NEET Previous Year Questions (2016-22): Biomolecules - Notes | Study Biology Class 11 - NEET

Q.1. Read the following statements on lipids and find out correct set of statements:  (2022)
(A) Lecithin found in the plasma membrane is a glycolipid
(B) Saturated fatty acids possess one or more c = c bonds
(C) Gingely oil has lower melting point, hence remains as oil in winter
(D) Lipids are generally insoluble in water but soluble in some organic solvents
(E) When fatty acid is esterified with gIycerol, monoglycerides are formed
Choose the correct answer from the options given below:
(a) (A), (D) and (E) only
(b) (C), (D) and (E) only
(c) (A), (B) and (D) only
(d) (A), (B) and (C) only
Ans. (b)
Solution. (i) Lecithin found in plasma membrane is a phospholipid not glycolipid.
(ii) Saturated fatty acids do not possess c = c bonds.

Q.2. A dehydration reaction links two glucose molecules to produce maltose. If the formula for glucose is C₆H₁₂O₆ then what is the formula for maltose?  (2022)
(a)C₁₂H₂₄O₁₂
(b)C₁₂H₂₂O₁₁
(c)C₁₂H₂₄O₁₁
(d)C₁₂H₂₀O₁₀
Ans. (b)
Solution. Maltose is a common disaccharide that is formed by the dehydration reaction of two glucose molecules. The glycosidic bond present in maltose is α − 1, 4. During the formation, from two glucose molecules, one molecule of water is removed. Thus, the formula of maltose becomes C₁₂H₂₂O₁₁

Q.3. Statements related to human Insulin are given below: Which statement(s) is/are correct about genetically engineered Insulin?  (2022)
(A) Pro-hormone insulin contain extra stretch of C-peptide.
(B) A-peptide and B-peptide chains of insulin were produced separately in E. coli, extracted and combined by creating disulphide bond between them.
(C) Insulin used for treating Diabetes was extracted from cattle and pigs.
(D) Pro-hormone Insulin needs to be processed for converting into a mature and functional hormone.
(e) Some patients develop allergic reactions to the foreign insulin.
Choose the most appropriate answer from the options given below.
(a) (B) only
(b) (C) and (D) only
(c) (C), (D) and (E) only
(d) (A), (B) and (D) only
Ans. (a)
Solution. In the year 1983, the American company Eli Lilly prepared two DNA sequences corresponding to A and B, chains of human insulin and introduced them in plasmids of E. coli to produce insulin chains. Chains A and B were produced separately, extracted and combined by creating disulfide bonds to form human insulin.

Q.4. Match List-I with List-II  (2022)

Choose the correct answer from the options given below:
(A) (a) - (iv), (b) - (ii), (c) - (i), (d) - (iii)
(B) (a) - (ii), (b) - (iv), (c) - (iii), (ii) - (i)
(C) (a) - (iv), (b) - (iii), (c) - (i), (d) - (ii)
(D) (a) - (iii), (b) - (ii), (c) - (iv), (d) - (i)
Ans. (c)
Solution.

• Glycogen is a polymer of glucose. This is a storage polysaccharide.
• Globulin is a protein associated with the immunology. Antibodies are gamma-globulins. 
• Many hormones are steroid in nature, like testosterone.
• Thrombin is a protein enzyme and is called as biocatalyst.

Q.5. Which of the following are not secondary metabolites in plants? (2021)
(a) Vinblastin, curcumin
(b) Rubber, gums
(c) Morphine, codeine
(d) Amino acids, glucose
Ans. (d)
Solution.

• Some Secondary Metabolites
• However, when one analyses plant, fungal and microbial cells, one would see thousands of compounds other than these called primary metabolites, e.g. alkaloids, flavonoids, rubber, essential oils, antibiotics, coloured pigments, scents, gums, spices.
• These are called secondary metabolites.

Q.6. Match List -I with List - II.  (2021)

Choose the correct answer from the options given below.

     (a)  (b)  (c) (d)
(a) (ii)  (i)  (iv) (iii)
(b) (iv) (iii) (i)  (ii)
(c) (iv) (i)  (ii)  (iii)
(d) (i) (iv) (iii)  (ii)
Ans. (c)
Solution. 

• Fatty acids could be saturated (without double bond) or unsaturated (with one or more C=C double bonds).
• In a polypeptide or a protein, amino acids are linked by a peptide bond which is formed when the carboxyl (-COOH) group of one amino acid reacts with the amino (-NH2) group of the next amino acid with the elimination of a water moiety (the process is called dehydration).
• In a polysaccharide the individual monosaccharides are linked by a glycosidic bond.
• As there is one such ester bond on either side, it is called phosphodiester bond.

