Question 1

Which of the following best describes the primary function of proteins in living organisms?

Accepted Answer

They perform a vast array of biological activities, including catalyzing chemical reactions, transporting substances, and providing structural support.

Question 2

A polypeptide is best defined as:

Accepted Answer

A chain of amino acids linked by peptide bonds.

Question 3

Which of the following amino acids is classified as basic based on its side chain properties?

Accepted Answer

Lysine

Question 4

Enzymes are able to speed up chemical reactions in cells because they:

Accepted Answer

Lower the activation energy required for the reaction.

Question 5

Which of the following statements about enzyme active sites is correct?

Accepted Answer

The active site binds substrates and positions them for the chemical reaction.

Question 6

A mutation changes a hydrophobic amino acid in the core of a protein to a hydrophilic one. What is the most likely effect on the protein's structure?

Accepted Answer

The protein may misfold or lose its functional shape.

Question 7

Which of the following best explains why enzymes are specific to their substrates?

Accepted Answer

The shape and chemical properties of the active site match only certain substrates.

Question 8

In the glycolysis pathway, which molecule is the final product after all enzymatic steps?

Accepted Answer

Pyruvate

Question 9

Which of the following best describes a metabolic pathway?

Accepted Answer

A series of enzyme-catalyzed steps that transform one molecule into another.

Question 10

Which of the following is a function of enzyme cofactors?

Accepted Answer

They are required for the enzyme to carry out its specific chemical reaction.

Question 11

A scientist is studying a metabolic pathway in which Molecule A is converted to Molecule D through three enzyme-catalyzed steps. If Enzyme 2 is inhibited, what will most likely happen?

Accepted Answer

Molecule B will accumulate, and the pathway will stop at that step.

Question 12

Which of the following best describes the role of phosphorylation in regulating enzyme activity?

Accepted Answer

It can turn enzymes on or off by adding a phosphate group.

Question 13

Which of the following statements about metabolism is correct?

Accepted Answer

Metabolism is the sum of all chemical reactions occurring in an organism.

Question 14

Which of the following amino acids is most likely to be found on the surface of a soluble protein in the cytoplasm?

Accepted Answer

Glutamic acid

Question 15

A patient has a genetic mutation that prevents the production of a specific enzyme in glycolysis. Which of the following is a likely consequence?

Accepted Answer

The patient will have impaired ability to break down glucose for energy.

Question 16

Which of the following best explains why humans must obtain some amino acids from their diet?

Accepted Answer

Humans lack the metabolic pathways to synthesize 9 of the 20 amino acids.

Question 17

Which of the following is true about the chemical structure of amino acids?

Accepted Answer

Each amino acid has a unique side chain (R group) that determines its properties.

Question 18

Which of the following best describes the relationship between enzymes and metabolic pathways?

Accepted Answer

Each step in a metabolic pathway is catalyzed by a different enzyme.

Question 19

Which of the following is a product of the glycolysis pathway?

Accepted Answer

Pyruvate

Question 20

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

Accepted Answer

The inhibitor binds to the active site, preventing substrate binding.

Proteins, Amino Acids, and Metabolism: Core Concepts in General Biology

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