250+ TOP MCQs on Biomolecules-2 and Answers

Biology Multiple Choice Questions on “Biomolecules-2”.

1. 20 amino acids undergo different permutations and combinations to form a large number of proteins.
a) True
b) False
Answer: a
Clarification: 20 amino acids undergo different permutations and combinations to form a large number of proteins. Proteins are biomacromolecules that function as enzymes, defense compounds and help to maintain structure.

2. Which among the following is incorrect about amino acids?
a) Amino acids are those that contain an amine group and a carboxylic group
b) Base on the position of amino group with respect to the carboxylic group, amino groups are classified as α-, β-, γ-, δ- amino acids
c) Proteins on hydrolysis produce α-, β-, γ-, δ- amino acids
d) Amino acids are usually represented by a three letter symbol or a one letter convention
Answer: c
Clarification: Amino acids are those that contain an amine group and a carboxylic group. Base on the position of amino group with respect to the carboxylic group, amino groups are classified as α-, β-, γ-, δ- amino acids. Proteins on hydrolysis produce only α-amino acids.

3. Which among the following is incorrect about amino acids?
a) There are 20 naturally occurring amino acids
b) All the amino acids are chiral
c) Amino acids are classified as acidic, basic or neutral based on the relative number of amino and carboxylic groups
d) Amino acids are classified as essential amino acids and non-essential based on whether they are synthesized in the body or not
Answer: b
Clarification: There are 20 naturally occurring amino acids. All the amino acids except glycine are chiral. Amino acids are classified as acidic, basic or neutral based on the relative number of amino and carboxylic groups. Amino acids are classified as essential amino acids and non-essential based on whether they are synthesized in the body or not.

4. Zwitter ion in aqueous solution is __________
a) Amphoteric
b) Acidic
c) Basic
d) Anomalous
Answer: d
Clarification: Zwitter ion is formed when an amino acid is present in an aqueous solution. In an aqueous solution, –COOH looses hydrogen ion whereas –NH₂ gains hydrogen to form –COO^– and –NH₃+. It is amphoteric in an aqueous solution.

5. Non-essential amino acids are those amino acids that our body doesn’t contain and acquires it through food.
a) True
b) False
Answer: b
Clarification: Non-essential amino acids are those amino acids that are present in our body already and need not be taken through food. Essential amino acids are those amino acids that our body fails to synthesize and have taken through diet.

6. Proteins are polymers of amino acids that are connected by __________
a) Peptide linkage
b) Glycosidic linkage
c) Phosphodiester linkage
d) Vanderwaal linkages
Answer: a
Clarification: Proteins are polymers of amino acids undergo dehydration to form a peptide linkage. Dipeptides are formed by a single peptide bond and a tripeptide through two peptide bonds and so on.

7. Which among the following statements is incorrect about classification of protein?
a) Fibrous proteins result when long peptide chains run parallel and are held by hydrogen and sulphide linkages
b) Globular structures result when chain of polypeptide coil around themselves to form a globe like structure
c) Linear structure of amino acids in a polypeptide is called primary structure
d) Collagen is an example of globular protein
Answer: d
Clarification: Fibrous proteins result when long peptide chains run parallel and are held by hydrogen and sulphide linkages. Globular structures result when chain of polypeptide coil around themselves to form a globe like structure. Linear structure of amino acids in a polypeptide is called primary structure. Collagen is an example of fibrous protein.

8. Tertiary structure of protein is formed by __________
a) Sulphide linkages between different amino acids
b) Multiple chains of polypeptides held together by hydrogen bonds
c) Peptide linkages between two amino acids
d) Hydrogen bond formed by helical or pleated structure
Answer: a
Clarification: Primary structure of protein is formed by peptide linkages between two amino acids. Secondary structure, i.e. α-Helix and β-Sheath, of protein is formed by hydrogen bonds. Tertiary structure of protein is formed by sulphide linkages between different amino acids Quaternary structure is formed when multiple chains of polypeptides held together by hydrogen bonds.

9. Which among the following is incorrect about denaturation?
a) Proteins have a unique structure which might get disrupted with change in pH and temperature
b) Secondary, tertiary and quaternary structure is lost
c) Proteins still retain their characteristics as they don’t lose their primary structure
d) Proteins are stereospecific to many enzymes
Answer: c
Clarification: Proteins have a unique structure which might get disrupted with change in pH and temperature. Denaturation leads to loss of secondary, tertiary and quaternary structure. Proteins lose their characteristic if their structure is lost. Proteins are stereospecific to many enzymes.

10. Which among the following is incorrect about enzymes?
a) Enzymes are proteins or non-proteins that act as bio-catalysts
b) Holoenzymes comprise of a prosthetic group and an apoenzyme
c) Prosthetic group can be either co-factors or co-enzymes
d) Cutting a potato leads to the breakage of bonds in the enzymes present in it
Answer: d
Clarification: Enzymes are proteins or non-proteins that act as bio-catalysts. Holoenzymes comprise of a prosthetic group and an apoenzyme. Prosthetic group can be either co-factors or co-enzymes. Cutting a potato is a physical change and doesn’t lead to the breakage of bonds in the enzymes present in it.