Q.7. Identify the incorrect pair.  (2021)
(a) Lectins - Concanavalin A
(b) Drugs - Ricin
(c) Alkaloids - Codeine
(d) Toxin - Abrin
Ans. (b)
Solution. Some Secondary Metabolites

Q.8. Following are the statements with reference to 'lipids'.  (2021)
(a) Lipids having only single bonds are called unsaturated fatty acids.
(b) Lecithin is a phospholipid.
(c) Trihydroxy propane is glycerol.
(d) Palmitic acid has 20 carbon atoms including carboxyl carbon.
(e) Arachidonic acid has 16 carbon atoms.
Choose the correct answer from the options given below.
(a) (b) and (c) only
(b) (b) and (e) only
(c) (a) and (b) only
(d) (c) and (d) only
Ans. (a)
Solution.  

• For example, palmitic acid has 16 carbons including carboxyl carbon.
• Another simple lipid is glycerol which is trihydroxy propane.
• These are phospholipids.
• Lecithin is one example.

Q.9. Identify the basic amino acid from the following     (2020)
(a) Lysine
(b) Valine
(c) Tyrosine
(d) Glutamic acid 
Ans. (a)
Solution.
Lysine is the basic amino acid. Valine is neutral amino acid. Tyrosine is aromatic amino acid. Glutamic acid is acidic amino acid.

Q.10. Floridean starch has structure similar to:     (2020)
(a) Mannitol and algin
(b) Laminarin and cellulose
(c) Starch and cellulose
(d) Amylopectin and glycogen
Ans. (d)
Solution.
Floridean starch is the storage substance found in red algae (Rhodophyta). The structure of this compound is similar to amylopectin and glycogen.

Q.11. Which of the following statements is correct?     (2020)
(a) Adenine pairs with thymine through three H-bonds.
(b) Adenine does not pair with thymine.
(c) Adenine pairs with thymine through two H-bonds.
(d) Adenine pairs with thymine through one H-bond.
Ans. (c)
Solution.
Adenine pairs with thymine in DNA through two hydrogen bonds.

Q.12. Indentify the substances having glycosidic bond and peptide bond, respectively in their structure.     (2020)
(a) Cellulose, lecithin
(b) Inulin, Insulin
(c) Chitin, cholesterol
(d) Glycerol, trypsin
Ans. (b)
Solution.
Inulin is a polysaccharide have glycosidic bond, insulin is a polypeptide which is composed of two peptide chains.

Q.13. Which one of the following is the most abundant protein in the animals?     (2020)
(a) Lectin
(b) Insulin
(c) Haemoglobin
(d) Collagen
Ans. (d)
Solution.
Collagen is the most abundant protein in animal world and Ribulose bisphosphate Carboxylase-Oxygenase (RUBISCO) is the most abundant protein in the whole of the biosphere. 

Insulin is the hormone that helps in controlling the level of sugar(glucose) in the blood. Haemoglobin is the iron bound protein molecule (pigment) in the blood that helps to transport oxygen.

Q.14. Which of the following glucose transporters is insulin-dependent?    (2019)
(a) GLUT IV
(b) GLUT I
(c) GLUT II
(d) GLUT III
Ans. (a)
Solution.
GLUT stands for glucose transport protein channel. They are of different types. Glucose transporter type 4 (GLUT IV) is a protein encoded in humans by the SLC2A4 gene. It is insulin-regulated glucose transporter found primarily in adipose tissues and striated muscles.

Q.15. Concanavalin A is    (2019)
(a) A pigment
(b) An alkaloid
(c) An essential oil
(d) A lectin
Ans. (d)
Solution.
Concanavalin A, a lectin is a secondary metabolite, which has no direct function in growth and development of plants, rather are found at particular stages of development.

Q.16. Consider the following statements.
(A) Coenzyme or metal ion that is tightly bound to enzyme protein is called prosthetic group.
(B) A complete catalytic active enzyme with its bound prosthetic group is called apoenzyme.
Select the correct option.    (2019)
(a) (A) is false but (B) is true.
(b) Both (A) and (B) are true.
(c) (A) is true but (B) is false.
(d) Both (A) and (B) are false.
Ans. (d)
Solution.
Enzymes could be simple or conjugated (holoenzyme). Conjugated enzymes are formed of two parts - a protein part called apoenzyme and a non-protein part named co-factor. Co-factors are bound to the enzyme to make it catalytically active. There are three types of cofactors : prosthetic groups, co-enzymes and metal ions.
Prosthetic groups are organic compounds and are distinguished from other cofactors in which they are tightly bound to the apoenzyme. Co-enzymes are organic compounds but their association with the apoenzyme is only transient, occurring during the course of catalysis. A number of enzymes require metal ions for their activity which form coordination one or more coordination bonds with the substrate.

