Question

Which base is normally found in RNA but not in DNA?
A. Uracil
B. Thymine
C. Guanine
D. Adenine

Answer 1

Hint: We know that there are two types of nucleic acids, DNA and RNA. The full form of DNA is Deoxyribo nucleic acid and full form of RNA is ribonucleic acid.

Complete step by step answer:
We know that there are four bases in DNA. They are, adenine (A), Guanine (G), cytosine (C) and Thymine (T). And there are also four bases in RNA. Out of the four bases, three are common with the base of DNA, they are, adenine (A), Guanine (G) and Cytosine (C). One uncommon base present in RNA is uracil.

So, the correct option is A, that is, uracil.

Additional information:

RNA	DNA
1) It consists of single stranded structure (exception to some virus)	1) It consists of double stranded structure (exception to some virus)
2) Have ribose sugar	2) Have deoxyribose sugar
3) The pairing of adenine and uracil in RNA	3) The pairing of adenine and thymine in DNA
4) It is genetic material to some viruses	4) It is genetic material in all living organisms
5) It occurs in the form of three types in an organism, mRNA, rRNA and tRNA	5) Only one form is present in an organism
6) Its length is short comprising few thousands nucleotides	6) Its length is quite large comprising millions of nucleotides

Note:
DNA consists of two strands which are wind around each other like that of a twisted ladder. Each strand of DNA has backbone made of sugar and phosphate groups. Each sugar is attached to four bases, adenine, guanine, thymine and cytosine. The hydrogen bonding between bases of two strands holds the two strands. The adenine forms base pairs with thymine and cytosine forms base pairs with guanine.