Question

DNA has 2deoxyribose, base and a third component known as-
A. Ribose
B. Adenine
C. Phosphoric acid
D. Guanine

Answer 1

Hint: As we know, DNA is the genetic material in all organisms. It is the largest biomolecule. DNA occurs in the cytoplasm and confines to the nucleus as a component of the chromosome. This is nuclear DNA.

Complete answer:
DNA is a long chain of deoxyribonucleotide units. The two chains of deoxyribonucleotide are twisted around each other onto a common axis to give rise to a right handed double-helix. DNA consists of a phosphoric acid which is basically a phosphate group, a nitrogenous base that consists of adenine, guanine, thymine, cytosine and a sugar that joins the bases in the nucleotide. The phosphoric acid present at the 5’ position of the carbon atom and joined to the hydroxyl component present at the 3’ position carbon atom by a phosphodiester bond. This phosphodiester bond provides stability to the structure.

Hence the correct option is option C i.e phosphoric acid.

Additional information: Watson and Crick gave a model on DNA to explain its structure. DNA follows the complementarity of base pairs i.e adenine in one chain must be attached to thymine if the other chain, guanine should be opposite to the cytosine. The two chains of DNA are complementary to each other with the concept of specific base pairing. The base pairs further one in each chain of DNA molecules joined by the Hydrogen bond.

Note:
The DNA content in the cell is constant in every species but just before cell division, the DNA amount is doubled. The gametes usually have half the amount of DNA present due to the presence of half amount of chromosome.