Q.17. "Ramachandran plot" is used to confirm the structure of    (2019)
(a) RNA
(b) proteins
(c) triacylglycerides
(d) DNA
Ans. (b)

Q.18. Prosthetic groups differ from co-enzymes in that    (2019)
(a) They require metal ions for their activity
(b) They (prosthetic groups) are tightly bound to apoenzymes
(c) Their association with apoenzymes is transient
(d) They can serve as co-factors in a number of enzyme-catalyzed reactions
Ans. (b)

Q.19. The two functional groups characteristic of sugars are    (2018)
(a) Hydroxyl and methyl
(b) Carbonyl and methyl
(c) Carbonyl and phosphate
(d) Carbonyl and hydroxyl
Ans. (d)
Solution.
Carbohydrates (commonly called sugars) are chemically defined as polyhydroxy aldehyde or ketones. All sugar molecules have one carbonyl group (-CO-) in addition to hydroxyl group (OH) on other carbon atoms.

Q.20. Which of the following statements is correct with reference to enzymes?    (2017)
(a) Holoenzyme = Apoenzyme + Coenzyme
(b) Coenzyme - Apoenzyme + Holoenzyme
(c) Holoenzyme = Coenzyme + Co-factor
(d) Apoenzyme = Holoenzyme + Coenzyme
Ans. (a)
Solution.
Holoenzyme is the complete conjugate enzyme consisting of an apoenzyme and a cofactor. Cofactor may be organic or inorganic in nature. Organic cofactors are of two types-coenzyme and prosthetic group.

Q.21. Which of the following are not polymeric?    (2017)
(a) Proteins
(b) Polysaccharides
(c) Lipids
(d) Nucleic acids
Ans. (c)
Solution.
Lipids are fatty acids esters of alcohols and related substances. Polysaccharides are polymers of monosaccharides. Proteins are polymers of amino acids and nucleic acids are polymer of nucleotides.

Q.22 A non-proteinaceous enzyme is    (2016)
(a) Lysozyme
(b) Ribozyme
(c) Ligase
(d) Deoxyribonuclease
Ans. (b)
Solution.
A ribozyme is a ribonucleic acid (RNA) enzyme that catalyses a chemical reaction in a similar way to that of a protein enzyme. These are found in ribosomes and are also called catalytic RNAs.

Q.23. Which of the following is the least likely to be involved in stabilising the three-dimensional folding of most proteins?    (2016)
(a) Hydrogen bonds
(b) Electrostatic interaction
(c) Hydrophobic interaction
(d) Ester bonds
Ans. (d)
Solution.
Tertiary structure or three dimensional structure of protein is stabilised by several types of bonds-hydrogen bonds, ionic bonds, van der Waal's interactions, covalent bonds and hydrophobic bonds.

Q.24. Which of the following describes the given graph correctly?    (2016)

(a) Endothermic reaction with energy A in presence of enzyme and B in absence of enzyme.
(b) Exothermic reaction with energy A in presence of enzyme and B in absence of enzyme.
(c) Endothermic reaction with energy A in absence of enzyme and B in presence of enzyme.
(d) Exothermic reaction with energy A in absence of enzyme and B in presence of enzyme.
Ans. (b)

Q.25. A typical fat molecule is made up of    (2016)
(a) One glycerol and one fatty acid molecule
(b) Three glycerol and three fatty acid molecules
(c) Three glycerol molecules and one fatty acid molecule
(d) One glycerol and three fatty acid molecules.
Ans. (d)
Solution.
Neutral or true fats are triglycerides which are formed by esterification of three molecules of fatty acids with one molecule of trihydric alcohol, glycerol (glycerine or trihydroxy propane).

Q.26. Which one of the following statements is wrong?    (2016)
(a) Uracil is a pyrimidine.
(b) Glycine is a sulphur containing amino acid.
(c) Sucrose is a disaccharide.
(d) Cellulose is a polysaccharide.
Ans. (b)
Solution.
Glycine is a neutral amino acid. Cysteine and methionine are sulphur containing amino acid.