Biology 9th Chap 7 : Topic 2 - Maryam Publications

Biology Chapter 7 : Topic 2

Enzymes and Their Characteristics

1 / 15

Which statement best defines an enzyme?

A) A hormone that controls body functions

B) A protein that speeds up chemical reactions without being consumed

C) A mineral required for growth

D) A nutrient that provides energy to cells

2 / 15

Why are enzymes called biological catalysts?

A) They stop unwanted reactions.

B) They are produced only by plants.

C) They provide energy to reactions.

D) They increase the rate of reactions without being used up.

3 / 15

Which of the following is a characteristic of enzymes?

A) They can catalyze every type of reaction.

B) They are consumed during reactions.

C) They are highly specific in their action.

D) They work equally well at all temperatures.

4 / 15

An enzyme acts only on a particular substrate because of its:

A) Solubility in water

B) Large size

C) Color

D) Specific three-dimensional shape

5 / 15

Which statement provides evidence that enzymes are proteins?

A) They contain carbon.

B) They are produced by living cells.

C) They speed up reactions.

D) They become denatured at very high temperatures.

6 / 15

A student heats an enzyme solution to 90°C. What is the most likely effect?

A) The enzyme changes into a substrate.

B) The enzyme is denatured and loses activity.

C) The enzyme becomes more active permanently.

D) The enzyme reproduces rapidly.

7 / 15

Which characteristic allows a small amount of enzyme to be used repeatedly?

A) Enzymes provide energy.

B) Enzymes continuously reproduce.

C) Enzymes are not changed permanently during reactions.

D) Enzymes are living cells.

8 / 15

What happens when the pH becomes extremely unsuitable for an enzyme?

A) The enzyme may become denatured.

B) The enzyme forms new substrates.

C) The enzyme becomes a hormone.

D) The enzyme increases its activity indefinitely.

9 / 15

Which statement correctly describes enzyme specificity?

A) Enzymes work without substrates.

B) One enzyme can catalyze all metabolic reactions.

C) An enzyme acts on a particular substrate only.

D) Every substrate can fit into any enzyme.

10 / 15

Why are enzymes important for living organisms?

A) They provide oxygen for respiration.

B) They store genetic information.

C) They replace nutrients.

D) They speed up biochemical reactions necessary for life.

11 / 15

Which factor directly affects enzyme activity?

A) Temperature

B) All of the above

C) pH

D) Substrate concentration

12 / 15

If the concentration of substrate increases while enzyme concentration remains constant, the reaction rate will initially:

A) Decrease

B) Increase

C) Stop completely

D) Remain unchanged

13 / 15

Which statement best explains why enzymes are efficient catalysts?

A) They lower the activation energy required for reactions.

B) They increase the activation energy of reactions.

C) They provide ATP directly.

D) They change into products.

14 / 15

A digestive enzyme that breaks down starch will not normally digest proteins because enzymes are:

A) Organic compounds

B) Reusable

C) Specific in action

D) Soluble

15 / 15

Which statement summarizes the characteristics of enzymes most accurately?

A) Enzymes are non-protein substances that are consumed during reactions.

B) Enzymes work only outside living organisms.

C) Enzymes are protein catalysts that are specific, reusable, and affected by temperature and pH.

D) Enzymes provide energy for all cellular activities.

Your score is

0%