Class 11 Biology (NCERT / JAC Board)

1. Which compound is used for chemical analysis of living tissues to separate acid-soluble and acid-insoluble fractions?

• A. Trichloroacetic acid (CCl3COOH)
• B. Hydrochloric acid (HCl)
• C. Acetic acid (CH3COOH)
• D. Sulphuric acid (H2SO4)

2. Lipids are found in the acid-insoluble fraction despite having a low molecular weight because they:

• A. Form membrane vesicles that do not pass through filters
• B. Are giant polymeric networks
• C. Are strictly macro-biomolecules
• D. Covalently bond directly to proteins

3. Amino acids are termed substituted methanes because four substituent groups occupy the four valency positions of the:

• A. Alpha-carbon
• B. Beta-carbon
• C. Carboxyl carbon
• D. Amino nitrogen

4. Which bond links individual amino acid monomers together to form a polypeptide chain?

• A. Peptide bond
• B. Glycosidic bond
• C. Phosphodiester bond
• D. Hydrogen bond

5. Starch gives a characteristic blue color with iodine because:

• A. Helical secondary structures of starch trap iodine molecules
• B. Iodine oxidizes starch to glucose
• C. Starch is a reducing disaccharide
• D. Cellulose and starch form complex coacervates

6. What type of bond connects adjacent nucleotides along a single strand of nucleic acid?

• A. 3'-5' Phosphodiester bond
• B. Peptide bond
• C. Glycosidic bond
• D. Ester bond

7. The primary protein structure represents:

• A. The linear sequence of amino acids in a polypeptide chain
• B. Local folding into alpha-helices or beta-pleated sheets
• C. Three-dimensional folding into a functional active unit
• D. Multi-subunit quaternary protein complexes

8. The most abundant protein in the whole of the biosphere is:

• A. RuBisCO
• B. Collagen
• C. Insulin
• D. Hemoglobin

9. Enzymes increase reaction rates by lowering which energy barrier?

• A. Activation energy
• B. Free energy of reactants
• C. Kinetic energy of products
• D. Potential energy of substrate

10. Inhibition of succinic dehydrogenase by malonate due to structural similarity with succinate is an example of:

• A. Competitive inhibition
• B. Non-competitive inhibition
• C. Allosteric feedback regulation
• D. Irreversible denaturation

11. Which of the following is an essential aromatic amino acid?

• A. Phenylalanine
• B. Glycine
• C. Alanine
• D. Valine

12. Lecithin is a nitrogenous phospholipid commonly found in cell membranes. It belongs to which class of lipids?

• A. Phospholipids
• B. Simple fats
• C. Steroids
• D. Waxes

13. The simplest amino acid which lacks a chiral carbon center (optically inactive) is:

• A. Glycine
• B. Alanine
• C. Serine
• D. Glutamic acid

14. The chemical bond present between sugar and nitrogenous base in a nucleoside is:

• A. N-glycosidic bond
• B. Phosphoester bond
• C. Peptide bond
• D. Hydrogen bond

15. Glycogen, the storage polysaccharide in animals, is a branched polymer of:

• A. Glucose
• B. Fructose
• C. Galactose
• D. Ribose

16. Non-protein constituent organic component tightly bound to the apoenzyme to make it catalytically active is called a:

• A. Prosthetic group
• B. Coenzyme
• C. Metal ion activator
• D. Isoenzyme

17. Which purine nitrogenous bases are present in both DNA and RNA?

• A. Adenine and Guanine
• B. Cytosine and Thymine
• C. Adenine and Uracil
• D. Guanine and Cytosine

18. The exoskeleton of arthropods and fungal cell walls are composed of a complex polysaccharide named:

• A. Chitin
• B. Cellulose
• C. Peptidoglycan
• D. Pectin

19. Zinc acts as a co-factor for which catalytic enzyme?

• A. Carboxypeptidase
• B. Catalase
• C. Peroxidase
• D. Dehydrogenase

20. In B-DNA double helix structure, the pitch of the helix per turn is:

• A. 3.4 nm (34 Å)
• B. 0.34 nm (3.4 Å)
• C. 2.0 nm (20 Å)
• D. 34 nm (340 Å)

21. Secondary metabolites that act as toxins include:

• A. Abrin and Ricin
• B. Morphine and Codeine
• C. Concanavalin A
• D. Vinblastine and Curcumin

22. Concanavalin A belongs to which group of plant secondary metabolites?

• A. Lectins
• B. Alkaloids
• C. Essential oils
• D. Polymeric substances

23. Saturated fatty acids differ from unsaturated fatty acids in having:

• A. Only single carbon-carbon bonds in their hydrocarbon chain
• B. One or more double bonds (-C=C-)
• C. Ring structures with double bonds
• D. Esterified glycerol groups

24. Total number of carbon atoms present in palmitic acid including the carboxyl carbon is:

• A. 16
• B. 20
• C. 18
• D. 15

25. Isoenzymes are enzymes that:

• A. Differ in amino acid sequence but catalyze the same chemical reaction
• B. Have identical primary structures but different substrates
• C. Require identical non-protein cofactors
• D. Function only at sub-zero temperatures