Introduction to Enzymes: Interactive Quizzes for Biochemistry Students

Question 1

Which of the following factors does **not** affect enzyme activity?

Accepted Answer

Gravity

Answer

pH

Answer

Substrate concentration

Answer

Enzyme concentration

Question 2

The portion of an enzyme that binds to and interacts with the substrate is called the:

Accepted Answer

Active site

Answer

Allosteric site

Answer

Cofactor

Answer

Prosthetic group

Question 3

Which type of inhibition is caused by a molecule that binds to the enzyme and changes its conformation, affecting its binding affinity for the substrate?

Accepted Answer

Non-competitive inhibition

Answer

Competitive inhibition

Answer

Uncompetitive inhibition

Answer

Mixed inhibition

Question 4

Which of the following enzymes is **not** involved in DNA replication?

Accepted Answer

RNA polymerase

Answer

DNA polymerase

Answer

Helicase

Answer

Topoisomerase

Question 5

The enzyme that catalyzes the hydrolysis of peptide bonds in proteins is called:

Accepted Answer

Peptidase

Answer

Lipase

Answer

Amylase

Answer

Nuclease

Question 6

Which of the following is a coenzyme?

Accepted Answer

Vitamin B12

Answer

Iron

Answer

Magnesium

Answer

Calcium

Question 7

Enzymes are essential for life because they:

Accepted Answer

Catalyze chemical reactions necessary for life

Answer

Provide energy for the body

Answer

Transport nutrients across membranes

Answer

Regulate gene expression (indirectly)

Question 8

The active site of an enzyme is:

Accepted Answer

A specific region where the substrate binds

Answer

Flexible to accommodate different substrates

Answer

Charged to attract substrates

Answer

Hydrophobic in nature

Question 9

The Michaelis constant (Km) is a measure of:

Accepted Answer

Substrate concentration at half-maximal velocity

Answer

Enzyme-substrate affinity

Answer

Maximum reaction velocity

Answer

Enzyme turnover number

Question 10

Which of the following is an example of an allosteric enzyme?

Accepted Answer

Aspartate transcarbamoylase

Answer

Hexokinase

Answer

Catalase

Answer

Pepsin

Question 11

What is the role of cofactors in enzyme function?

Accepted Answer

To carry electrons or chemical groups

Answer

To provide additional catalytic sites

Answer

To increase enzyme stability

Answer

To activate substrates

Question 12

Which statement about enzymes is inaccurate?

Accepted Answer

Enzymes are consumed in the reactions they catalyze.

Answer

Enzymes are highly specific for their substrates.

Answer

Enzymes remain unchanged after catalyzing a reaction.

Answer

Enzymes accelerate reactions by providing an alternative pathway with a lower activation energy.

Question 13

The Michaelis constant (Km) of an enzyme is a measure of:

Accepted Answer

The substrate concentration at which the enzyme is half-saturated.

Answer

The maximum reaction rate of the enzyme.

Answer

The substrate concentration at which the enzyme is fully saturated.

Answer

The inhibitor concentration at which the enzyme is half-inhibited.

Question 14

Which enzyme classification system is based on the type of reaction catalyzed?

Accepted Answer

EC number system

Answer

IUBMB system

Answer

Bernfeld system

Answer

Dixon system

Question 15

The primary structure of an enzyme refers to its:

Accepted Answer

Sequence of amino acids.

Answer

Three-dimensional structure.

Answer

Number of subunits.

Answer

Presence of cofactors.

Question 16

Which enzyme is an example of an allosteric enzyme?

Accepted Answer

Aspartate transcarbamoylase

Answer

Hexokinase

Answer

Catalase

Answer

Superoxide dismutase

Question 17

The enzyme-substrate complex forms when the:

Accepted Answer

Enzyme and substrate bind together.

Answer

Product is released.

Answer

Enzyme breaks down the substrate.

Answer

Enzyme undergoes denaturation.

Question 18

Cofactors serve as:

Accepted Answer

Inorganic ions or organic molecules that assist enzyme activity.

Answer

Substrates upon which enzymes act.

Answer

Products resulting from enzyme reactions.

Question 19

Which enzyme aids in protein digestion?

Accepted Answer

Pepsin

Answer

Lipase

Answer

Sucrase

Answer

Amylase

Question 20

Distinguish between a holoenzyme and an apoenzyme:

Accepted Answer

A holoenzyme is an enzyme with a bound cofactor, while an apoenzyme lacks a cofactor.

Answer

A holoenzyme has a single polypeptide chain, while an apoenzyme has multiple subunits.

Answer

A holoenzyme is inactive, while an apoenzyme is active.

Question 21

The Michaelis constant (Km) of an enzyme represents:

Accepted Answer

The substrate concentration at half of the enzyme's maximum velocity.

Answer

The enzyme's maximum velocity.

Answer

The substrate concentration at enzyme saturation.

Question 22

Which of the following is the best definition of an enzyme?

Accepted Answer

A protein catalyst that increases the rate of a chemical reaction without being consumed

Answer

A non-protein molecule that binds to a substrate and increases its reactivity

Answer

A metal ion that participates in a chemical reaction and is regenerated at the end

Question 23

Which of the following is an example of an enzyme cofactor?

Accepted Answer

NAD+

Answer

Iron

Answer

Vitamin B12

Answer

Magnesium

Question 24

The enzyme-substrate complex is formed when the enzyme:

Accepted Answer

Binds to the substrate at the active site

Answer

Catalyzes the reaction

Answer

Is denatured

Answer

Undergoes a conformational change