Question 1

A mutation occurs in a non-gene portion of DNA. Which of the following is the most likely outcome?

Accepted Answer

The mutation may have no effect, but could alter gene regulation if it occurs in a regulatory region such as an enhancer.

Question 2

Which of the following best describes the role of enhancer regions in gene expression?

Accepted Answer

Enhancers are DNA sequences that increase the likelihood of transcription when bound by activator proteins.

Question 3

A mutation in the jaw enhancer region of the Pitx1 gene prevents binding of the activator protein. What is the most likely result?

Accepted Answer

Pitx1 will not be expressed in the jaw.

Question 4

Which of the following mechanisms is NOT a way eukaryotic cells regulate gene expression?

Accepted Answer

DNA replication errors

Question 5

Lactose intolerance in adults is primarily due to which of the following molecular events?

Accepted Answer

A decrease in transcription factor binding at the lactase gene enhancer after weaning.

Question 6

Which of the following changes could explain the continued expression of the LCT gene into adulthood?

Accepted Answer

Increased production of activator protein

Question 7

A single nucleotide polymorphism (SNP) occurs 13,910 base pairs upstream of the lactase gene, changing a C to a T. This mutation increases the binding affinity of the Oct-1 transcription factor. What is the most likely effect?

Accepted Answer

Increased transcription of the lactase gene

Question 8

Which of the following best explains why some populations have a high frequency of lactase persistence?

Accepted Answer

Positive selection for individuals who could digest milk, providing nutritional and reproductive advantages.

Question 9

Which of the following is a direct consequence of undigested lactose passing into the large intestine?

Accepted Answer

Cramping, diarrhea, and gas due to bacterial fermentation

Question 10

Which of the following equations best represents the hydrolysis of lactose by lactase?

Accepted Answer

$$\mathrm{Lactose} + \mathrm{H}_2\mathrm{O} \xrightarrow{\mathrm{lactase}} \mathrm{Glucose} + \mathrm{Galactose}$$

Question 11

Which of the following best describes the relationship between transcription factors and gene expression?

Accepted Answer

Transcription factors bind to DNA and can either increase or decrease the rate of gene transcription.

Question 12

A population of stickleback fish in a shallow pond has a high frequency of individuals with reduced pelvic fins. Which genetic mechanism most likely explains this trait?

Accepted Answer

A mutation in the pelvic enhancer region of the Pitx1 gene prevents expression in the pelvis.

Question 13

Which of the following is an example of post-transcriptional control of gene expression?

Accepted Answer

RNA splicing to remove introns from pre-mRNA

Question 14

Which of the following scenarios would most likely result in increased gene expression?

Accepted Answer

A mutation in an enhancer region that increases activator protein binding

Question 15

Which of the following best explains why a mutation in a regulatory region can have tissue-specific effects?

Accepted Answer

Different tissues use different enhancer regions to control gene expression.

Question 16

Which of the following is a plausible evolutionary advantage of lactase persistence in Neolithic populations?

Accepted Answer

Increased reproductive success due to access to a reliable food source

Question 17

Which of the following statements about gene expression is correct?

Accepted Answer

A gene is expressed when it is transcribed, translated, and properly processed to produce a protein.

Question 18

Which of the following best describes the effect of smoking a pack of cigarettes a day for a year on lung cells?

Accepted Answer

It leaves approximately 150 mutations in every lung cell.

Question 19

Which of the following is a multi-step process that can lead to the production of a functional protein from a gene?

Accepted Answer

Transcription, RNA processing, translation, and protein folding

Gene Regulation, Mutations, and Evolutionary Adaptations: The Case of Lactase Persistence and Stickleback Fish

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