MCQ Detailed View

Phosphorus is a crucial chemical element for all living organisms, playing a key role in the structure and function of cells. Among biological macromolecules, phosphorus is an essential component of nucleic acids, specifically DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). These molecules store and transmit genetic information in every living cell.

Nucleic acids are composed of nucleotides, and each nucleotide contains three parts:

1. 
   

   A nitrogenous base (adenine, thymine/uracil, cytosine, or guanine),

   
   


2. 
   

   A sugar molecule (deoxyribose in DNA, ribose in RNA),

   
   


3. 
   

   A phosphate group, which contains phosphorus atoms.

   
   

The phosphate groups form strong bonds linking one nucleotide to another, creating the sugar-phosphate backbone of nucleic acid chains. Without phosphorus, these molecules could not maintain their structure or carry genetic information effectively.

Other options are incorrect:

• 
  

  Amino acids: The building blocks of proteins mainly contain carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur, but not phosphorus.

  
  


• 
  

  Carbohydrates: These consist of carbon, hydrogen, and oxygen only, with no phosphorus in their basic structure.

  
  

Phosphorus is also vital for energy transfer within cells, being part of ATP (adenosine triphosphate), the primary energy currency of life. It is found in cell membranes as phospholipids, making it indispensable for cell function and reproduction.

Therefore, the correct answer is Nucleic acids (Option B), as phosphorus is a fundamental element in their molecular structure and is essential for the storage and expression of genetic information.