NCERT NEET Biology English Medium Part-1 | Chapter 9 : Biomolecules.

NCERT NEET Biology English Medium Part-1 | Chapter 9 : Biomolecules.

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Question 1: When chemical analysis of living tissue is performed using trichloroacetic acid, which of the following is not found in the retentate?

1. a) Proteins.
2. b) Nucleic acids.
3. c) Polysaccharides.
4. d) Lipids.

Answer: d.

Question 2: Why are lipids found in the acid-insoluble fraction despite having a molecular weight less than 800 Daltons?

1. a) They are highly complex biomacromolecules.
2. b) They aggregate to form vesicles that are not water-soluble.
3. c) They form covalent bonds with proteins during extraction.
4. d) They have a highly polymeric structure.

Answer: b.

Question 3: Amino acids are substituted methanes. Which of the following functional groups does not occupy one of the four valency positions of the alpha carbon?

1. a) Carboxyl group.
2. b) Amino group.
3. c) Hydroxyl group.
4. d) Hydrogen.

Answer: c.

Question 4: Based on the nature of the R group, how many types of proteinaceous amino acids exist in nature?

10. a) 10.
11. b) 20.
12. c) 22.
13. d) Infinite.

Answer: b.

Question 5: Which of the following represents an aromatic amino acid?

1. a) Glutamic acid.
2. b) Valine.
3. c) Tyrosine.
4. d) Serine.

Answer: c.

Question 6: The zwitterionic form of an amino acid is highly dependent on which of the following factors?

1. a) Temperature of the solution.
2. b) pH of the solution.
3. c) Concentration of the amino acid.
4. d) Atmospheric pressure.

Answer: b.

Question 7: Arachidonic acid has how many carbon atoms, including the carboxyl carbon?

16. a) 16.
17. b) 18.
18. c) 20.
19. d) 22.

Answer: c.

Question 8: Palmitic acid is an example of a saturated fatty acid. How many carbon atoms does it contain excluding the carboxyl carbon?

15. a) 15.
16. b) 16.
17. c) 19.
18. d) 20.

Answer: a.

Question 9: Phospholipids are found in cell membranes. Which of the following is an example of a phospholipid?

1. a) Cholesterol.
2. b) Lecithin.
3. c) Palmitic acid.
4. d) Triglyceride.

Answer: b.

Question 10: Nitrogen bases in nucleic acids are heterocyclic compounds. Which of the following is a pyrimidine?

1. a) Adenine.
2. b) Guanine.
3. c) Uracil.
4. d) Inosine.

Answer: c.

Question 11: A nucleoside is formed by the combination of which two components?

1. a) Nitrogenous base and phosphate group.
2. b) Nitrogenous base and sugar.
3. c) Sugar and phosphate group.
4. d) Nitrogenous base, sugar, and phosphate group.

Answer: b.

Question 12: Which of the following pairs is correctly matched regarding secondary metabolites?

1. a) Alkaloids - Morphine, Codeine.
2. b) Toxins - Ricin, Concanavalin A.
3. c) Drugs - Vinblastin, Curcumin.
4. d) Lectins - Abrin, Ricin.

Answer: a.

Question 13: Concanavalin A is classified as which type of secondary metabolite?

1. a) Toxin.
2. b) Alkaloid.
3. c) Lectin.
4. d) Essential oil.

Answer: c.

Question 14: Biomacromolecules have a molecular weight usually in which of the following ranges?

1. a) 18 to 800 Daltons.
2. b) Less than 1000 Daltons.
3. c) 1000 to 5000 Daltons.
4. d) Ten thousand Daltons and above.

Answer: d.

Question 15: Which of the following biomolecules is a strict polymer?

1. a) Lipids.
2. b) Proteins.
3. c) Simple sugars.
4. d) Fatty acids.

Answer: b.

Question 16: Proteins are heteropolymers because they are composed of different monomers. What is the monomeric unit of proteins?

1. a) Monosaccharides.
2. b) Nucleotides.
3. c) Amino acids.
4. d) Fatty acids.

Answer: c.

