Here below some basic MCQ’s about “Biomolecules” chapter with answer which is explained in details. let’s check one by one which is given below.
MCQ 1:
Which of the following is a structural polysaccharide?
A) Starch
B) Glycogen
C) Cellulose
D) Sucrose
Answer: C) Cellulose
Explanation: Cellulose is a structural polysaccharide found in the cell walls of plants, providing rigidity and strength. Starch and glycogen are storage polysaccharides, while sucrose is a disaccharide.
MCQ 2:
Which of the following amino acids is classified as essential?
A) Alanine
B) Glutamine
C) Valine
D) Serine
Answer: C) Valine
Explanation: Essential amino acids cannot be synthesized by the body and must be obtained through diet. Valine is one of the essential amino acids, while alanine, glutamine, and serine are non-essential.
MCQ 3:
What type of bond links amino acids together in proteins?
A) Hydrogen bonds
B) Ionic bonds
C) Peptide bonds
D) Disulfide bonds
Answer: C) Peptide bonds
Explanation: Peptide bonds form between the amino group of one amino acid and the carboxyl group of another, linking amino acids together in a protein chain. Other bonds play roles in protein folding but do not link amino acids directly.
MCQ 4:
Which of the following biomolecules is primarily responsible for storing genetic information?
A) Proteins
B) Carbohydrates
C) Lipids
D) Nucleic acids
Answer: D) Nucleic acids
Explanation: Nucleic acids, such as DNA and RNA, are responsible for storing and transmitting genetic information. Proteins perform various functions, while carbohydrates and lipids have different roles in energy storage and membrane structure.
MCQ 5:
Lipids are primarily characterized by which of the following properties?
A) Soluble in water
B) Insoluble in organic solvents
C) Nonpolar nature
D) High molecular weight
Answer: C) Nonpolar nature
Explanation: Lipids are primarily nonpolar and hydrophobic, making them insoluble in water but soluble in organic solvents. This characteristic is crucial for their role in forming cell membranes.
MCQ 6:
Which of the following is NOT a function of proteins?
A) Catalyzing biochemical reactions
B) Providing energy storage
C) Serving as structural components
D) Transporting molecules
Answer: B) Providing energy storage
Explanation: While proteins can be used for energy if necessary, their primary roles include catalyzing reactions (enzymes), structural support (e.g., collagen), and transport (e.g., hemoglobin). Energy storage is primarily the role of carbohydrates and fats.
MCQ 7:
Which vitamin is a coenzyme for the carboxylation of substrates in metabolic pathways?
A) Vitamin C
B) Vitamin B6
C) Vitamin K
D) Vitamin B12
Answer: C) Vitamin K
Explanation: Vitamin K plays a crucial role in carboxylating certain proteins required for blood clotting. Vitamin B6 is involved in amino acid metabolism, Vitamin C is an antioxidant, and Vitamin B12 is vital for red blood cell formation.
MCQ 8:
Which of the following is a saturated fatty acid?
A) Oleic acid
B) Linoleic acid
C) Stearic acid
D) Palmitoleic acid
Answer: C) Stearic acid
Explanation: Stearic acid is a saturated fatty acid, meaning it has no double bonds between carbon atoms. Oleic acid and palmitoleic acid are unsaturated, containing one or more double bonds, while linoleic acid is a polyunsaturated fatty acid.
MCQ 9:
What type of bond is responsible for the secondary structure of proteins?
A) Ionic bonds
B) Hydrogen bonds
C) Peptide bonds
D) Van der Waals forces
Answer: B) Hydrogen bonds
Explanation: The secondary structure of proteins, such as alpha helices and beta sheets, is primarily stabilized by hydrogen bonds between the backbone amine and carbonyl groups of the polypeptide chain.
MCQ 10:
Which of the following carbohydrates is a disaccharide?
