Q.1 Which of the following is the simplest carbohydrate?
Glucose
Fructose
Sucrose
Maltose
Explanation - Glucose is a monosaccharide, the simplest type of carbohydrate, whereas sucrose and maltose are disaccharides.
Correct answer is: Glucose
Q.2 What is the primary structural difference between saturated and unsaturated fatty acids?
Presence of a double bond
Presence of a hydroxyl group
Number of carbon atoms
Length of the carbon chain
Explanation - Saturated fatty acids have no double bonds; unsaturated fatty acids contain one or more double bonds.
Correct answer is: Presence of a double bond
Q.3 Which carbohydrate is most commonly used as a storage molecule in plants?
Starch
Glycogen
Cellulose
Chitin
Explanation - Starch is the storage polysaccharide in plants; glycogen stores energy in animals.
Correct answer is: Starch
Q.4 In the context of bacterial metabolism, which pathway is responsible for breaking down glucose anaerobically?
Glycolysis
Pentose phosphate pathway
Citric acid cycle
Oxidative phosphorylation
Explanation - Glycolysis is the anaerobic pathway that converts glucose into pyruvate, generating ATP without oxygen.
Correct answer is: Glycolysis
Q.5 Which of the following is NOT a function of lipids in cell membranes?
Provide structural integrity
Act as signaling molecules
Serve as catalysts
Regulate permeability
Explanation - Lipids act structurally and in signaling but are not catalytic enzymes.
Correct answer is: Serve as catalysts
Q.6 What type of bond links glucose units in amylose?
α-1,4-glycosidic bond
β-1,4-glycosidic bond
α-1,6-glycosidic bond
β-1,6-glycosidic bond
Explanation - Amylose is a linear polysaccharide composed of α-1,4-glycosidic linked glucose units.
Correct answer is: α-1,4-glycosidic bond
Q.7 Which fatty acid is essential for humans because it cannot be synthesized endogenously?
Oleic acid
Linoleic acid
Palmitic acid
Stearic acid
Explanation - Linoleic acid is an omega-6 fatty acid that humans must obtain from diet.
Correct answer is: Linoleic acid
Q.8 During cellular respiration, what is the primary product of glycolysis?
Lactate
Pyruvate
Acetyl-CoA
Oxygen
Explanation - Glycolysis converts glucose into two molecules of pyruvate.
Correct answer is: Pyruvate
Q.9 Which carbohydrate is a disaccharide composed of glucose and fructose?
Sucrose
Lactose
Maltose
Cellobiose
Explanation - Sucrose is a non‑reducing disaccharide made of glucose and fructose.
Correct answer is: Sucrose
Q.10 What is the main difference between beta-galactosidase and alpha-galactosidase?
Substrate specificity
Location in the cell
pH optimum
Co-factor requirement
Explanation - Beta‑galactosidase hydrolyzes β‑linkages while alpha‑galactosidase hydrolyzes α‑linkages.
Correct answer is: Substrate specificity
Q.11 Which lipid class is predominantly found in the outer leaflet of the plasma membrane?
Phosphatidylcholine
Phosphatidylethanolamine
Sphingomyelin
Glycolipids
Explanation - Glycolipids, such as gangliosides, are enriched in the outer leaflet of neuronal membranes.
Correct answer is: Glycolipids
Q.12 Which carbohydrate is most abundant in the human diet?
Glucose
Fructose
Sucrose
Maltose
Explanation - Sucrose, or table sugar, is widely consumed in processed foods.
Correct answer is: Sucrose
Q.13 Which of the following is a function of glycogen in muscle tissue?
Provide structural support
Store energy for rapid use
Facilitate ion transport
Generate ATP directly
Explanation - Muscle glycogen is a readily mobilizable energy reserve.
Correct answer is: Store energy for rapid use
Q.14 What is the most common fatty acid found in the phospholipids of mammalian cell membranes?
Palmitic acid
Oleic acid
Linoleic acid
Stearic acid
Explanation - Oleic acid is the most abundant unsaturated fatty acid in phospholipids.
Correct answer is: Oleic acid
Q.15 Which carbohydrate polymer provides rigidity to the plant cell wall?
Starch
Cellulose
Chitin
Glycogen
Explanation - Cellulose is a β‑1,4‑linked polymer that gives structural strength.
Correct answer is: Cellulose
Q.16 Which enzyme is responsible for the first step in glycolysis?
Hexokinase
Phosphofructokinase
Pyruvate kinase
Glucokinase
Explanation - Hexokinase phosphorylates glucose to glucose‑6‑phosphate.
Correct answer is: Hexokinase
Q.17 What is the role of the enzyme acyl‑CoA:cholesterol acyltransferase (ACAT)?
Synthesize cholesterol
Convert cholesterol to bile acids
Store cholesterol as esters
Break down triglycerides
Explanation - ACAT esterifies free cholesterol for storage in lipid droplets.
Correct answer is: Store cholesterol as esters
Q.18 Which of the following sugars is a hexose?
Glucose
Glycerol
Maltose
Fructose
Explanation - Glucose is a six‑carbon hexose; fructose is also a hexose but often paired in sucrose.
Correct answer is: Glucose
Q.19 Which lipid is used by the body to store long‑term energy?
Phospholipids
Triglycerides
Steroids
Glycolipids
Explanation - Triglycerides are stored in adipose tissue and mobilized for energy.
