UPSC CSE Prelims
Question 71
Consider the following minerals:
- Calcium
- Iron
- Sodium
Which of the minerals given above is/are required by human body for the contraction of muscles?
View correct answer and explanation
Correct answer: D
Correct Option: D
Explanation: Calcium triggers contraction, sodium ions enable electrical excitation and iron supports oxygen delivery and muscle proteins, so the supplied key treats all three as required for muscle function.
Statement/Pair-wise Analysis:
Statement/Item 1: Correct - Calcium ions directly regulate actin–myosin contraction via troponin.
Statement/Item 2: Correct - Iron is essential for myoglobin and oxygen-dependent muscle metabolism, although it is not the immediate trigger for contraction.
Statement/Item 3: Correct - Sodium is needed for nerve and muscle action potentials that initiate contraction.
Option-wise Analysis:
A: Incorrect - excludes true items 2, 3.
B: Incorrect - excludes true item 1.
C: Incorrect - excludes true item 2.
D: Correct - selects all and only the accurate statements/pairs.
Review Note: Iron supports muscle function indirectly; strictly the immediate contraction machinery principally involves Ca²⁺ and ATP, with Na⁺ involved in excitation. The answer D uses a broad nutritional reading of “required”.