A) Glucose
B) Fructose
C) Sucrose
D) Cellulose
Answer: C) Sucrose
Explanation: Sucrose is a disaccharide composed of glucose and fructose. Glucose and fructose are monosaccharides, while cellulose is a polysaccharide.
MCQ 11:
Which molecule serves as the primary energy currency of the cell?
A) DNA
B) RNA
C) ATP
D) GTP
Answer: C) ATP
Explanation: ATP (adenosine triphosphate) is known as the primary energy currency of the cell, providing energy for various cellular processes. DNA and RNA are nucleic acids, while GTP is another energy molecule, less commonly used than ATP.
MCQ 12:
Which of the following is NOT a function of carbohydrates?
A) Energy storage
B) Structural support
C) Enzyme catalysis
D) Cell recognition
Answer: C) Enzyme catalysis
Explanation: While carbohydrates play important roles in energy storage, structural support, and cell recognition, enzyme catalysis is primarily the role of proteins.
MCQ 13:
Which type of lipid is primarily responsible for forming the cell membrane?
A) Phospholipids
B) Steroids
C) Triglycerides
D) Waxes
Answer: A) Phospholipids
Explanation: Phospholipids are the main component of cell membranes, forming a bilayer that provides structure and regulates what enters and leaves the cell. Triglycerides are for energy storage, steroids have signaling roles, and waxes provide protection.
MCQ 14:
Which of the following biomolecules contains the genetic information of an organism?
A) RNA
B) Proteins
C) Lipids
D) Carbohydrates
Answer: A) RNA
Explanation: RNA carries genetic information in certain viruses and is also involved in protein synthesis. While DNA is the primary genetic material in most organisms, RNA also plays essential roles in genetics.
MCQ 15:
Which of the following amino acids contains a sulfur atom?
A) Cysteine
B) Glutamate
C) Aspartate
D) Serine
Answer: A) Cysteine
Explanation: Cysteine is the amino acid that contains a sulfur atom in its side chain, which allows it to form disulfide bonds, crucial for protein structure.
MCQ 16:
Which of the following is a function of nucleotides besides serving as building blocks for nucleic acids?
A) Energy transfer
B) Structural support
C) Catalytic activity
D) Insulation
Answer: A) Energy transfer
Explanation: Nucleotides like ATP are involved in energy transfer within the cell. They do not provide structural support or insulation, nor are they primarily involved in catalytic activity (which is the role of enzymes).
MCQ 17:
Which of the following molecules is a product of the hydrolysis of starch?
A) Cellulose
B) Sucrose
C) Maltose
D) Glucose
Answer: C) Maltose
Explanation: Hydrolysis of starch, a polysaccharide, results in maltose, which is a disaccharide made of two glucose units. Further hydrolysis of maltose can yield glucose.
MCQ 18:
Which of the following proteins has a quaternary structure?
A) Myoglobin
B) Hemoglobin
C) Insulin
D) Keratin
Answer: B) Hemoglobin
Explanation: Hemoglobin has a quaternary structure consisting of four polypeptide subunits. Myoglobin has a tertiary structure, insulin is a dimer (two chains), and keratin is primarily fibrous and forms a different type of structure.
MCQ 19:
What is the basic structural unit of proteins?
A) Nucleotides
B) Amino acids
C) Fatty acids
D) Monosaccharides
Answer: B) Amino acids
Explanation: Amino acids are the basic building blocks of proteins, linked by peptide bonds to form polypeptide chains. Nucleotides are the building blocks of nucleic acids, while fatty acids and monosaccharides are components of lipids and carbohydrates, respectively.
MCQ 20:
Which of the following is a feature of enzymes?
A) They increase the activation energy of reactions.
B) They are consumed in the reaction.
C) They are specific to substrates.
D) They function at any temperature.
Answer: C) They are specific to substrates.
Explanation: Enzymes are highly specific to their substrates and catalyze reactions without being consumed in the process. They lower the activation energy of reactions, and their activity can be affected by temperature.