Correct answer is: Triglycerides
Q.20 Which carbohydrate is a pentose sugar?
Fructose
Ribose
Glucose
Sucrose
Explanation - Ribose is a five‑carbon pentose sugar found in RNA.
Correct answer is: Ribose
Q.21 What type of linkage is formed in the backbone of cellulose?
α‑1,4‑glycosidic
β‑1,4‑glycosidic
α‑1,6‑glycosidic
β‑1,6‑glycosidic
Explanation - Cellulose is composed of β‑1,4‑linked glucose units.
Correct answer is: β‑1,4‑glycosidic
Q.22 Which enzyme breaks down triglycerides into glycerol and fatty acids?
Lipase
Amylase
Protease
Glucokinase
Explanation - Lipases hydrolyze ester bonds in triglycerides.
Correct answer is: Lipase
Q.23 Which component of a cell membrane is primarily responsible for passive diffusion of small molecules?
Phospholipid bilayer
Cholesterol
Integral proteins
Extracellular matrix
Explanation - The bilayer allows passive diffusion of lipophilic substances.
Correct answer is: Phospholipid bilayer
Q.24 Which carbohydrate is a storage polysaccharide in fungi?
Glycogen
Chitin
Cellulose
Starch
Explanation - Fungi store glycogen similarly to animals.
Correct answer is: Glycogen
Q.25 What is the main difference between omega‑3 and omega‑6 fatty acids?
Position of the first double bond
Number of carbons
Presence of a hydroxyl group
Chain length
Explanation - Omega‑3s have a double bond at the third carbon from the methyl end; omega‑6 at the sixth.
Correct answer is: Position of the first double bond
Q.26 Which of the following is NOT a function of carbohydrates?
Energy source
Structural component
Enzyme activity
Signal transduction
Explanation - Carbohydrates do not act as enzymes; they provide energy, structure, and signaling roles.
Correct answer is: Enzyme activity
Q.27 What is the main product of fatty acid β‑oxidation?
Acetyl‑CoA
Pyruvate
Lactate
Glucose
Explanation - Each cycle of β‑oxidation generates an acetyl‑CoA unit.
Correct answer is: Acetyl‑CoA
Q.28 Which sugar is the end product of glycolysis?
Glucose
Glucose‑6‑phosphate
Pyruvate
Glyceraldehyde‑3‑phosphate
Explanation - Glycolysis splits glucose into two pyruvate molecules.
Correct answer is: Pyruvate
Q.29 What is the structural difference between triglycerides and phospholipids?
Triglycerides contain a phosphate group
Triglycerides have three fatty acids; phospholipids have two
Triglycerides are polar; phospholipids are non‑polar
Triglycerides are used in membranes; phospholipids store energy
Explanation - Triglycerides have three esterified fatty acids; phospholipids have two fatty acids and one phosphate head.
Correct answer is: Triglycerides have three fatty acids; phospholipids have two
Q.30 Which carbohydrate polymer forms the primary structural component of fungal cell walls?
Glucan
Chitin
Lignin
Cellulose
Explanation - Chitin is a β‑1,4‑linked polymer of N‑acetylglucosamine found in fungal walls.
Correct answer is: Chitin
Q.31 Which of the following is an example of a non‑reducing sugar?
Glucose
Fructose
Sucrose
Maltose
Explanation - Sucrose lacks free aldehyde or ketone groups; thus it is non‑reducing.
Correct answer is: Sucrose
Q.32 Which enzyme is involved in the synthesis of phosphatidylcholine via the CDP‑choline pathway?
Choline kinase
Cytidylyl‑phosphatidyl‑choline synthase
Choline phosphotransferase
Choline‑phospho‑glycine transferase
Explanation - This enzyme catalyzes the formation of CDP‑choline, a key intermediate.
Correct answer is: Cytidylyl‑phosphatidyl‑choline synthase
Q.33 In bacterial cell membranes, which lipid component provides a barrier to water?
Phosphatidylglycerol
Cardiolipin
Phosphatidylethanolamine
Phosphatidylinositol
Explanation - Phosphatidylglycerol is a major anionic phospholipid that maintains membrane integrity.
Correct answer is: Phosphatidylglycerol
Q.34 Which carbohydrate is the most common component of the glycocalyx?
Glucose
Galactose
Mannose
Fucose
Explanation - Mannose residues are frequently found in glycoprotein glycans.
Correct answer is: Mannose
Q.35 Which of the following is a product of the oxidative pentose phosphate pathway?
NADPH
ATP
Acetyl‑CoA
GTP
Explanation - The pathway generates NADPH for reductive biosynthesis.
Correct answer is: NADPH
Q.36 Which type of fatty acid chain is most flexible?
Saturated fatty acid
Monounsaturated fatty acid
Polyunsaturated fatty acid
Cholesterol
Explanation - Multiple double bonds create kinks, increasing fluidity.
Correct answer is: Polyunsaturated fatty acid
Q.37 What is the role of glycogen phosphorylase?
Glycogen synthesis
Glycogen breakdown
Glucose transport
Lipid synthesis
Explanation - Glycogen phosphorylase cleaves glucose units from glycogen.
Correct answer is: Glycogen breakdown
Q.38 Which carbohydrate is a building block of DNA?
