer

$$A \rightarrow G$$

Question 6

A mutation in the regulatory region of a gene results in the gene being expressed at the wrong time or place. What is this type of mutation called?

Accepted Answer

Ectopic mutation

Question 7

A patient with kidney cancer has a synonymous mutation in the BAP1 gene that leads to exon skipping. What is the most likely consequence?

Accepted Answer

Loss of function due to frameshift and early stop codon

Question 8

Which of the following best explains why the lactose tolerance mutation became common in certain human populations?

Accepted Answer

It arose randomly and provided a selective advantage in milk-drinking societies

Question 9

Which of the following is a possible consequence of a nonsense mutation occurring early in an open reading frame?

Accepted Answer

Nonsense-mediated decay leading to no mRNA or protein

Question 10

A frameshift mutation is most likely caused by which of the following?

Accepted Answer

An insertion or deletion of nucleotides not in multiples of three

Question 11

Which laboratory technique would you use to detect changes in mRNA levels resulting from a gene mutation?

Accepted Answer

Northern blot

Question 12

A mutation in the Ras gene results in the protein being constitutively active. What is the most likely outcome?

Accepted Answer

Uncontrolled cell proliferation and increased cancer risk

Question 13

Which of the following best describes a transversion mutation?

Accepted Answer

$$A \rightarrow T$$

Question 14

Which of the following is NOT a possible cause of DNA mutation?

Accepted Answer

Accurate base pairing during replication

Question 15

A trinucleotide repeat disorder is most likely caused by which molecular mechanism?

Accepted Answer

Strand slippage during DNA replication

Question 16

Which of the following best explains why only half of the F1 generation will carry a germline mutation?

Accepted Answer

Because only one gamete (egg or sperm) carries the mutation

Question 17

Which of the following is a possible effect of a mutation in a non-coding region of DNA?

Accepted Answer

Disruption of transcription, splicing, or translation

Question 18

Which of the following best describes a null mutation?

Accepted Answer

A mutation that results in a non-functional or absent protein

Question 19

Which of the following is an example of a conservative missense mutation?

Accepted Answer

Lysine to arginine

Question 20

Which of the following best explains how a synonymous mutation can lead to loss of gene function?

Accepted Answer

By creating or disrupting an exonic splicing enhancer, leading to exon skipping

DNA Mutations: Causes, Types, and Consequences

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