Question 17: Essential amino acids are those which:

1. a) Can be synthesized by our body.
2. b) Must be obtained through our diet.
3. c) Are required in large quantities.
4. d) Are required for non-essential functions.

Answer: b.

Question 18: What is the most abundant protein in the animal world?

1. a) RuBisCO.
2. b) Hemoglobin.
3. c) Collagen.
4. d) Insulin.

Answer: c.

Question 19: What is the most abundant protein in the whole of the biosphere?

1. a) Ribulose bisphosphate Carboxylase-Oxygenase.
2. b) Collagen.
3. c) Trypsin.
4. d) Actin.

Answer: a.

Question 20: Polysaccharides are long chains of sugars. Which of the following is a structural polysaccharide in plants?

1. a) Starch.
2. b) Glycogen.
3. c) Cellulose.
4. d) Inulin.

Answer: c.

Question 21: Inulin is a polymer of which of the following monosaccharides?

1. a) Glucose.
2. b) Fructose.
3. c) Galactose.
4. d) Mannose.

Answer: b.

Question 22: In a polysaccharide chain, the right end is considered the:

1. a) Reducing end.
2. b) Non-reducing end.
3. c) Oxidizing end.
4. d) Non-oxidizing end.

Answer: a.

Question 23: Starch gives a blue colour with iodine because:

1. a) It has a linear, flat structure.
2. b) It forms helical secondary structures that can hold iodine molecules.
3. c) Iodine reacts chemically with glucose monomers.
4. d) Iodine causes oxidation of the starch molecule.

Answer: b.

Question 24: Why does cellulose not give a blue colour with iodine?

1. a) It does not contain complex helices to hold iodine molecules.
2. b) It is made of fructose rather than glucose.
3. c) It is highly branched and thus repels iodine.
4. d) It chemically degrades iodine.

Answer: a.

Question 25: Chitin is a complex polysaccharide found in the exoskeletons of arthropods. It is a homopolymer of which building block?

1. a) N-acetyl glucosamine.
2. b) N-acetyl muramic acid.
3. c) Glucuronic acid.
4. d) Galactosamine.

Answer: a.

Question 26: Nucleic acids are polynucleotides. What comprises a single nucleotide?

1. a) A heterocyclic compound and a monosaccharide.
2. b) A monosaccharide and a phosphoric acid.
3. c) A heterocyclic compound, a monosaccharide, and a phosphoric acid.
4. d) A nitrogenous base and a phosphate group.

Answer: c.

Question 27: The sugar found in RNA is:

1. a) 2'-deoxyribose.
2. b) Ribose.
3. c) Glucose.
4. d) Galactose.

Answer: b.

Question 28: In the primary structure of a protein, the first amino acid is also known as:

1. a) C-terminal amino acid.
2. b) N-terminal amino acid.
3. c) Alpha-amino acid.
4. d) Beta-amino acid.

Answer: b.

Question 29: Which of the following represents a secondary structure of proteins?

1. a) Linear sequence of amino acids.
2. b) Alpha-helix and beta-pleated sheet.
3. c) 3-D folding upon itself like a hollow woolen ball.
4. d) Assembly of multiple polypeptide chains.

Answer: b.

Question 30: Tertiary structure is absolutely necessary for which function of proteins?

1. a) Structural support.
2. b) Providing energy.
3. c) Many biological activities such as enzymatic actions.
4. d) Storage of genetic information.

Answer: c.

Question 31: Adult human hemoglobin consists of how many subunits?

1. a) 2 alpha type subunits.
2. b) 2 beta type subunits.
3. c) 2 alpha type and 2 beta type subunits.
4. d) 4 alpha type subunits.

Answer: c.

Question 32: In a polypeptide, amino acids are linked by which type of bond?

1. a) Glycosidic bond.
2. b) Peptide bond.
3. c) Phosphodiester bond.
4. d) Hydrogen bond.

Answer: b.

Question 33: A peptide bond is formed with the elimination of which molecule?

1. a) Carbon dioxide.
2. b) Ammonia.
3. c) Water.
4. d) Oxygen.

Answer: c.