MCQ 21:
Which of the following is the primary component of cell membranes?
A) Carbohydrates
B) Proteins
C) Nucleic acids
D) Phospholipids
Answer: D) Phospholipids
Explanation: Phospholipids form the fundamental structure of cell membranes, creating a bilayer that separates the interior of the cell from the external environment. Carbohydrates and proteins play supporting roles, while nucleic acids are not structural components of membranes.
MCQ 22:
Which type of RNA carries the genetic information from DNA to the ribosome?
A) rRNA
B) tRNA
C) mRNA
D) hnRNA
Answer: C) mRNA
Explanation: Messenger RNA (mRNA) carries the genetic code from DNA to the ribosome, where proteins are synthesized. Ribosomal RNA (rRNA) is part of the ribosome structure, and transfer RNA (tRNA) brings amino acids during protein synthesis.
MCQ 23:
What is the function of enzymes in biochemical reactions?
A) To change the equilibrium of the reaction
B) To increase the activation energy
C) To speed up the reaction rate
D) To become products of the reaction
Answer: C) To speed up the reaction rate
Explanation: Enzymes catalyze biochemical reactions by lowering the activation energy, thus increasing the reaction rate. They do not change the equilibrium of the reaction and are not consumed in the process.
MCQ 24:
Which of the following is an example of a heteropolymer?
A) Glycogen
B) Cellulose
C) DNA
D) Starch
Answer: C) DNA
Explanation: DNA is a heteropolymer because it is composed of different types of nucleotides (adenine, thymine, cytosine, guanine). Glycogen and starch are homopolymers of glucose, while cellulose is a homopolymer made of glucose units.
MCQ 25:
Which of the following vitamins is primarily involved in vision?
A) Vitamin A
B) Vitamin D
C) Vitamin E
D) Vitamin K
Answer: A) Vitamin A
Explanation: Vitamin A is essential for vision, particularly for the synthesis of rhodopsin, a pigment in the retina. Vitamins D, E, and K have different roles in the body, such as calcium metabolism and antioxidant functions.
MCQ 26:
What type of bond forms between the sugar and phosphate groups in nucleic acids?
A) Hydrogen bonds
B) Peptide bonds
C) Glycosidic bonds
D) Phosphodiester bonds
Answer: D) Phosphodiester bonds
Explanation: Phosphodiester bonds link the sugar of one nucleotide to the phosphate group of another in nucleic acids, forming the backbone of DNA and RNA. Hydrogen bonds occur between base pairs, and glycosidic bonds link sugars in carbohydrates.
MCQ 27:
Which of the following amino acids is a precursor for the neurotransmitter serotonin?
A) Tyrosine
B) Tryptophan
C) Phenylalanine
D) Glutamate
Answer: B) Tryptophan
Explanation: Tryptophan is the amino acid precursor for serotonin, a neurotransmitter that regulates mood. Tyrosine and phenylalanine are precursors for dopamine and norepinephrine, while glutamate is an important neurotransmitter itself.
MCQ 28:
Which of the following is a primary structure of proteins?
A) Alpha-helix
B) Beta-sheet
C) Polypeptide chain
D) Disulfide bridge
Answer: C) Polypeptide chain
Explanation: The primary structure of proteins refers to the linear sequence of amino acids in a polypeptide chain. Alpha-helices and beta-sheets are forms of secondary structure, while disulfide bridges are involved in tertiary and quaternary structures.
MCQ 29:
Which type of lipid is important for long-term energy storage?
A) Phospholipids
B) Steroids
C) Triglycerides
D) Glycolipids
Answer: C) Triglycerides
Explanation: Triglycerides are the main form of stored energy in animals and plants. They consist of three fatty acids attached to a glycerol molecule. Phospholipids and glycolipids are important for cell membranes, and steroids have various functions in signaling.
MCQ 30:
Which of the following molecules acts as an energy carrier in the cell?
