Question 1

Which of the following best describes the type of bond that holds together the two strands of a DNA double helix?

Accepted Answer

Hydrogen bonds

Question 2

A mutation changes a codon from $$	ext{UAC} to$$ $$	ext{UAA}. $$What is the most likely effect of this mutation on the resulting protein?

Accepted Answer

It will introduce a premature stop codon, leading to a truncated protein.

Question 3

Which of the following steps occurs first during gene expression in a eukaryotic cell?

Accepted Answer

Transcription in the nucleus

Question 4

A researcher finds a DNA sample with 32% adenine. According to Chargaff's rules, what percentage of guanine should be present in this DNA?

Accepted Answer

$$18\%$$

Question 5

Which of the following amino acid substitutions is most likely to disrupt the function of a protein by altering its tertiary structure?

Accepted Answer

Aspartic acid to valine

Question 6

Which of the following best explains why facilitated diffusion requires membrane proteins?

Accepted Answer

It allows polar or charged molecules to cross the hydrophobic lipid bilayer.

Question 7

During translation, which molecule brings amino acids to the ribosome?

Accepted Answer

tRNA

Question 8

A cell is placed in a solution with a higher concentration of solutes than inside the cell. What will most likely happen to the cell?

Accepted Answer

Water will move out of the cell, causing it to shrink.

Question 9

Which of the following best describes the role of the ribosome in gene expression?

Accepted Answer

It catalyzes the formation of peptide bonds between amino acids.

Question 10

A DNA sequence is 5'-ATGCGT-3'. What is the sequence of the complementary DNA strand?

Accepted Answer

3'-TACGCA-5'

Question 11

Which of the following changes would most likely increase the rate of facilitated diffusion across a cell membrane?

Accepted Answer

Increasing the concentration gradient of the transported molecule

Question 12

Which of the following best describes the relationship between DNA, mRNA, and protein in the central dogma of molecular biology?

Accepted Answer

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

Question 13

A mutation in the spike protein of a virus changes a polar amino acid at the binding site to a non-polar amino acid. What is the most likely effect on the virus's ability to bind to its receptor?

Accepted Answer

It will decrease binding if the receptor site is polar.

Question 14

Which of the following best describes a silent mutation?

Accepted Answer

A mutation that does not change the amino acid sequence of the protein

Question 15

Which of the following correctly matches a step in gene expression with its cellular location in a eukaryotic cell?

Accepted Answer

Transcription: nucleus

Question 16

Which of the following best explains why a change from aspartic acid to glutamic acid is less likely to disrupt protein function than a change from aspartic acid to valine?

Accepted Answer

Aspartic acid and glutamic acid are both negatively charged.

Question 17

Which of the following best describes the function of mRNA in the process of gene expression?

Accepted Answer

It serves as a template for protein synthesis.

Question 18

A cell needs to synthesize a protein that will be secreted from the cell. Which cellular structure is most directly involved in this process?

Accepted Answer

Ribosome on the rough endoplasmic reticulum

Question 19

Which of the following best describes the role of hydrogen bonds in the structure of DNA?

Accepted Answer

They hold the two complementary strands together.

Question 20

Which of the following scenarios would most likely result in a frameshift mutation?

Accepted Answer

A single base insertion

Proteins, Gene Expression, and Nucleic Acids: Structure, Function, and Exam Practice

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