Question

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Cells of different tissues essentially require CO\(_2\) to generate energy and perform metabolic functions.
Reason (R) : Deficiency of oxygen or hypoxia results in failure to carry metabolic functions.
In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
• C. (A) is correct but (R) is not correct
• D. (A) is not correct but (R) is correct

Hint:

Always carefully read Assertion statements for swapped biological terms. Here, substituting the requirement of O\(_2\) with the waste product CO\(_2\) instantly makes the statement factually incorrect.

Answer 1

The Correct Option is D

Step 1: Concept:
This question evaluates the fundamental biochemical requirements for aerobic cellular respiration and energy (ATP) generation within human tissue cells.

Step 2: Step-by-step Explanation:

• Analyzing Assertion (A): The assertion claims that cells essentially require carbon dioxide (CO\(_2\)) to generate energy. This is a biologically inaccurate statement for mammalian cells. Human tissue cells absolutely require oxygen (O\(_2\)) for aerobic cellular respiration to generate ATP. Carbon dioxide is actually a metabolic waste byproduct produced during the Krebs cycle, which must be expelled from the body. Therefore, Assertion (A) is false.

• Analyzing Reason (R): The reason states that a deficiency of oxygen, clinically termed hypoxia, leads to a failure in carrying out metabolic functions. This is completely true. Oxygen serves as the final electron acceptor in the mitochondrial electron transport chain (ETC).

• Without oxygen, the ETC halts, a proton gradient cannot be maintained, and oxidative phosphorylation ceases. This forces the cell into inefficient anaerobic glycolysis, rapidly depleting ATP and ultimately causing cellular metabolic failure and death.

• Since Assertion (A) is false and Reason (R) is true, the correct logical relationship is identified.

Step 3: Final Answer:
Option (D) correctly identifies that (A) is not correct but (R) is correct.