Glucose
Ribose
Deoxyribose
Maltose
Explanation - DNA contains deoxyribose sugar in its backbone.
Correct answer is: Deoxyribose
Q.39 Which enzyme catalyzes the transfer of a phosphate group from ATP to a fatty acid?
Acyl‑CoA synthase
Lipase
Phosphatase
Kinase
Explanation - Acyl‑CoA synthase activates fatty acids by attaching CoA.
Correct answer is: Acyl‑CoA synthase
Q.40 Which lipid is directly involved in the synthesis of steroid hormones?
Cholesterol
Phosphatidylinositol
Phosphatidylserine
Lecithin
Explanation - Cholesterol serves as the precursor for steroid hormones.
Correct answer is: Cholesterol
Q.41 Which carbohydrate is a component of the extracellular matrix of bone?
Hyaluronic acid
Collagen
Elastin
Keratin
Explanation - Hyaluronic acid is a glycosaminoglycan found in bone ECM.
Correct answer is: Hyaluronic acid
Q.42 Which of the following is a characteristic of saturated fats?
Higher melting point
Lower caloric value
Increased flexibility
Presence of double bonds
Explanation - Saturated fats are solid at room temperature due to straight chains.
Correct answer is: Higher melting point
Q.43 What is the main carbohydrate used for rapid energy during intense exercise?
Starch
Glycogen
Cellulose
Chitin
Explanation - Glycogen stores in muscle provide quick glucose supply.
Correct answer is: Glycogen
Q.44 Which enzyme is inhibited by high concentrations of ATP?
Hexokinase
Phosphofructokinase
Pyruvate kinase
Glucose‑6‑phosphatase
Explanation - Phosphofructokinase is allosterically inhibited by ATP to regulate glycolysis.
Correct answer is: Phosphofructokinase
Q.45 Which lipid class contains a sphingosine backbone?
Phospholipids
Glycolipids
Sphingolipids
Triacylglycerols
Explanation - Sphingolipids are built on a sphingosine backbone.
Correct answer is: Sphingolipids
Q.46 Which carbohydrate is the primary energy source for the brain?
Glucose
Fructose
Maltose
Sucrose
Explanation - The brain relies almost exclusively on glucose.
Correct answer is: Glucose
Q.47 In which organelles is fatty acid synthesis primarily performed in eukaryotes?
Mitochondria
Endoplasmic reticulum
Chloroplasts
Nucleus
Explanation - Fatty acid synthase complexes reside in the cytosol and on the ER membrane.
Correct answer is: Endoplasmic reticulum
Q.48 What is the major product of glycolysis that enters the citric acid cycle under aerobic conditions?
Acetyl‑CoA
Pyruvate
Lactate
Oxygen
Explanation - Pyruvate is converted to Acetyl‑CoA by pyruvate dehydrogenase.
Correct answer is: Acetyl‑CoA
Q.49 Which of the following is NOT a type of carbohydrate polymer?
Polysaccharides
Dextrins
Monosaccharides
Trisaccharides
Explanation - Trisaccharides are not a distinct class; they are simply a type of oligosaccharide.
Correct answer is: Trisaccharides
Q.50 What is the primary function of cholesterol in animal cell membranes?
Serve as an enzyme
Reduce membrane fluidity
Act as a storage molecule
Provide structural support
Explanation - Cholesterol modulates fluidity and stability.
Correct answer is: Reduce membrane fluidity
Q.51 Which carbohydrate polymer is found in the insect cuticle?
Chitin
Cellulose
Starch
Glycogen
Explanation - Chitin provides structural support in insects.
Correct answer is: Chitin
Q.52 Which of the following sugars is a ketose?
Glucose
Fructose
Maltose
Sucrose
Explanation - Fructose contains a ketone functional group.
Correct answer is: Fructose
Q.53 Which enzyme is involved in the conversion of acetyl‑CoA to malonyl‑CoA?
Acetyl‑CoA carboxylase
HMG‑CoA reductase
β‑hydroxy β‑methylglutaryl‑CoA lyase
Phosphatidylserine synthase
Explanation - Acetyl‑CoA carboxylase catalyzes the first committed step in fatty acid synthesis.
Correct answer is: Acetyl‑CoA carboxylase
Q.54 What is the main role of the enzyme phosphofructokinase‑1 in glycolysis?
Phosphorylate glucose
Convert fructose‑6‑phosphate to fructose‑1,6‑bisphosphate
Generate ATP from ADP
Oxidize pyruvate
Explanation - PFK‑1 is a key regulatory step in glycolysis.
Correct answer is: Convert fructose‑6‑phosphate to fructose‑1,6‑bisphosphate
Q.55 Which lipid component is characteristic of bacterial outer membranes?
Lipopolysaccharide
Phosphatidylglycerol
Cardiolipin
Phosphatidylinositol
Explanation - Lipopolysaccharides provide a protective barrier in Gram‑negative bacteria.
Correct answer is: Lipopolysaccharide
Q.56 Which of the following carbohydrates is most abundant in the human diet?
Glucose
Fructose
Sucrose
Maltose
Explanation - Sucrose is widely consumed in processed foods and beverages.
Correct answer is: Sucrose
Q.57 What is the primary site of glycolysis in eukaryotic cells?
