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04/12/2025

Class 11 Biology
Chapter Biomolecules important MCQ

1. Which biomolecule is the primary source of energy in living organisms?
a) Proteins
b) Carbohydrates
c) Nucleic acids
d) Lipids
Answer: b) Carbohydrates

2. Which monosaccharide is known as "blood sugar"?
a) Glucose
b) Fructose
c) Galactose
d) Sucrose
Answer: a) Glucose

3. Enzymes, antibodies, and hormones are examples of:
a) Carbohydrates
b) Proteins
c) Lipids
d) Nucleic acids
Answer: b) Proteins

4. The building blocks of proteins are:
a) Nucleotides
b) Amino acids
c) Monosaccharides
d) Fatty acids
Answer: b) Amino acids

5. Which biomolecule stores genetic information and directs cellular activities?
a) Carbohydrates
b) Proteins
c) Lipids
d) Nucleic acids
Answer: d) Nucleic acids

6. Which of the following is a polysaccharide used for energy storage in plants?
a) Cellulose
b) Glycogen
c) Starch
d) Chitin
Answer: c) Starch

7. Feedback inhibition of enzymes is affected by which of the following?
a) Enzyme
b) Substrate
c) End products
d) Intermediate end products
Answer: c) End products

8. An example of competitive inhibition of an enzyme is the inhibition of:
a) Succinic dehydrogenase by malonic acid
b) Cytochrome oxidase by cyanide
c) Hexokinase by glucose-6-phosphate
d) Carbonic anhydrase by carbon dioxide
Answer: a) Succinic dehydrogenase by malonic acid

9. Which biomolecule is not involved in energy storage?
a) ATP
b) Glycogen
c) Cellulose
d) Starch
Answer: c) Cellulose

10. Which of the following is an example of a disaccharide?
a) Glucose
b) Fructose
c) Sucrose
d) Galactose
Answer: c) Sucrose

11. Which biomolecule plays a structural role in plant cell walls?
a) Chitin
b) Cellulose
c) Glycogen
d) Amylose
Answer: b) Cellulose

12. Which vitamin is synthesized by intestinal bacteria?
a) Vitamin C
b) Vitamin K
c) Vitamin A
d) Vitamin D
Answer: b) Vitamin K

13. Which of the following macromolecules can act as both structural and catalytic components in living systems?
a) Lipids
b) Carbohydrates
c) Proteins
d) Nucleic acids
Answer: c) Proteins

14. Which one of these lipids acts as a precursor for steroid hormones?
a) Triglyceride
b) Cholesterol
c) Glycolipid
d) Phospholipid
Answer: b) Cholesterol

15. Denaturation of proteins affects which structural level first?
a) Primary
b) Secondary
c) Tertiary
d) Quaternary
Answer: c) Tertiary

16. Which compound is used to detect the presence of starch?
a) Benedict's reagent
b) Biuret reagent
c) Iodine solution
d) Sudan III
Answer: c) Iodine solution

17. Which property makes water essential in biochemical reactions?
a) High density
b) Low viscosity
c) Solvent nature
d) Non-polarity
Answer: c) Solvent nature

18. Which of the following is a conjugated protein?
a) Albumin
b) Pepsin
c) Haemoglobin
d) Insulin
Answer: c) Haemoglobin

19. Which method is commonly used for protein separation based on molecular size?
a) Electrophoresis
b) Chromatography
c) Centrifugation
d) Dialysis
Answer: a) Electrophoresis

20. Which class of enzymes catalyzes oxidation-reduction reactions?
a) Transferases
b) Oxidoreductases
c) Hydrolases
d) Ligases
Answer: b) Oxidoreductases