Biomolecules — Class 12 Chemistry PYQs

Two among the three components of DNA are β-D-2-deoxyribose and a heterocyclic base. The third component is :
(A) Adenine
(B) Phosphoric acid
(C) Sulphuric acid
(D) Uracil

Maltose is made up of :
(A) glucose and fructose
(B) glucose and galactose
(C) glucose and glucose
(D) glucose and ribose

Nucleotides are composed of a :
(A) pentose sugar and phosphoric acid
(B) nitrogenous base, pentose sugar and phosphoric acid
(C) nitrogenous base and phosphoric acid
(D) pentose sugar and nitrogenous base

Which functional groups of glucose interact to form cyclic hemiacetal leading to pyranose structure ?
(A) Aldehyde group and hydroxyl group at C – 4
(B) Aldehyde group and hydroxyl group at C – 5
(C) Ketone group and hydroxyl group at C – 4
(D) Ketone group and hydroxyl group at C – 5

All proteins on hydrolysis give :
(A) Enzymes
(B) α-amino acids
(C) Glucose
(D) Polypeptides

The specific sequence in which amino acids are arranged in a protein is called :
(A) Secondary structure
(B) Primary structure
(C) Tertiary structure
(D) Quaternary structure

Assertion (A) : Uracil base is present in RNA.
Reason (R) : RNA undergoes self-replication.
(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
(C) Assertion (A) is true, but Reason (R) is false.
(D) Assertion (A) is false, but Reason (R) is true.

Assertion (A) : Uracil base is present in DNA.
Reason (R) : DNA undergoes self-replication.
(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
(C) Assertion (A) is true, but Reason (R) is false.
(D) Assertion (A) is false, but Reason (R) is true.

Assertion (A) : Vitamin C cannot be stored in our body.
Reason (R) : Vitamin C is water soluble and readily excreted in urine.
(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
(C) Assertion (A) is true, but Reason (R) is false.
(D) Assertion (A) is false, but Reason (R) is true.

Define the following terms :
(a) Essential amino acids
(b) Nucleotide