High School Biology : Understanding Enzymes

Study concepts, example questions & explanations for High School Biology

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Example Questions

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Example Question #11 : Understanding Enzymes

Which of the following does not affect the activity of enzymes?

Possible Answers:

Activation energy

pH

Inhibitors

Temperature

Correct answer:

Activation energy

Explanation:

Enzyme activity can be affected by environmental factors such as temperature and pH. This is because proteins denature and lose their shape at high temperatures and extreme pHs. Most enzymes prefer to act under a temperature close to body temperature. Optimal pH is usually physiologic at pH 6 to 8; however, digestive enzymes prefer lower pH around 2 to 3 (e.g. pepsin, which makes sense because pepsin works in acidic conditions within the stomach). 

Example Question #12 : Understanding Enzymes

Which of the following is true about enzymes?

Possible Answers:

They are lipids. 

They lower the activation energy of a reaction.

They lower the energy of reactants.

They lower the energy of products. 

They are not catalysts. 

Correct answer:

They lower the activation energy of a reaction.

Explanation:

Enzymes are all proteins, however there are some RNA molecules that have been found to catalyze reactions, but they are termed ribozymes, not enzymes. They speed up reactions by lowering the activation energy of a reaction and do not change the energy states of the reactants or products. 

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