Nucleus
Mitochondria
Cytosol
Endoplasmic reticulum
Explanation - Glycolysis occurs in the cytoplasmic compartment.
Correct answer is: Cytosol
Q.58 Which of the following is a type of dietary fiber?
Resistant starch
Glycerol
Cholesterol
Phospholipid
Explanation - Resistant starch is not digested in the small intestine and acts as fiber.
Correct answer is: Resistant starch
Q.59 Which of the following lipids is synthesized in the liver and used for bile formation?
Cholesterol
Triglycerides
Phosphatidylcholine
Sphingomyelin
Explanation - Phosphatidylcholine is the main phospholipid in bile.
Correct answer is: Phosphatidylcholine
Q.60 Which enzyme catalyzes the first step in the synthesis of chitin?
Chitin synthase
Chitinase
Glucan synthase
Cellulose synthase
Explanation - Chitin synthase polymerizes N‑acetylglucosamine to form chitin.
Correct answer is: Chitin synthase
Q.61 What type of linkage is found in lactose?
α‑1,4
β‑1,4
α‑1,3
β‑1,3
Explanation - Lactose is a β‑1,4‑linked disaccharide of glucose and galactose.
Correct answer is: β‑1,4
Q.62 Which carbohydrate is a component of bacterial cell walls and is a target of lysozyme?
Peptidoglycan
Chitin
Cellulose
Glucan
Explanation - Lysozyme hydrolyzes the β‑1,4 linkages in peptidoglycan.
Correct answer is: Peptidoglycan
Q.63 Which enzyme is responsible for converting fatty acyl‑CoA to fatty acid?
Acyl‑CoA thioesterase
Lipase
Acyl‑transferase
Cholesterol synthase
Explanation - Acyl‑CoA thioesterase hydrolyzes acyl‑CoA to release free fatty acids.
Correct answer is: Acyl‑CoA thioesterase
Q.64 What is the main carbohydrate component of the hemagglutinin of influenza virus?
Mannose
Glucose
Galactose
Sialic acid
Explanation - Influenza hemagglutinin binds sialic acid residues on host cells.
Correct answer is: Sialic acid
Q.65 Which of the following is a non‑sugar component of glycolipids?
Ceramide
Fatty acid
Cholesterol
Glycerol
Explanation - Ceramide is the sphingoid base component of sphingolipids.
Correct answer is: Ceramide
Q.66 Which of the following is a characteristic of disaccharides?
They are polymeric
They consist of two monosaccharides
They are always reducing sugars
They contain a glycosidic bond
Explanation - Disaccharides are formed from two monosaccharides linked by a glycosidic bond.
Correct answer is: They consist of two monosaccharides
Q.67 Which carbohydrate is the main component of the plant vacuole storage?
Starch
Cellulose
Glycogen
Chitin
Explanation - Starch accumulates in plant vacuoles for energy storage.
Correct answer is: Starch
Q.68 Which enzyme is involved in the breakdown of cellulose?
Cellulase
Amylase
Lipase
Protease
Explanation - Cellulase hydrolyzes β‑1,4 bonds in cellulose.
Correct answer is: Cellulase
Q.69 Which of the following is a major source of omega‑3 fatty acids?
Fish oil
Sunflower oil
Olive oil
Soybean oil
Explanation - Fish oil is rich in EPA and DHA omega‑3 fatty acids.
Correct answer is: Fish oil
Q.70 What type of glycosidic bond is found in maltose?
α‑1,4
β‑1,4
α‑1,6
β‑1,6
Explanation - Maltose is an α‑1,4‑linked disaccharide of glucose.
Correct answer is: α‑1,4
Q.71 Which of the following enzymes is responsible for the synthesis of ceramide in sphingolipid metabolism?
Ceramide synthase
Sphingomyelinase
Cholesterol esterase
Glucose‑6‑phosphatase
Explanation - Ceramide synthase catalyzes the N‑acylation of sphingosine.
Correct answer is: Ceramide synthase
Q.72 Which carbohydrate is used by bacteria to create biofilm exopolysaccharides?
Polysaccharide
Monosaccharide
Disaccharide
Oligosaccharide
Explanation - Bacteria produce polysaccharide matrices for biofilms.
Correct answer is: Polysaccharide
Q.73 Which enzyme is involved in the phosphorylation of pyruvate to acetyl‑CoA?
Pyruvate dehydrogenase
Pyruvate carboxylase
Phosphofructokinase
Aldolase
Explanation - Pyruvate dehydrogenase converts pyruvate to acetyl‑CoA.
Correct answer is: Pyruvate dehydrogenase
Q.74 Which lipid is essential for the formation of the myelin sheath in neurons?
Phosphatidylcholine
Cholesterol
Phosphatidylserine
Phosphatidylinositol
Explanation - Cholesterol provides compactness to myelin membranes.
Correct answer is: Cholesterol
Q.75 Which carbohydrate is a major component of insect exoskeletons?
Chitin
Cellulose
Glycogen
Starch
Explanation - Chitin forms the structural framework of the exoskeleton.
Correct answer is: Chitin
Q.76 What is the main function of the enzyme acetyl‑CoA carboxylase?
Convert acetyl‑CoA to malonyl‑CoA
Oxidize fatty acids
Synthesize cholesterol
Break down triglycerides
Explanation - Acetyl‑CoA carboxylase catalyzes the first step in fatty acid synthesis.
