Question

The four elements that make up 99% of all elements found in a living system are

• A. C, H, O and P
• B. C, N, O and P
• C. H, O, C and N
• D. C, H, O and S.

Answer 1

The Correct Option is C

The question asks about the four elements that predominantly constitute the living systems. These elements must be the most abundant in biological organisms.

1. Breakdown of Options: The given options include:
   • C, H, O and P
   • C, N, O and P
   • H, O, C and N
   • C, H, O and S
2. Understanding the Elements: Let's examine the significance of each element in the context of living organisms.
   • Carbon (C): The backbone of organic molecules like carbohydrates, proteins, lipids, and nucleic acids.
   • Hydrogen (H): A key component of water (a major component of cells) and organic compounds.
   • Oxygen (O): Essential for cellular respiration and a component of water.
   • Nitrogen (N): A critical component of amino acids, proteins, and nucleic acids.
   • Phosphorus (P): Part of nucleic acids and ATP, but not as abundant as the first four elements.
   • Sulfur (S): Found in some amino acids but less abundant overall.
3. Analysis of Options:
   • C, H, O and P
     : While C, H, and O are certainly major components, P is not typically as abundant as N.
   • C, N, O and P
     : Again includes P, which is less abundant compared to H.
   • H, O, C and N
     : Includes all four of the most abundant elements, making this the most accurate choice.
   • C, H, O and S
     : S is less commonly abundant compared to N.
4. Conclusion: The correct answer is
   H, O, C and N
   , as these elements are the most prevalent in living organisms, accounting for about 99% of the body's elements.