Question 34: In a polysaccharide, individual monosaccharides are linked by:

1. a) Peptide bonds.
2. b) Phosphodiester bonds.
3. c) Glycosidic bonds.
4. d) Disulfide bonds.

Answer: c.

Question 35: In a nucleic acid, the bond between the 3'-carbon of one sugar and the 5'-carbon of the next sugar is:

1. a) Glycosidic bond.
2. b) Peptide bond.
3. c) Phosphodiester bond.
4. d) Hydrogen bond.

Answer: c.

Question 36: According to the Watson-Crick model, the DNA double helix consists of two antiparallel strands. How many hydrogen bonds are formed between Adenine and Thymine?

1. a) One.
2. b) Two.
3. c) Three.
4. d) Four.

Answer: b.

Question 37: The pitch of the B-DNA double helix is:

3. a) 3.4 Å.
4. b) 34 Å.
5. c) 34 nm.
6. d) 3.4 mm.

Answer: b.

Question 38: In B-DNA, the rise per base pair is:

1. a) 34 Å.
2. b) 3.4 Å.
3. c) 20 Å.
4. d) 3.6 Å.

Answer: b.

Question 39: The metabolic pathway that leads to the formation of cholesterol from acetic acid is an example of:

1. a) Catabolic pathway.
2. b) Anabolic pathway.
3. c) Amphibolic pathway.
4. d) Degradative pathway.

Answer: b.

Question 40: Catabolic pathways lead to the:

1. a) Consumption of energy.
2. b) Formation of complex molecules.
3. c) Release of energy.
4. d) Storage of energy.

Answer: c.

Question 41: Glycolysis, which breaks down glucose into lactic acid in skeletal muscle, involves how many metabolic steps?

5. a) 5.
6. b) 8.
7. c) 10.
8. d) 12.

Answer: c.

Question 42: The most important form of energy currency in living systems is a chemical bond energy found in:

1. a) Glucose.
2. b) ATP.
3. c) NADP.
4. d) FADH2.

Answer: b.

Question 43: The blood concentration of glucose in a normal healthy individual is roughly:

2. a) 2.0 - 3.5 mM.
3. b) 4.2 - 6.1 mM.
4. c) 10.0 - 15.0 mM.
5. d) 0.5 - 1.0 mM.

Answer: b.

Question 44: The living state is characterized as a:

1. a) Non-equilibrium steady state able to perform work.
2. b) Equilibrium state unable to perform work.
3. c) Static state with no metabolic flux.
4. d) State of maximum entropy.

Answer: a.

Question 45: Metabolism and the living state are:

1. a) Mutually exclusive.
2. b) Synonymous.
3. c) Independent of each other.
4. d) Unrelated concepts.

Answer: b.

Question 46: Almost all enzymes are:

1. a) Carbohydrates.
2. b) Lipids.
3. c) Proteins.
4. d) Nucleic acids.

Answer: c.

Question 47: Ribozymes are a class of enzymes that are biochemically made of:

1. a) RNA.
2. b) DNA.
3. c) Proteins.
4. d) Lipids.

Answer: a.

Question 48: Which structure of an enzyme is responsible for forming the active site?

1. a) Primary structure.
2. b) Secondary structure.
3. c) Tertiary structure.
4. d) Quaternary structure.

Answer: c.

Question 49: Inorganic catalysts differ from enzymes in that they:

1. a) Work efficiently at high temperatures and high pressures.
2. b) Are highly specific to a single reaction.
3. c) Are damaged at high temperatures.
4. d) Work efficiently only at low pressures.

Answer: a.

Question 50: The rate of a physical or chemical process can be defined as:

1. a) Product formed per unit volume.
2. b) Product formed per unit time.
3. c) Reactant consumed per unit mass.
4. d) Reactant consumed per unit temperature.

Answer: b.

Question 51: A general rule of thumb is that the rate of a chemical reaction doubles or decreases by half for every:

1. a) 5°C change in either direction.
2. b) 10°C change in either direction.
3. c) 20°C change in either direction.
4. d) 50°C change in either direction.

Answer: b.

