IGCSE Biology Paper-1: Specimen Questions with Answers 169 - 169 of 208
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Question 169
Question
MCQ▾Two enzyme-controlled reactions are shown.
From these reactions, what deduction can be made about enzymes?
Choices
| Choice (4) | |
|---|---|
a. | Enzyme 2 slows down the production of amino acids. |
b. | Enzymes can build up large molecules. |
c. | Enzymes only break down large molecules. |
d. | Enzyme 1 has been changed to enzyme 2. |
Answer
b.Explanation
Properties of Enzymes
- Enzymes are complex macromolecules with high molecular weight.
- They catalyse biochemical reactions in a cell. They help in the breakdown of large molecules into smaller molecules or bring together two smaller molecules to form a larger molecule.
- Enzymes do not start a reaction. However, they help in accelerating it.
- Enzymes affect the rate of biochemical reaction and not the direction of the reaction.
- Most of the enzymes have a high turnover number. Turnover number of an enzyme is the number of molecules of a substance that is acted upon by an enzyme per minute under saturated substrate concentration. High turnover number of enzymes increases the efficiency of the reaction.
- Enzymes are specific in action.
- Enzymatic activity decreases with increase in temperature and all enzymes show maximum activity at an optimum of .
- They show maximum activity at an optimum pH of 6 – 8.
- The velocity of enzyme increases with increase in substrate concentration and then, reaches maximum velocity.