A) DNA
B) RNA
C) ATP
D) Protein
Answer: C) ATP
Explanation: ATP (adenosine triphosphate) is the primary energy carrier in cells, providing energy for various biochemical reactions. DNA and RNA are genetic materials, while proteins perform a wide range of functions.
MCQ 31:
Which of the following is a characteristic of unsaturated fatty acids?
A) They are solid at room temperature.
B) They contain one or more double bonds.
C) They are derived from animal fats.
D) They have higher melting points than saturated fats.
Answer: B) They contain one or more double bonds.
Explanation: Unsaturated fatty acids contain one or more double bonds between carbon atoms, making them usually liquid at room temperature. Saturated fats are solid at room temperature and typically come from animal sources.
MCQ 32:
Which of the following is a function of cholesterol in the cell membrane?
A) Energy storage
B) Hormone synthesis
C) Maintaining membrane fluidity
D) Genetic information storage
Answer: C) Maintaining membrane fluidity
Explanation: Cholesterol is a crucial component of cell membranes that helps maintain fluidity, allowing the membrane to remain flexible at various temperatures. It is also a precursor for steroid hormones but does not store energy or genetic information.
MCQ 33:
Which of the following molecules is a type of glycoprotein?
A) Insulin
B) Hemoglobin
C) Antibodies
D) Collagen
Answer: C) Antibodies
Explanation: Antibodies are glycoproteins that play a crucial role in the immune response. Insulin is a peptide hormone, hemoglobin is a protein that carries oxygen, and collagen is a structural protein.
MCQ 34:
Which component of nucleotides differs between DNA and RNA?
A) Sugar
B) Nitrogenous base
C) Phosphate group
D) All of the above
Answer: A) Sugar
Explanation: The sugar component differs between DNA (deoxyribose) and RNA (ribose). Both types of nucleotides contain phosphate groups and can have different nitrogenous bases (thymine in DNA vs. uracil in RNA).
MCQ 35:
What is the role of ribosomes in a cell?
A) Energy production
B) Protein synthesis
C) Lipid storage
D) DNA replication
Answer: B) Protein synthesis
Explanation: Ribosomes are the cellular machinery responsible for synthesizing proteins by translating mRNA into amino acid sequences. They do not directly participate in energy production, lipid storage, or DNA replication.
MCQ 36:
Which type of carbohydrate can be digested by humans?
A) Cellulose
B) Starch
C) Chitin
D) Glycogen
Answer: B) Starch
Explanation: Starch is a digestible carbohydrate found in plants, composed of glucose units. Humans cannot digest cellulose due to the beta-glycosidic bonds, and chitin is a structural polysaccharide in fungi and arthropods. Glycogen is digestible, but it is primarily a storage form in animals.
MCQ 37:
Which of the following is a nonpolar amino acid?
A) Aspartate
B) Glutamate
C) Phenylalanine
D) Lysine
Answer: C) Phenylalanine
Explanation: Phenylalanine is a nonpolar amino acid due to its hydrophobic side chain. Aspartate and glutamate are polar and negatively charged, while lysine is polar and positively charged.
MCQ 38:
What is the primary function of enzymes in biochemical reactions?
A) To decrease the reaction rate
B) To provide energy
C) To lower the activation energy
D) To change the products of the reaction
Answer: C) To lower the activation energy
Explanation: Enzymes catalyze reactions by lowering the activation energy required for the reaction to proceed, thereby increasing the reaction rate. They do not provide energy or alter the products of the reaction.
MCQ 39:
Which of the following fatty acids is essential and must be obtained from the diet?
A) Stearic acid
B) Palmitic acid
C) Linoleic acid
D) Myristic acid
Answer: C) Linoleic acid
Explanation: Linoleic acid is an essential fatty acid that humans must obtain from their diet. Stearic, palmitic, and myristic acids can be synthesized by the body.
MCQ 40:
Which of the following is a key characteristic of enzymes?
A) They can work in any environment.
