Multiple choice

Which of the following are the most abundant elements in the living cells?

  1. C, H, S and P

  2. C, O, N and P

  3. C, H, O and N

  4. C, H, Mg and Ca
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Carbon, hydrogen, oxygen, and nitrogen constitute approximately 99% of living matter by mass. Carbon forms the backbone of organic molecules, hydrogen and oxygen are abundant in water and organic compounds, and nitrogen is essential for proteins and nucleic acids. Sulfur and phosphorus, while important, are present in much smaller quantities than these four.

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