Biology – Proteins MCQ

Proteins are fundamental building blocks of life, essential for numerous functions such as building and repairing tissues, supporting immune functions, and acting as enzymes. Test your knowldge of proteins through these beginner-friendly multiple-choice questions.

1. Which of the following is the basic building block of proteins?

a) Nucleotide
b) Amino acid
c) Fatty acid
d) Saccharide

Answer:

b) Amino acid

Explanation:

Proteins are made up of amino acids, which are their basic building blocks.

2. How many standard amino acids are there in proteins?

a) 20
b) 10
c) 25
d) 30

Answer:

a) 20

Explanation:

There are 20 standard amino acids that form the basic building blocks of proteins.

3. Which protein structure is determined by the sequence of amino acids?

a) Primary
b) Secondary
c) Tertiary
d) Quaternary

Answer:

a) Primary

Explanation:

The primary structure of a protein is determined by the sequence of amino acids.

4. Which of the following proteins carries oxygen in the blood?

a) Hemoglobin
b) Insulin
c) Collagen
d) Myosin

Answer:

a) Hemoglobin

Explanation:

Hemoglobin is the protein in red blood cells that carries oxygen from the lungs to the rest of the body.

5. Enzymes are primarily made of which type of organic compound?

a) Lipids
b) Carbohydrates
c) Proteins
d) Nucleic acids

Answer:

c) Proteins

Explanation:

Enzymes are primarily proteins that act as biological catalysts to accelerate chemical reactions.

6. What level of protein structure is represented by the folding of a protein into a 3D shape?

a) Primary
b) Secondary
c) Tertiary
d) Quaternary

Answer:

c) Tertiary

Explanation:

The tertiary structure of a protein is its three-dimensional shape, resulting from the folding of the polypeptide chain.

7. Which of the following proteins is a major component of hair and nails?

a) Keratin
b) Collagen
c) Actin
d) Albumin

Answer:

a) Keratin

Explanation:

Keratin is a structural protein that is a major component of hair, nails, and the outer layer of skin.

8. What is the function of antibodies?

a) Oxygen transport
b) Muscle contraction
c) Immune defense
d) Enzymatic reaction

Answer:

c) Immune defense

Explanation:

Antibodies are proteins produced by the immune system to help neutralize pathogens such as bacteria and viruses.

9. Which of the following is a protein that acts as a hormone?

a) Insulin
b) Hemoglobin
c) Collagen
d) Keratin

Answer:

a) Insulin

Explanation:

Insulin is a hormone protein that regulates glucose levels in the blood.

10. What causes a protein to denature?

a) Freezing
b) Change in pH or temperature
c) Absorption of light
d) Dissolving in water

Answer:

b) Change in pH or temperature

Explanation:

Proteins can denature, or lose their structure and function, due to changes in temperature or pH.

11. What type of bond holds amino acids together in a protein?

a) Hydrogen bond
b) Ionic bond
c) Peptide bond
d) Covalent bond

Answer:

c) Peptide bond

Explanation:

Amino acids are joined together by peptide bonds to form proteins.

12. Which protein is responsible for muscle contraction?

a) Myosin
b) Keratin
c) Hemoglobin
d) Antibody

Answer:

a) Myosin

Explanation:

Myosin is a motor protein that plays a key role in muscle contraction.

13. Which of the following is not a function of proteins?

a) Energy storage
b) Structural support
c) Transport of oxygen
d) Information storage

Answer:

d) Information storage

Explanation:

Proteins perform a wide range of functions, but information storage is primarily the role of nucleic acids like DNA and RNA.

14. What protein structure is formed by the interaction of multiple polypeptide chains?

a) Primary
b) Secondary
c) Tertiary
d) Quaternary

Answer:

d) Quaternary

Explanation:

Quaternary structure is formed by the interaction of multiple polypeptide chains in a protein.

15. Which of the following is a fibrous protein?

a) Enzyme
b) Hemoglobin
c) Collagen
d) Insulin

Answer:

c) Collagen

Explanation:

Collagen is a fibrous protein that provides structure and support to tissues like skin, tendons, and ligaments.


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