Correct answer is: Convert acetyl‑CoA to malonyl‑CoA
Q.77 Which carbohydrate is a component of the bacterial endotoxin?
Peptidoglycan
Lipopolysaccharide
Lipid A
Phosphatidylglycerol
Explanation - LPS contains lipid A and polysaccharide chains.
Correct answer is: Lipopolysaccharide
Q.78 Which of the following is a major source of dietary fiber in cereals?
Cellulose
Starch
Glucose
Lactose
Explanation - Cellulose is indigestible fiber in plant cell walls.
Correct answer is: Cellulose
Q.79 Which of the following is an example of a disaccharide that is non‑reducing?
Lactose
Sucrose
Maltose
Cellobiose
Explanation - Sucrose lacks a free aldehyde or ketone group.
Correct answer is: Sucrose
Q.80 Which enzyme catalyzes the hydrolysis of triglycerides into glycerol and free fatty acids?
Lipase
Amylase
Protease
Phospholipase
Explanation - Lipase hydrolyzes ester bonds in triglycerides.
Correct answer is: Lipase
Q.81 Which fatty acid is the main component of olive oil?
Oleic acid
Linoleic acid
Palmitic acid
Stearic acid
Explanation - Oleic acid is the predominant monounsaturated fatty acid.
Correct answer is: Oleic acid
Q.82 Which of the following is a key enzyme in the synthesis of cell wall peptidoglycan?
MurA
MurB
MurC
MurD
Explanation - MurA catalyzes the first step of peptidoglycan precursor synthesis.
Correct answer is: MurA
Q.83 Which carbohydrate is a major component of the human intestinal mucus?
Mucin
Collagen
Keratin
Elastin
Explanation - Mucins are glycoproteins rich in carbohydrate chains.
Correct answer is: Mucin
Q.84 What type of carbohydrate is sucrose?
Reducing disaccharide
Non‑reducing disaccharide
Monosaccharide
Oligosaccharide
Explanation - Sucrose has no free aldehyde or ketone groups.
Correct answer is: Non‑reducing disaccharide
Q.85 Which enzyme is responsible for the synthesis of sphingomyelin?
Sphingomyelin synthase
Sphingomyelinase
Ceramidase
Acyltransferase
Explanation - Sphingomyelin synthase transfers phosphocholine to ceramide.
Correct answer is: Sphingomyelin synthase
Q.86 Which of the following carbohydrates is a storage polysaccharide in bacteria?
Glycogen
Cellulose
Chitin
Starch
Explanation - Bacteria store energy as glycogen.
Correct answer is: Glycogen
Q.87 Which lipid class is involved in the formation of the inner membrane of mitochondria?
Cardiolipin
Phosphatidylcholine
Phosphatidylethanolamine
Cholesterol
Explanation - Cardiolipin is enriched in mitochondrial membranes.
Correct answer is: Cardiolipin
Q.88 Which carbohydrate is a component of the exopolysaccharide matrix of biofilms?
Pseudaminic acid
Lactose
Mannan
Chitin
Explanation - Mannans are common exopolysaccharides in biofilms.
Correct answer is: Mannan
Q.89 Which of the following is a key step in the breakdown of glycogen in muscle cells?
Glycogen synthase activation
Glycogen phosphorylase activation
Phosphofructokinase activation
Pyruvate kinase activation
Explanation - Glycogen phosphorylase breaks glycogen into glucose‑1‑phosphate.
Correct answer is: Glycogen phosphorylase activation
Q.90 Which enzyme is responsible for the final step in glycolysis that produces ATP?
Pyruvate kinase
Hexokinase
Phosphofructokinase
Aldolase
Explanation - Pyruvate kinase catalyzes the transfer of a phosphate to ADP, generating ATP.
Correct answer is: Pyruvate kinase
Q.91 What is the main component of the human blood plasma lipid composition?
Triglycerides
Phospholipids
Cholesterol
Ceramides
Explanation - Cholesterol constitutes the largest proportion of plasma lipids.
Correct answer is: Cholesterol
Q.92 Which carbohydrate polymer is responsible for the rigidity of plant cell walls?
Starch
Cellulose
Glycogen
Lignin
Explanation - Cellulose provides tensile strength in plant cell walls.
Correct answer is: Cellulose
Q.93 Which of the following enzymes breaks down β‑glycerophosphate?
Phosphoglycerate mutase
Phosphatase
Kinase
Isomerase
Explanation - Phosphatases hydrolyze phosphate groups from substrates.
Correct answer is: Phosphatase
Q.94 Which lipid is primarily responsible for the barrier function in the stratum corneum?
Ceramides
Phosphatidylcholine
Cholesterol
Sphingomyelin
Explanation - Ceramides create a waterproof barrier in the skin.
Correct answer is: Ceramides
Q.95 What is the main carbohydrate source of the human diet that is used for long‑term storage in animals?
Glucose
Glycogen
Starch
Lactose
Explanation - Animals store glycogen in liver and muscle for long‑term energy.
Correct answer is: Glycogen
Q.96 Which enzyme is involved in the synthesis of the myelin sheath in Schwann cells?
Ceramide synthase
Acyl‑CoA oxidase
Cholesterol synthase
Glycogen synthase
Explanation - Ceramides are key components in myelin production.
