Question 1

Which of the following best explains why DNA, and not protein, is the hereditary material in most organisms?

Accepted Answer

DNA's double-helix structure allows for accurate replication and storage of genetic information.

Question 2

A scientist isolates a circular DNA molecule from a bacterial cell that is separate from the main chromosome. What is this molecule called, and what is its significance?

Accepted Answer

It is a plasmid, which can carry genes such as antibiotic resistance and be transferred between cells.

Question 3

During transcription in eukaryotic cells, which of the following modifications occurs to the pre-mRNA before it exits the nucleus?

Accepted Answer

Addition of a 5' cap, poly-A tail, and removal of introns via splicing.

Question 4

Which of the following statements about the flow of genetic information is correct?

Accepted Answer

Genetic information flows from DNA to RNA to protein, except in retroviruses where it flows from RNA to DNA.

Question 5

A mutation changes the DNA sequence from $$	ext{TAC} to$$ $$	ext{TAA} in a $$gene. If $$	ext{TAC}$$ codes for methionine and $$	ext{TAA} is a $$stop codon, what is the most likely effect on the protein?

Accepted Answer

The protein will be prematurely terminated, likely resulting in loss of function.

Question 6

Which of the following best describes the role of the lac operon in E. coli?

Accepted Answer

It is a set of genes regulated together, allowing the cell to metabolize lactose only when lactose is present and glucose is absent.

Question 7

Which of the following mechanisms can result in the inheritance of gene expression patterns without changes to the DNA sequence?

Accepted Answer

Epigenetic modifications such as DNA methylation and histone acetylation.

Question 8

A researcher uses restriction enzymes to cut DNA and then separates the fragments by size using an electric field. Which technique is being used, and what is its primary purpose?

Accepted Answer

Gel electrophoresis; to analyze and compare DNA fragment sizes.

Question 9

Which of the following best explains how alternative splicing increases protein diversity in eukaryotic cells?

Accepted Answer

By removing different combinations of exons from the pre-mRNA, multiple protein variants can be produced from a single gene.

Question 10

A patient is diagnosed with sickle cell anemia, which is caused by a single nucleotide substitution in the hemoglobin gene. This is an example of which type of mutation?

Accepted Answer

Missense mutation

Question 11

Which of the following statements about prokaryotic and eukaryotic gene expression is correct?

Accepted Answer

In eukaryotes, transcription occurs in the nucleus and translation occurs in the cytoplasm.

Question 12

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

Accepted Answer

tRNA carries amino acids to the ribosome and matches its anticodon to the codon on mRNA.

Question 13

A scientist wants to amplify a specific DNA sequence from a small sample. Which technique should they use, and what is the key enzyme involved?

Accepted Answer

Polymerase Chain Reaction (PCR); Taq polymerase

Question 14

Which of the following is a real-world example of horizontal gene transfer in bacteria?

Accepted Answer

A bacterium acquires antibiotic resistance by receiving a plasmid from another bacterium through conjugation.

Question 15

Which of the following best explains how the binding of transcription factors to promoter regions can affect gene expression?

Accepted Answer

Transcription factors can increase or decrease the rate of transcription by facilitating or blocking the binding of RNA polymerase.

Question 16

A eukaryotic cell differentiates into a muscle cell during development. Which of the following best explains this process?

Accepted Answer

Specific genes for muscle proteins are expressed due to the activation of tissue-specific transcription factors.

Question 17

Which of the following is a possible consequence of a frameshift mutation in a gene?

Accepted Answer

The reading frame of the mRNA is altered, potentially resulting in a nonfunctional protein.

Question 18

Which of the following statements about the genetic code is correct?

Accepted Answer

The genetic code is universal and redundant, meaning most amino acids are encoded by more than one codon.

Question 19

Which of the following best describes the function of reverse transcriptase in retroviruses?

Accepted Answer

It synthesizes DNA from an RNA template, allowing viral genetic material to integrate into the host genome.

AP Biology Unit 6: Gene Expression and Regulation – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards