Question

Given below are two statements:

Statement I: Low temperature preserves the enzyme in a temporarily inactive state whereas high temperature destroys enzymatic activity because proteins are denatured by heat.
Statement II: When the inhibitor closely resembles the substrate in its molecular structure and inhibits the activity of the enzyme, it is known as competitive inhibitor.

In the light of the above statements, choose the correct answer from the options given below:

• A. Both Statement I and Statement II are false.
• B. Statement I is true but Statement II is false.
• C. Statement I is false but Statement II is true
• D. Both Statement I and Statement II are true.

Answer 1

The Correct Option is D

To verify the two statements, let us analyze each one based on biological principles.

Statement I: It asserts that low temperature keeps an enzyme inactive while high temperature denatures enzyme proteins, thereby destroying their activity. Enzymes are proteins which can be affected by temperature changes. At low temperatures, enzyme activity is reduced because molecules move slower and have less kinetic energy, temporarily inactivating the enzyme. Conversely, at high temperatures, the heat causes the enzymes to denature, altering their structure and rendering them nonfunctional. Therefore, Statement I is true.

Statement II: It posits that when an inhibitor resembles the substrate's molecular structure and inhibits enzyme activity, it is known as a competitive inhibitor. Competitive inhibitors compete with the substrate for the active site of the enzyme because of their structural similarity. This type of inhibition can be overcome by increasing substrate concentration. Hence, Statement II is also true.

Conclusion: Based on the analysis, both statements are true.

Answer 2

Statement I is true - Low temperatures can slow down enzymatic reactions by placing the enzyme in an inactive state, and high temperatures can denature proteins, including enzymes, which can lead to a loss of enzymatic activity.

Statement II is also true - A competitive inhibitor is a molecule that closely resembles the substrate of an enzyme and competes for the active site, thus reducing the enzyme's activity. This type of inhibition is called competitive inhibition.

So, the correct option is (D): Both Statement I and Statement II are true.