What are the six elements that make up 99% of all elements found in a living system?
Correct answer: C. H, O, C, N, Ca and P
- A. C, H, O, P, Mg and Fe
- B. C, N, O, P, Mn and Cl
- C. H, O, C, N, Ca and P
- D. C, H, O, S, Fe, Ca
Explanation
Carbon, hydrogen, oxygen, and nitrogen are called the four big elements of the living body as they make up about 99% of the mass of most cells. As C, H, O, and N are the lightest elements, the bonds they form are the strongest covalent bonds.Hence, the compounds formed are stable and variable in size and shape. Carbon constitutes more than 50% of the dry matter while it has been observed that the human body contains 0.5% hydrogen, 18.5% carbon, 65% oxygen, and 3.3% nitrogen. Other elements are present in a lesser amount.
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The chapter covers water's polarity and biological roles, carbohydrates, lipids, proteins and nucleic acids, including their monomers, bonds, structures and functions. It also distinguishes RNA from DNA and explains conjugated molecules such as glycoproteins, glycolipids and nucleoproteins, which combine organic molecules with a non-protein component.
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