The graph below represents the effect of pH on three different enzymes at normal body temperature. The Effect of pH on Three Different Enzymes at Normal Body Temperature Relative Rate of Enzyme Activity 4- 3- 2- 1- 2 4 6 8 10 12 PH The graph illustrates that enzyme 1, 2, and 3 (1) Are not affected by pH (2) Work best at different pH levels (3) Work best in acidic environment (4) Work best in a basic environment Key Enzyme 1 Enzyme 2 Enzyme 3
The Correct Answer and Explanation is:
The correct answer is (2) Work best at different pH levels.
This graph demonstrates the relationship between pH and the activity rate of three different enzymes. Enzymes are highly specific biological catalysts, and their function is heavily dependent on environmental conditions like temperature and pH. The three-dimensional structure of an enzyme, particularly its active site where the substrate binds, is crucial for its activity. Extreme changes in pH can alter the electrical charges on the amino acids that make up the enzyme, causing its shape to change. This process, known as denaturation, can permanently inactivate the enzyme.
Each enzyme has an optimal pH, which is the specific pH at which it functions most efficiently and exhibits its maximum rate of activity. On the provided graph, the optimal pH for each enzyme is represented by the peak of its respective curve.
Analyzing the graph, we can identify the optimal pH for each enzyme:
- Enzyme 1, represented by the short dashed line, shows its highest activity at a pH of approximately 4. This is an acidic environment.
- Enzyme 2, represented by the dotted line, reaches its peak activity at a pH of about 8. This is a slightly basic or alkaline environment.
- Enzyme 3, represented by the long dashed line, functions best at a pH of around 10.5, which is a more strongly basic environment.
Since the three enzymes have different optimal pH values (4, 8, and 10.5), the graph clearly illustrates that they work best at different pH levels. This makes option (2) the correct conclusion. Option (1) is incorrect because the activity of all three enzymes is clearly affected by pH. Options (3) and (4) are incorrect because they are not universally true for all three enzymes; only Enzyme 1 works best in an acidic environment, while Enzymes 2 and 3 work best in basic environments.