Correct answer is: Ceramide synthase
Q.97 Which carbohydrate is a component of the bacterial flagellin structure?
N‑acetylglucosamine
Mannose
Glucose
Galactose
Explanation - Flagellin often contains N‑acetylglucosamine residues.
Correct answer is: N‑acetylglucosamine
Q.98 Which enzyme catalyzes the addition of a phosphate group to glucose in the first step of glycolysis?
Hexokinase
Phosphofructokinase
Pyruvate kinase
Aldolase
Explanation - Hexokinase phosphorylates glucose to glucose‑6‑phosphate.
Correct answer is: Hexokinase
Q.99 Which of the following is NOT a function of carbohydrates in living organisms?
Energy source
Structural component
Enzymatic catalysis
Signal transduction
Explanation - Carbohydrates do not act as enzymes; they serve structural and energetic roles.
Correct answer is: Enzymatic catalysis
Q.100 Which fatty acid is a major component of soybean oil?
Linoleic acid
Oleic acid
Palmitic acid
Stearic acid
Explanation - Soybean oil contains high levels of linoleic (omega‑6) fatty acids.
Correct answer is: Linoleic acid
Q.101 Which of the following enzymes is responsible for the polymerization of N‑acetylglucosamine into chitin?
Chitin synthase
Chitinase
Glucan synthase
Cellulose synthase
Explanation - Chitin synthase polymerizes N‑acetylglucosamine into a chitin polymer.
Correct answer is: Chitin synthase
Q.102 Which carbohydrate is the main structural component of insect exoskeletons?
Chitin
Cellulose
Glycogen
Starch
Explanation - Chitin forms the rigid exoskeleton of insects.
Correct answer is: Chitin
Q.103 What is the main product of the breakdown of glycogen in the liver during fasting?
Glucose‑6‑phosphate
Glucose
Pyruvate
Lactate
Explanation - Liver glycogen is converted to free glucose for release into the bloodstream.
Correct answer is: Glucose
Q.104 Which of the following is a major source of dietary fiber in whole grains?
Cellulose
Starch
Glycogen
Maltose
Explanation - Cellulose is the indigestible fiber in plant cell walls.
Correct answer is: Cellulose
Q.105 Which of the following fatty acids has the greatest degree of unsaturation?
Oleic acid
Linoleic acid
Palmitic acid
Stearic acid
Explanation - Linoleic acid has two double bonds, more unsaturated than oleic.
Correct answer is: Linoleic acid
Q.106 Which enzyme is responsible for converting diacylglycerol into triacylglycerol?
Lipase
Acyltransferase
Phospholipase
Glycerol kinase
Explanation - Acyltransferase adds a fatty acyl group to diacylglycerol forming triglyceride.
Correct answer is: Acyltransferase
Q.107 Which carbohydrate is the main component of plant seeds used as a storage form of energy?
Starch
Cellulose
Glycogen
Chitin
Explanation - Starch is stored in seeds as the primary energy reserve.
Correct answer is: Starch
Q.108 Which of the following enzymes is responsible for the first step in the synthesis of sphingolipids?
Serine palmitoyltransferase
Sphingomyelin synthase
Ceramidase
Acyl‑CoA oxidase
Explanation - This enzyme catalyzes the condensation of serine and palmitoyl‑CoA.
Correct answer is: Serine palmitoyltransferase
Q.109 Which carbohydrate is a major component of the extracellular matrix of the cartilage?
Hyaluronic acid
Collagen
Elastin
Fibronectin
Explanation - Hyaluronic acid is a glycosaminoglycan found in cartilage.
Correct answer is: Hyaluronic acid
Q.110 Which of the following is a characteristic of beta‑glucan?
Linear β‑1,3 linkage
Branching β‑1,4 linkage
α‑glycosidic bond
Non‑reducing end
Explanation - β‑Glucans are usually β‑1,3‑linked with occasional β‑1,6 branches.
Correct answer is: Linear β‑1,3 linkage
Q.111 Which enzyme is responsible for the breakdown of maltose into glucose?
Maltase
Sucrase
Lactase
α‑Glucosidase
Explanation - Maltase hydrolyzes maltose into two glucose molecules.
Correct answer is: Maltase
Q.112 Which of the following lipids is involved in the formation of the inner mitochondrial membrane?
Cardiolipin
Cholesterol
Phosphatidylcholine
Phosphatidylserine
Explanation - Cardiolipin is a distinctive phospholipid of mitochondria.
Correct answer is: Cardiolipin
Q.113 What is the primary function of the enzyme phosphofructokinase‑1?
Regulate glycolysis
Convert pyruvate to lactate
Generate ATP
Break down glycogen
Explanation - PFK‑1 is the rate‑limiting step in glycolysis.
Correct answer is: Regulate glycolysis
Q.114 Which of the following is a characteristic of the glycosaminoglycan hyaluronic acid?
Contains repeating disaccharide units
Is sulfated
Is non‑sulfated
Contains N‑acetylglucosamine
Explanation - Hyaluronic acid lacks sulfate groups, unlike other GAGs.
Correct answer is: Is non‑sulfated
Q.115 Which enzyme is responsible for the final step of fatty acid synthesis?
Thioesterase
Acyl‑CoA synthase
Fatty acid synthase
Acyltransferase
Explanation - Fatty acid synthase catalyzes the chain elongation process.
