1
MCQ (Single Correct Answer)

AIPMT 2009

The segment of DNA which acts as the instrumental manual for the synthesis of the protein is
A
ribose
B
gene
C
nucleoside
D
nucleotide

Explanation

The DNA sequence that codes for a specific protein is called a Gene and thus every protein in a cell has a corrosponding gene.
2
MCQ (Single Correct Answer)

AIPMT 2008

Which of the following is an amine hormone?
A
Insulin
B
Progesterone
C
Thyroxine
D
Oxypurin

Explanation

Thyroxine is an amino hormone.
3
MCQ (Single Correct Answer)

AIPMT 2008

In DNA, the complimentary bases are
A
adenine and guanine; thymine and cytosine
B
uracil and adenine; cytosine and guanine
C
adenine and thymine; guanine and cytosine
D
adenine and thymine; guanine and uracil.

Explanation

DNA contains two types of nitrogeneous bases

Purine $$ \to $$ Adenine (A) and guanine (G)

Pyrimidine $$ \to $$ Cytosine (C) and thymine (T)

The purine and pyrimidine bases pair only in certain combination. Adenine pairs with thymine (A : T) by two hydrogen bonds and guanine with cytosine (G : C) by three hydrogen bonds.
4
MCQ (Single Correct Answer)

AIPMT 2007

RNA and DNA are chiral molecules, their chirality is due to
A
chiral bases
B
chiral phosphate ester units
C
$$D$$-sugar component
D
$$L$$-sugar component

Explanation

Each nucleic acid consists of a pentose sugar a heterocyclic base, and phosphoric acid. The sugar present in DNA is -D (–) -2-deoxy ribose and the sugar present in RNA is D (–)- ribose. The chirality of DNA and RNA molecules are due to the presence of sugar components.

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