Question 52: In the absence of an enzyme, the conversion of CO2 and H2O to carbonic acid yields about 200 molecules per hour. With carbonic anhydrase, the rate accelerates to:

1. a) 600,000 molecules every hour.
2. b) 600,000 molecules every minute.
3. c) 600,000 molecules every second.
4. d) 6,000 molecules every second.

Answer: c.

Question 53: The role of an enzyme is to lower the:

1. a) Total energy of the products.
2. b) Total energy of the substrate.
3. c) Activation energy.
4. d) Kinetic energy of the system.

Answer: c.

Question 54: The transition state structure of the substrate formed during an enzymatic reaction is:

1. a) Transient and stable.
2. b) Permanent and stable.
3. c) Transient and unstable.
4. d) Permanent and unstable.

Answer: c.

Question 55: If the energy level of the product is lower than that of the substrate, the reaction is:

1. a) Endothermic.
2. b) Exothermic.
3. c) Isothermic.
4. d) Non-spontaneous.

Answer: b.

Question 56: Which of the following graphical representations shows an initial increase in enzyme activity followed by a sharp decline?

1. a) Enzyme activity vs. substrate concentration.
2. b) Enzyme activity vs. temperature.
3. c) Enzyme activity vs. time.
4. d) Enzyme activity vs. enzyme concentration.

Answer: b.

Question 57: Low temperature preserves an enzyme in a temporarily inactive state, whereas high temperature destroys enzymatic activity because:

1. a) Proteins are denatured by heat.
2. b) Proteins are activated by heat.
3. c) Substrates evaporate.
4. d) The transition state becomes too stable.

Answer: a.

Question 58: The substrate concentration at which the velocity of the enzymatic reaction is half of its maximum velocity (Vmax) is called:

1. a) Turnover number.
2. b) Km (Michaelis constant).
3. c) Inhibition constant.
4. d) Equilibrium constant.

Answer: b.

Question 59: Competitive inhibition occurs when the inhibitor closely resembles the:

1. a) Product in its molecular structure.
2. b) Substrate in its molecular structure.
3. c) Enzyme's allosteric site.
4. d) Co-factor.

Answer: b.

Question 60: Malonate is a competitive inhibitor of which enzyme in the Krebs cycle?

1. a) Cytochrome oxidase.
2. b) Hexokinase.
3. c) Succinic dehydrogenase.
4. d) Pyruvate kinase.

Answer: c.

Question 61: Competitive inhibitors are often used in the medical field to control:

1. a) Viral replication.
2. b) Bacterial pathogens.
3. c) Autoimmune responses.
4. d) Genetic mutations.

Answer: b.

Question 62: Enzymes that catalyze the removal of groups from substrates by mechanisms other than hydrolysis, leaving double bonds, are classified as:

1. a) Lyases.
2. b) Hydrolases.
3. c) Ligases.
4. d) Isomerases.

Answer: a.

Question 63: Enzymes catalyzing the linking together of two compounds are known as:

1. a) Transferases.
2. b) Lyases.
3. c) Ligases.
4. d) Hydrolases.

Answer: c.

Question 64: Non-protein constituents bound to an enzyme to make it catalytically active are called:

1. a) Apoenzymes.
2. b) Co-factors.
3. c) Holoenzymes.
4. d) Proenzymes.

Answer: b.

Question 65: The protein portion of an enzyme, when a co-factor is present, is called the:

1. a) Holoenzyme.
2. b) Apoenzyme.
3. c) Prosthetic group.
4. d) Co-enzyme.

Answer: b.

Question 66: Which of the following is true about prosthetic groups?

1. a) They are loosely attached to the apoenzyme.
2. b) They are organic compounds tightly bound to the apoenzyme.
3. c) They bind to the enzyme only during catalysis.
4. d) They are inorganic metal ions.

Answer: b.

Question 67: In the enzyme peroxidase, which catalyzes the breakdown of hydrogen peroxide, the prosthetic group is:

1. a) Niacin.
2. b) Haem.
3. c) NAD.
4. d) Zinc.

Answer: b.

