250+ TOP MCQs on Biomolecules – Proteins and Answers

Biology Multiple Choice Questions on “Biomolecules – Proteins”.

1. What is the full form of RuBisCO?
a) Ribosome bisphosphate Carboxylase-Oxidase
b) Ribulose bisphosphate Carboxylase-Oxidase
c) Ribosome bisphosphate Carboxy-Oxygenase
d) Ribulose bisphosphate Carboxylase-Oxygenase
Answer: d
Clarification: The full form of RuBisCO is Ribulose bisphosphate Carboxylase-Oxygenase. It is an important enzyme found in plants that plays a major role in photosynthesis. It catalyzes the first major step of carbon fixation.

2. Which protein is the most abundant?
a) ATP synthase
b) Collagen
c) RuBisCO
d) NADPH oxidase
Answer: c
Clarification: RuBisCO or Ribulose bisphosphate Carboxylase-Oxygenase is the most abundant protein in the biosphere. It is an important enzyme required in photosynthesis to catalyze the first major step of carbon fixation.

3. Which protein is most abundant in the animal world?
a) Actin
b) Keratin
c) Collagen
d) Histone
Answer: c
Clarification: Collagen is the most abundant protein of the animal world. It is the main structural protein in the extracellular matrix in the connective tissues. Collagen forms a scaffold to provide strength and structure to the entire body.

4. Which of these is not a function of protein?
a) Major constituent of the cell membrane
b) Transport of nutrients
c) Defense against pathogens
d) Regulation of homeostasis
Answer: a
Clarification: Proteins have numerous important functions in the body. They help to transport nutrients across cells and through blood. They make up the immune system and maintain homeostasis. However, lipids are the major constituent of the cell membrane.

5. How are essential amino acids obtained?
a) Produced in the body
b) Through diet
c) Its levels remain constant
d) From plants
Answer: b
Clarification: Amino acids can be divided into two groups- essential amino acids and non-essential amino acids. Non-essential amino acids are produced by the body while essential amino acids are obtained through our diet.

6. A protein is a _____
a) monomer
b) homopolymer
c) heteropolymer
d) dimer
Answer: c
Clarification: Proteins are heteropolymers of amino acids. This means that out of the 20 amino acids, various combinations of the amino acids may result in the formation of a protein. This protein may be functional or non-functional.

7. Amino acids are linked together by _____
a) peptide bonds
b) hydrogen bonds
c) glycosidic linkages
d) hydrophobic interactions
Answer: a
Clarification: Amino acids are linked to each other by the formation of peptide bonds between the acidic group of one amino acid and the amino group of the other amino acid with the release of one water molecule.

8. A continuous strand of the same amino acids linked to each other forms a _____
a) dimer
b) monomer
c) heteropolymer
d) homopolymer
Answer: d
Clarification: A homopolymer is a repeated sequence of the same monomer multiple number of times. Heteropolymers are made of different monomers. For example, proteins are heteropolymers of various amino acids.

9. Collagen is a(n) ______
a) hormone
b) intracellular ground substance
c) intercellular ground substance
d) enzyme
Answer: c
Clarification: Collagen is an intercellular ground substance. It is a major structural protein found in the extracellular matrix of the various connective tissues found in the body. It is the most abundant protein in the animal world.

10. Dietary proteins are the source of non-essential amino acids. True or false?
a) True
b) False
Answer: b
Clarification: Non-essential amino acids are those which can be produced in the body, so it is not necessary to obtain them from the diet. Dietary proteins are the source for essential amino acids which cannot be produced in the body.

11. Which of these is an enzyme?
a) GLUT-4
b) Collagen
c) Insulin
d) Trypsin
Answer: d
Clarification: Trypsin is an enzyme that helps in protein digestion in the small intestine. Collagen is a structural protein; insulin is a hormone and GLUT-4 is a carrier protein that enables the transport of glucose into the cell.

12. Which of these is a hormone?
a) Collagen
b) Keratin
c) Insulin
d) GLUT-4
Answer: c
Clarification: Keratin and collagen are structural proteins found in the body. GLUT-4 is a carrier protein that enables the transport of glucose into the cells. Insulin is a hormone that regulates the blood glucose level.

13. What is the function of antibody?
a) Acts as tissue toxins
b) Degrades old erythrocytes
c) Fights infectious agents
d) Helps in growth of cells
Answer: c
Clarification: Antibodies or immunoglobulins are proteins that play a major role in the immune response of our body. They are Y-shaped proteins present in blood plasma that help fight various pathogens and infectious agents.

14. Which of these proteins help in recognition of sensory signals?
a) Receptor proteins
b) Structural proteins
c) Hormones
d) Nucleoproteins
Answer: a
Clarification: Receptor proteins help to recognize various sensory signals such as smell and taste. Receptor proteins present on and inside cells recognize various hormones and compounds required for the normal functioning of the cell.

15. What is the function of GLUT-4?
a) Enables transport of both insulin and glucose into cells
b) Enables glucose transport into cells
c) Enables glucose transport out of cells
d) Enables transport of both sodium and glucose out of cells
Answer: b
Clarification: GLUT-4 is a carrier protein. It is an insulin-regulated glucose transporter. The function of GLUT-4 is to enable the transport of glucose molecules into the cells through a series or cascade of reactions.