Question 1

Which of the following statements best explains why the carboxyl group ($-COOH$) in amino acids is considered acidic?

Accepted Answer

It donates hydrogen ions to the environment, lowering pH.

Question 2

A mutation changes a nonpolar side chain in a protein to a polar side chain. Which property of the protein is most likely to be affected?

Accepted Answer

The solubility of the protein in water.

Question 3

Which type of bond is primarily responsible for stabilizing the secondary structure of proteins?

Accepted Answer

Hydrogen bonds between backbone atoms

Question 4

During protein synthesis, which reaction links amino acids together, and what is a key feature of this reaction?

Accepted Answer

Condensation; it requires energy input

Question 5

Which of the following best describes the induced fit model of enzyme activity?

Accepted Answer

The enzyme changes shape to better fit the substrate upon binding.

Question 6

A scientist adds a competitive inhibitor to an enzyme-catalyzed reaction. What is the most likely effect on the reaction rate?

Accepted Answer

The reaction rate decreases because the inhibitor blocks the active site.

Question 7

Which of the following is a function of prions in disease?

Accepted Answer

They cause misfolding of normal proteins, leading to neurodegenerative diseases.

Question 8

Which of the following best describes the backbone of a nucleic acid?

Accepted Answer

It consists of alternating sugar and phosphate groups linked by phosphodiester bonds.

Question 9

If a DNA molecule has 20% adenine, what percentage of guanine does it contain?

Accepted Answer

30%

Question 10

Which of the following statements about RNA is correct?

Accepted Answer

RNA is usually single-stranded and contains uracil instead of thymine.

Question 11

Which factor would most likely increase the rate of an enzyme-catalyzed reaction?

Accepted Answer

Increasing the temperature to the enzyme's optimal range

Question 12

Which of the following interactions is NOT involved in stabilizing tertiary protein structure?

Accepted Answer

Hydrogen bonds between backbone atoms

Question 13

Which process breaks down molecules by adding water, and what is the general equation for this reaction?

Accepted Answer

Hydrolysis; $AB + H_2O \rightarrow A + B$

Question 14

Which of the following is true about the directionality of a polypeptide chain?

Accepted Answer

The C-terminus is at the end with a free carboxyl group.

Question 15

Which of the following best explains why denatured proteins lose their function?

Accepted Answer

Denatured proteins do not fold correctly, so their active sites are disrupted.

Question 16

Which of the following is a correct pairing of nitrogenous bases in DNA?

Accepted Answer

Guanine pairs with cytosine via three hydrogen bonds.

Question 17

Which of the following statements about prion diseases is correct?

Accepted Answer

Prion diseases involve misfolded proteins that induce misfolding in normal proteins.

Question 18

Which of the following is a real-world example of a protein whose function is regulated by changes in shape?

Accepted Answer

Hemoglobin changing shape to bind oxygen

Question 19

Which of the following best describes the role of cofactors in enzyme activity?

Accepted Answer

Cofactors are inorganic ions that assist enzymes in catalysis.

Proteins, Enzymes, and Nucleic Acids: Structure and Function in General Biology

Study Guide - Practice Questions