Question 68: Co-enzymes are organic compounds whose association with the apoenzyme is:

1. a) Permanent.
2. b) Tight and irreversible.
3. c) Transient, usually occurring during catalysis.
4. d) Non-existent.

Answer: c.

Question 69: The essential chemical components of many co-enzymes are:

1. a) Carbohydrates.
2. b) Lipids.
3. c) Vitamins.
4. d) Proteins.

Answer: c.

Question 70: NAD and NADP contain the vitamin:

1. a) Riboflavin.
2. b) Thiamine.
3. c) Niacin.
4. d) Pyridoxine.

Answer: c.

Question 71: Zinc is a crucial metal ion co-factor for the proteolytic enzyme:

1. a) Pepsin.
2. b) Carboxypeptidase.
3. c) Trypsin.
4. d) Amylase.

Answer: b.

Question 72: What happens to the catalytic activity of an enzyme when the co-factor is removed?

1. a) Activity increases drastically.
2. b) Activity remains unaffected.
3. c) Activity is completely lost.
4. d) Activity changes from catabolic to anabolic.

Answer: c.

Question 73: The primary structure of a protein dictates its:

1. a) Three-dimensional shape.
2. b) Positional information of amino acids.
3. c) Interaction with substrates.
4. d) Alpha-helix formation.

Answer: b.

Question 74: Assertion (A): Living organisms constantly require energy to maintain their highly ordered state. Reason (R): Without energy input, metabolic pathways would reach equilibrium, resulting in death.

1. a) Both A and R are true and R is the correct explanation of A.
2. b) Both A and R are true but R is not the correct explanation of A.
3. c) A is true but R is false.
4. d) Both A and R are false.

Answer: a.

Question 75: Select the incorrect statement regarding enzymes.

1. a) They lower the activation energy of a reaction.
2. b) They alter the equilibrium constant of a reaction.
3. c) They are highly specific to their substrates.
4. d) Their activity is sensitive to changes in pH.

Answer: b.

Question 76: Which of the following features is common to both glycogen and starch?

1. a) Both have beta-glycosidic bonds.
2. b) Both are structural polysaccharides.
3. c) Both are homopolymers of glucose.
4. d) Both are highly concentrated in plant cell walls.

Answer: c.

Question 77: The structure of a DNA molecule described by Watson and Crick is:

1. a) Primary structure.
2. b) Secondary structure.
3. c) Tertiary structure.
4. d) Quaternary structure.

Answer: b.

Question 78: During the formation of a phosphodiester bond, water is eliminated from:

1. a) Two hydroxyl groups.
2. b) Two amino groups.
3. c) A hydroxyl group and a phosphate group.
4. d) A carboxyl group and an amino group.

Answer: c.

Question 79: The number of carbon atoms in a ring of a ribose sugar is:

1. a) Three.
2. b) Four.
3. c) Five.
4. d) Six.

Answer: b.

Question 80: Which of the following amino acids contains a sulfur atom?

1. a) Tryptophan.
2. b) Methionine.
3. c) Tyrosine.
4. d) Proline.

Answer: b.

Question 81: An unknown biomolecule is found to have a molecular weight of 8500 Daltons and consists of carbon, hydrogen, oxygen, nitrogen, and phosphorus. It is most likely a:

1. a) Protein.
2. b) Triglyceride.
3. c) Polysaccharide.
4. d) Nucleic acid.

Answer: d.

Question 82: Which of the following forces does not contribute to the stability of the tertiary structure of proteins?

1. a) Hydrogen bonds.
2. b) Disulfide bridges.
3. c) Peptide bonds.
4. d) Hydrophobic interactions.

Answer: c.

Question 83: In competitive inhibition, how does the Vmax of the reaction change compared to an uninhibited reaction?

1. a) It increases.
2. b) It decreases.
3. c) It remains the same.
4. d) It becomes zero.

Answer: c.

Question 84: In an enzymatic reaction undergoing competitive inhibition, what happens to the Km value?

1. a) Km decreases.
2. b) Km increases.
3. c) Km remains constant.
4. d) Km fluctuates unpredictably.

Answer: b.