B) They can be reused multiple times.
C) They are permanently altered after the reaction.
D) They increase the equilibrium constant of the reaction.
Answer: B) They can be reused multiple times.
Explanation: Enzymes can be reused multiple times after catalyzing a reaction, as they are not consumed in the process. They work under specific conditions and do not change the equilibrium constant.
MCQ 41:
Which of the following is a storage form of glucose in animals?
A) Cellulose
B) Starch
C) Glycogen
D) Chitin
Answer: C) Glycogen
Explanation: Glycogen is the storage form of glucose in animals, primarily found in the liver and muscle tissues. Cellulose and starch are forms of carbohydrates in plants, while chitin is a structural polysaccharide in fungi and exoskeletons of arthropods.
MCQ 42:
Which amino acid contains an aromatic ring?
A) Valine
B) Glycine
C) Phenylalanine
D) Proline
Answer: C) Phenylalanine
Explanation: Phenylalanine contains an aromatic ring in its side chain, making it an aromatic amino acid. Valine, glycine, and proline do not have aromatic structures.
MCQ 43:
Which of the following vitamins is fat-soluble?
A) Vitamin B12
B) Vitamin C
C) Vitamin A
D) Vitamin B6
Answer: C) Vitamin A
Explanation: Vitamin A is a fat-soluble vitamin, while vitamins B12, C, and B6 are water-soluble. Fat-soluble vitamins are stored in body fat and can be utilized as needed.
MCQ 44:
What type of interaction stabilizes the tertiary structure of proteins?
A) Peptide bonds
B) Hydrogen bonds
C) Ionic interactions
D) All of the above
Answer: D) All of the above
Explanation: The tertiary structure of proteins is stabilized by various interactions, including peptide bonds, hydrogen bonds, ionic interactions, hydrophobic interactions, and disulfide bridges.
MCQ 45:
Which of the following is a component of ATP?
A) Ribose, adenine, and three phosphate groups
B) Deoxyribose, thymine, and three phosphate groups
C) Ribose, guanine, and two phosphate groups
D) Ribose, adenine, and one phosphate group
Answer: A) Ribose, adenine, and three phosphate groups
Explanation: ATP (adenosine triphosphate) consists of ribose sugar, adenine base, and three phosphate groups. It serves as the main energy currency of the cell.
MCQ 46:
Which of the following is a characteristic of enzymes?
A) They can be denatured by changes in pH and temperature.
B) They change the equilibrium of the reaction.
C) They are always proteins.
D) They require coenzymes for all reactions.
Answer: A) They can be denatured by changes in pH and temperature.
Explanation: Enzymes can be denatured by extreme changes in pH and temperature, which affect their structure and function. Not all enzymes are proteins (some are RNA), and they do not change the equilibrium of reactions.
MCQ 47:
What is the primary structure of DNA?
A) A double helix
B) A single strand
C) A linear sequence of nucleotides
D) A three-dimensional folded structure
Answer: C) A linear sequence of nucleotides
Explanation: The primary structure of DNA refers to its linear sequence of nucleotides, which includes the sugar, phosphate, and nitrogenous bases. The double helix is the secondary structure.
MCQ 48:
Which of the following carbohydrates is NOT digestible by humans?
A) Starch
B) Glycogen
C) Cellulose
D) Sucrose
Answer: C) Cellulose
Explanation: Humans cannot digest cellulose due to the beta-glycosidic bonds between glucose units. Starch and glycogen are digestible, and sucrose is a disaccharide that can be broken down.
MCQ 49:
Which process synthesizes ATP using a proton gradient across the inner mitochondrial membrane?
A) Glycolysis
B) Krebs cycle
C) Oxidative phosphorylation
D) Fermentation
Answer: C) Oxidative phosphorylation
Explanation: Oxidative phosphorylation synthesizes ATP using a proton gradient created by the electron transport chain across the inner mitochondrial membrane. Glycolysis and the Krebs cycle produce less ATP, while fermentation occurs in anaerobic conditions.
