Question 1

Which of the following best describes the role of enzymes in biological systems?

Accepted Answer

Enzymes lower the activation energy, speeding up chemical reactions.

Question 2

A student mixes hydrogen peroxide ($H_2O_2$) with catalase and observes rapid bubbling. What is the most likely explanation for this observation?

Accepted Answer

Catalase is catalyzing the breakdown of $H_2O_2$ into water and oxygen.

Question 3

Which of the following equations correctly represents the breakdown of hydrogen peroxide by catalase?

Accepted Answer

$2H_2O_2 \rightarrow 2H_2O + O_2$

Question 4

If an enzyme is exposed to extreme heat, what is the most likely effect on its activity?

Accepted Answer

The enzyme will be denatured and lose its function.

Question 5

Which statement best explains why enzymes are specific to their substrates?

Accepted Answer

Enzymes have active sites with unique shapes that fit specific substrates.

Question 6

A patient is diagnosed with a genetic disorder that affects the structure of catalase. Which of the following is a likely consequence?

Accepted Answer

The patient will have difficulty breaking down $H_2O_2$, leading to toxic buildup.

Question 7

Which of the following best describes the effect of pH on enzyme activity?

Accepted Answer

Each enzyme has an optimal pH at which it functions best.

Question 8

During a laboratory experiment, a student observes that catalase works fastest at 37°C. What is the most likely reason for this observation?

Accepted Answer

37°C is the optimal temperature for catalase activity in humans.

Question 9

Which of the following is NOT a property of enzymes?

Accepted Answer

Enzymes are consumed during the reaction.

Question 10

A scientist adds more substrate to a solution containing a fixed amount of enzyme. What is the expected result?

Accepted Answer

The reaction rate will increase until the enzyme becomes saturated.

Question 11

Which of the following best explains why hydrogen peroxide ($H_2O_2$) is toxic to cells?

Accepted Answer

$H_2O_2$ can damage cellular components by producing reactive oxygen species.

Question 12

Which of the following would most likely inhibit the activity of catalase?

Accepted Answer

Adding a competitive inhibitor that binds to the active site.

Question 13

A mutation causes the active site of an enzyme to change shape. What is the most likely consequence?

Accepted Answer

The enzyme will no longer bind its substrate effectively.

Question 14

Which of the following is the correct definition of activation energy?

Accepted Answer

The energy required to start a chemical reaction.

Question 15

In a real-world scenario, why is it important for liver cells to contain high levels of catalase?

Accepted Answer

Liver cells frequently encounter $H_2O_2$ as a byproduct of metabolism and need to break it down quickly.

Question 16

Which of the following best describes the lock-and-key model of enzyme action?

Accepted Answer

The enzyme's active site fits the substrate exactly, allowing for specific binding.

Question 17

A researcher finds that catalase activity decreases sharply at pH 4. What is the most likely explanation?

Accepted Answer

Catalase is denatured at low pH, losing its functional shape.

Question 18

Which of the following is a multi-step process involving enzyme action in the human body?

Accepted Answer

Detoxification of $H_2O_2$ by catalase, followed by the removal of water and oxygen as waste products.

Question 19

Which of the following would most likely result from a deficiency of catalase in red blood cells?

Accepted Answer

Accumulation of $H_2O_2$ leading to oxidative damage.

Cell Structure and Function: Study Notes for General Biology

Study Guide - Practice Questions