Question 85: The breaking of glucose to lactic acid in our skeletal muscles is called:

1. a) Citric acid cycle.
2. b) Glycolysis.
3. c) Gluconeogenesis.
4. d) Glycogenolysis.

Answer: b.

Question 86: Assertion (A): ATP is the energy currency of the cell. Reason (R): The phosphate bonds in ATP are high-energy bonds whose hydrolysis releases a large amount of energy.

1. a) Both A and R are true and R is the correct explanation of A.
2. b) Both A and R are true but R is not the correct explanation of A.
3. c) A is true but R is false.
4. d) Both A and R are false.

Answer: a.

Question 87: How many classes of enzymes are recognized by the International Union of Biochemistry?

1. a) Four classes.
2. b) Five classes.
3. c) Six classes.
4. d) Seven classes.

Answer: c.

Question 88: Enzymes are divided into subclasses, typically numbered from:

4. a) 1-4.
5. b) 4-13.
6. c) 1-10.
7. d) 1-20.

Answer: b.

Question 89: An enzyme that catalyzes the transfer of an amino group from an amino acid to a keto acid belongs to which class?

1. a) Oxidoreductases.
2. b) Transferases.
3. c) Hydrolases.
4. d) Lyases.

Answer: b.

Question 90: An exergonic reaction is characterized by:

1. a) A positive change in free energy.
2. b) The products having higher energy than the reactants.
3. c) A negative change in free energy.
4. d) Requires constant input of heat.

Answer: c.

Question 91: A biomolecule extracted in the acid-insoluble fraction but truly belonging to the micromolecule category is:

1. a) RNA.
2. b) Phospholipid.
3. c) Starch.
4. d) Myosin.

Answer: b.

Question 92: The simplest amino acid is:

1. a) Alanine.
2. b) Glycine.
3. c) Serine.
4. d) Tyrosine.

Answer: b.

Question 93: In the secondary structure of proteins, the alpha-helix is stabilized primarily by:

1. a) Ionic bonds between R groups.
2. b) Hydrogen bonds between backbone atoms.
3. c) Disulfide bonds between cysteines.
4. d) Hydrophobic interactions.

Answer: b.

Question 94: According to the dynamic state of body constituents, the turnover of a biomolecule refers to:

1. a) Its structural rigidity in the cell.
2. b) Its synthesis and degradation at a constant rate.
3. c) Its permanent storage in adipose tissue.
4. d) Its transport across the cell membrane.

Answer: b.

Question 95: Statement I: All carbon compounds that we get from living tissues can be called biomolecules. Statement II: Ash analysis helps in identifying organic biomolecules.

1. a) Both statements are correct.
2. b) Both statements are incorrect.
3. c) Statement I is correct but Statement II is incorrect.
4. d) Statement I is incorrect but Statement II is correct.

Answer: c.

Question 96: When dry weight of a tissue is fully burnt, all the carbon compounds are oxidized to gaseous form. The remaining ash primarily contains:

1. a) Complex carbohydrates.
2. b) Denatured proteins.
3. c) Inorganic elements like Calcium and Magnesium.
4. d) Insoluble lipids.

Answer: c.

Question 97: Which secondary metabolite is a known polymer?

1. a) Curcumin.
2. b) Rubber.
3. c) Lemon grass oil.
4. d) Codeine.

Answer: b.

Question 98: Statement I: Biological catalysts do not lower the activation energy, but provide an alternate pathway. Statement II: Enzymes operate best at a specific optimum pH and temperature.

1. a) Both statements are true.
2. b) Both statements are false.
3. c) Statement I is true and Statement II is false.
4. d) Statement I is false and Statement II is true.

Answer: d.

Question 99: The R group in the amino acid alanine is:

1. a) A hydrogen atom.
2. b) A methyl group.
3. c) A hydroxymethyl group.
4. d) An aromatic ring.

Answer: b.

Question 100: A biological process where the product of the reaction inhibits the key enzyme of the pathway is known as:

1. a) Competitive inhibition.
2. b) Feedback inhibition.
3. c) Non-competitive inhibition.
4. d) Irreversible inhibition.

Answer: b.

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