UPSC CAPF (AC) 2026 Paper I · Question 99

Question 99 of the UPSC CAPF (AC) 2026 Paper I (19 July 2026). Try it first, then open the answer and explanation.

1. CAPF 2026 · P-I · Q99 · General Science · Biology

   Which one of the following is considered as the basic structural element of all life forms?

   1. Phosphorus
   2. Carbon
   3. Oxygen
   4. Nitrogen

   निम्नलिखित में से किसे सभी जीव रूपों के मूल संरचनात्मक तत्त्व के रूप में माना जाता है?

   1. फॉस्फोरस
   2. कार्बन
   3. ऑक्सीजन
   4. नाइट्रोजन
   Show answer

   Answer: (2) Carbon

   उत्तर: (2) कार्बन

   Carbon is tetravalent and can bond with itself to form long chains and rings (catenation), so it forms the backbone of all biomolecules such as carbohydrates, proteins, lipids and nucleic acids; that is why life is called carbon-based. Oxygen is the most abundant element by mass in the body, but it is carbon that provides the structural framework.

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