Question

Regarding the graph, assertion and reason; choose the correct option, where X Axis is Temperature and Y axis is Enzyme activity.

Assertion [A]: The graph of Rate of Enzyme activity vs Temperature is always a
parabola.

Reason [R]: Enzyme activity always increases with rise in temperature.

\( x \)-axis

• A. Assertion [A] is True and Reason [R] is False.
• B. Reason [R] is True and Assertion [A] is False.
• C. Assertion [A] is True and Reason [R] is True and is a correct explanation to [A].
• D. Assertion [A] is True and Reason [R] is True but is not a correct explanation to [A].

Answer 1

The correct option is D

Explanation of the correct option:

1. The graph indicates the rate of enzymatic activity (Y - axis) based on increase in temperature (X- axis).
2. As the temperature increases up to a certain level, the rate of enzymatic activity too, increases. It happens so till a certain limit is reached.
3. This threshold is called the Optimum temperature.
4. This is usually around ${37.5}^{\circ }$ C which is also the normal human body temperature.
5. But, any further increase in temperature, although should theoretically, increase the rate of activity, it does not because, the protein structure of the enzyme would start to break apart. This is also known as thermal denaturation.
6. Therefore, the answer is D even though the reason is true.

Final answer: Assertion [A] is True and Reason [R] is True but is not a correct explanation to [A].