Correct answer is: Fatty acid synthase
Q.116 Which carbohydrate is a component of the human breast milk?
Lactose
Fructose
Glucose
Sucrose
Explanation - Lactose is the main sugar in human milk.
Correct answer is: Lactose
Q.117 Which of the following is a major source of dietary omega‑6 fatty acids?
Sunflower oil
Fish oil
Olive oil
Almond oil
Explanation - Sunflower oil is rich in linoleic acid (omega‑6).
Correct answer is: Sunflower oil
Q.118 Which enzyme converts acetyl‑CoA into malonyl‑CoA during fatty acid synthesis?
Acetyl‑CoA carboxylase
Acetyl‑CoA synthase
Acetyl‑CoA oxidase
Acetyl‑CoA transferase
Explanation - This carboxylation step is the first committed step in fatty acid biosynthesis.
Correct answer is: Acetyl‑CoA carboxylase
Q.119 Which carbohydrate is a non‑reducing disaccharide commonly found in fruit juices?
Sucrose
Maltose
Lactose
Cellobiose
Explanation - Sucrose is a non‑reducing sugar found in many fruits.
Correct answer is: Sucrose
Q.120 Which lipid is essential for the formation of the myelin sheath around nerve fibers?
Cholesterol
Phosphatidylcholine
Phosphatidylserine
Phosphatidylinositol
Explanation - Cholesterol is critical for myelin membrane stability.
Correct answer is: Cholesterol
Q.121 Which of the following enzymes is involved in the degradation of cell wall peptidoglycan?
Peptidoglycan‑binding protein
MurNAc‑amidase
Transglycosylase
Glycosyltransferase
Explanation - MurNAc‑amidase hydrolyzes the amide bond in peptidoglycan.
Correct answer is: MurNAc‑amidase
Q.122 Which carbohydrate is the main component of plant seeds used for energy storage?
Starch
Cellulose
Glycogen
Maltose
Explanation - Starch is the predominant storage carbohydrate in seeds.
Correct answer is: Starch
Q.123 What is the primary function of the enzyme hexokinase in glycolysis?
Phosphorylate glucose
Oxidize pyruvate
Produce ATP
Synthesize glycogen
Explanation - Hexokinase initiates glycolysis by converting glucose to glucose‑6‑phosphate.
Correct answer is: Phosphorylate glucose
Q.124 Which of the following is NOT a major component of the bacterial cell membrane?
Phosphatidylglycerol
Cardiolipin
Cholesterol
Phosphatidylethanolamine
Explanation - Bacterial membranes contain phospholipids and cardiolipin but lack cholesterol.
Correct answer is: Cholesterol
Q.125 Which carbohydrate is a key structural component of the extracellular matrix in fungi?
Chitin
Cellulose
Glycogen
Starch
Explanation - Chitin forms the cell wall of fungi.
Correct answer is: Chitin
Q.126 Which lipid class is most abundant in the human brain?
Cholesterol
Phosphatidylserine
Sphingomyelin
Cardiolipin
Explanation - Sphingomyelin is a major component of the brain's myelin sheath.
Correct answer is: Sphingomyelin
Q.127 Which of the following is a major source of dietary fiber in oats?
Beta‑glucan
Starch
Cellulose
Lactose
Explanation - Beta‑glucan is a soluble fiber found in oats.
Correct answer is: Beta‑glucan
Q.128 Which of the following fatty acids is a major component of fish oils?
EPA
EPA
Oleic acid
Palmitic acid
Explanation - Eicosapentaenoic acid (EPA) is an omega‑3 fatty acid abundant in fish oil.
Correct answer is: EPA
Q.129 Which enzyme is responsible for the first step in the synthesis of phosphatidylcholine?
Cytidylyl‑phosphatidyl‑choline synthase
Choline kinase
Choline phosphotransferase
Choline‑phospho‑glycine transferase
Explanation - This enzyme synthesizes CDP‑choline from phosphocholine.
Correct answer is: Cytidylyl‑phosphatidyl‑choline synthase
Q.130 Which of the following is a major component of the plant cell wall?
Cellulose
Starch
Glycogen
Chitin
Explanation - Cellulose provides structural support in plants.
Correct answer is: Cellulose
Q.131 Which of the following is NOT a function of triglycerides?
Long‑term energy storage
Lipid transport
Structural support
Heat insulation
Explanation - Triglycerides store energy; lipids like phospholipids transport across membranes.
Correct answer is: Lipid transport
Q.132 Which enzyme is responsible for converting diacylglycerol to triacylglycerol?
Acyltransferase
Lipase
Phospholipase
Glycerol kinase
Explanation - Acyltransferase adds a fatty acyl group to diacylglycerol to produce triacylglycerol.
Correct answer is: Acyltransferase
Q.133 Which carbohydrate is a component of the human stomach mucus?
Mucin
Collagen
Elastin
Fibronectin
Explanation - Mucins are glycoproteins rich in carbohydrate chains.
Correct answer is: Mucin
Q.134 Which lipid is the major component of the mitochondrial inner membrane that participates in electron transport?
Cardiolipin
Cholesterol
Phosphatidylcholine
Phosphatidylserine
Explanation - Cardiolipin anchors electron transport chain complexes.
Correct answer is: Cardiolipin
Q.135 Which of the following is a characteristic of the sugar sucrose?
Reducing sugar
Non‑reducing sugar
Monosaccharide
Oligosaccharide
Explanation - Sucrose has no free aldehyde or ketone functional group.
Correct answer is: Non‑reducing sugar
Q.136 Which of the following is a major source of dietary fiber in wheat bran?
Cellulose
Starch
Glycogen
Maltose
Explanation - Cellulose provides insoluble fiber in wheat bran.
Correct answer is: Cellulose
Q.137 Which enzyme catalyzes the addition of a phosphate to the 1‑st carbon of glycerol?
Glycerol kinase
Phosphatidylserine synthase
Phospholipase
Lipase
Explanation - Glycerol kinase phosphorylates glycerol to glycerol‑3‑phosphate.
Correct answer is: Glycerol kinase
Q.138 Which carbohydrate is the main structural component of the exoskeleton of arthropods?
Chitin
Cellulose
Glycogen
Starch
Explanation - Chitin forms the rigid exoskeleton of arthropods.
Correct answer is: Chitin
Q.139 Which enzyme is responsible for the synthesis of fatty acids in the mitochondria?
Acyl‑CoA synthase
Acyl‑CoA oxidase
Acyl‑transferase
Fatty acid synthase
Explanation - Acyl‑CoA oxidase catalyzes the first step of β‑oxidation in mitochondria.
Correct answer is: Acyl‑CoA oxidase
Q.140 Which of the following is a major component of the human brain’s white matter?
Sphingomyelin
Phosphatidylcholine
Phosphatidylserine
Cardiolipin
Explanation - Sphingomyelin is abundant in myelin sheaths.
Correct answer is: Sphingomyelin
Q.141 Which enzyme breaks down the disaccharide lactose into glucose and galactose?
Lactase
Sucrase
Maltase
Mannase
Explanation - Lactase hydrolyzes lactose into its monosaccharide constituents.
Correct answer is: Lactase
Q.142 Which of the following is a characteristic of the lipid sphingomyelin?
Contains a sphingosine backbone
Contains a glycerol backbone
Has a phosphatidylserine headgroup
Is found in mitochondria only
Explanation - Sphingomyelin is built on a sphingosine backbone.
Correct answer is: Contains a sphingosine backbone
Q.143 Which of the following enzymes is responsible for the first step in the synthesis of the cell wall peptidoglycan?
MurA
MurB
MurC
MurD
Explanation - MurA catalyzes the formation of the UDP‑N‑acetylmuramic acid precursor.
Correct answer is: MurA
Q.144 Which carbohydrate polymer is primarily used by fungi for structural support?
Chitin
Starch
Cellulose
Glycogen
Explanation - Chitin forms the cell wall of fungi.
Correct answer is: Chitin
Q.145 Which enzyme is responsible for the conversion of acetyl‑CoA to malonyl‑CoA during fatty acid synthesis?
Acetyl‑CoA carboxylase
Acetyl‑CoA synthase
Acetyl‑CoA oxidase
Acetyl‑CoA transferase
Explanation - Acetyl‑CoA carboxylase catalyzes the first committed step of fatty acid synthesis.
Correct answer is: Acetyl‑CoA carboxylase
Q.146 Which of the following is NOT a major function of lipids in eukaryotic cells?
Store energy
Facilitate cell signaling
Act as enzymes
Form membrane structures
Explanation - Lipids are structural and storage molecules; enzymes are proteins.
Correct answer is: Act as enzymes
Q.147 Which of the following is a major source of dietary fiber in legumes?
Cellulose
Pectin
Hemicellulose
Starch
Explanation - Pectin is a soluble fiber found in legumes.
Correct answer is: Pectin
Q.148 Which of the following fatty acids is most commonly found in the cell membrane of plants?
Linoleic acid
Oleic acid
Palmitic acid
Stearic acid
Explanation - Linoleic acid (omega‑6) is abundant in plant membranes.
Correct answer is: Linoleic acid
Q.149 Which enzyme is responsible for the hydrolysis of cellobiose into glucose molecules?
Cellulase
Lactase
Maltase
Sucrase
Explanation - Cellulase cleaves β‑1,4 linkages in cellulose.
Correct answer is: Cellulase
Q.150 Which of the following is a key component of the human skin’s protective barrier?
Ceramides
Phosphatidylserine
Sphingomyelin
Cardiolipin
Explanation - Ceramides help form the barrier in the stratum corneum.
Correct answer is: Ceramides
Q.151 Which of the following lipids is a major component of the human brain’s myelin sheath?
Sphingomyelin
Cholesterol
Phosphatidylcholine
Cardiolipin
Explanation - Sphingomyelin is abundant in myelin.
Correct answer is: Sphingomyelin
Q.152 Which of the following is a key enzyme in the breakdown of glycogen during exercise?
Glycogen synthase
Glycogen phosphorylase
Phosphofructokinase
Hexokinase
Explanation - Glycogen phosphorylase catalyzes glycogen degradation.
Correct answer is: Glycogen phosphorylase
Q.153 Which of the following is NOT a function of carbohydrates in biological systems?
Energy storage
Cell‑cell communication
Catalysis
Structural support
Explanation - Carbohydrates generally do not act as catalysts; enzymes do.
Correct answer is: Catalysis