MCQ 50:
What type of bond links monosaccharides to form disaccharides?
A) Peptide bond
B) Glycosidic bond
C) Ionic bond
D) Hydrogen bond
Answer: B) Glycosidic bond
Explanation: Glycosidic bonds link monosaccharides together to form disaccharides and polysaccharides. Peptide bonds link amino acids, while ionic and hydrogen bonds play different roles in molecular interactions.
MCQ 51:
Which amino acid is known for having a side chain that can form disulfide bonds?
A) Cysteine
B) Methionine
C) Tryptophan
D) Serine
Answer: A) Cysteine
Explanation: Cysteine contains a thiol (-SH) group in its side chain, allowing it to form disulfide bonds with other cysteine residues, which are important for stabilizing protein structure.
MCQ 52:
Which of the following describes the role of chaperone proteins?
A) They catalyze reactions.
B) They help in DNA replication.
C) They assist in protein folding.
D) They transport molecules across membranes.
Answer: C) They assist in protein folding.
Explanation: Chaperone proteins assist in the proper folding of other proteins, ensuring they achieve their functional three-dimensional structures. They do not catalyze reactions, replicate DNA, or transport molecules.
MCQ 53:
Which of the following is a non-reducing sugar?
A) Glucose
B) Fructose
C) Sucrose
D) Maltose
Answer: C) Sucrose
Explanation: Sucrose is a non-reducing sugar because it does not have a free aldehyde or ketone group that can reduce other compounds. Glucose, fructose, and maltose can act as reducing sugars.
MCQ 54:
Which type of fatty acid is characterized by having multiple double bonds?
A) Saturated fatty acid
B) Monounsaturated fatty acid
C) Polyunsaturated fatty acid
D) Trans fatty acid
Answer: C) Polyunsaturated fatty acid
Explanation: Polyunsaturated fatty acids contain multiple double bonds in their carbon chain, while saturated fatty acids have no double bonds, and monounsaturated fatty acids have one double bond.
MCQ 55:
Which of the following molecules is a primary component of the plasma membrane?
A) Phospholipids
B) Steroids
C) Proteins
D) Glycogen
Answer: A) Phospholipids
Explanation: Phospholipids form the fundamental structure of the plasma membrane, creating a bilayer. Proteins and steroids are also present but are not the primary structural components.
MCQ 56:
Which of the following vitamins is involved in collagen synthesis?
A) Vitamin A
B) Vitamin C
C) Vitamin D
D) Vitamin K
Answer: B) Vitamin C
Explanation: Vitamin C is crucial for collagen synthesis, as it acts as a cofactor for the enzymes involved in collagen production. Other vitamins have different roles in the body.
MCQ 57:
Which of the following processes occurs in the cytoplasm of eukaryotic cells?
A) Krebs cycle
B) Oxidative phosphorylation
C) Glycolysis
D) Electron transport chain
Answer: C) Glycolysis
Explanation: Glycolysis occurs in the cytoplasm of eukaryotic cells, breaking down glucose into pyruvate. The Krebs cycle and oxidative phosphorylation occur in the mitochondria, and the electron transport chain is also mitochondrial.
MCQ 58:
Which of the following amino acids can be classified as polar?
A) Alanine
B) Valine
C) Asparagine
D) Phenylalanine
Answer: C) Asparagine
Explanation: Asparagine is a polar amino acid due to its side chain containing an amide group, which can form hydrogen bonds. Alanine and valine are nonpolar, and phenylalanine is aromatic.
MCQ 59:
What is the primary role of the ribosome in the cell?
A) Lipid synthesis
B) Protein synthesis
C) Energy production
D) DNA replication
Answer: B) Protein synthesis
Explanation: Ribosomes are the cellular structures responsible for synthesizing proteins by translating mRNA into amino acid sequences. They do not perform lipid synthesis, energy production, or DNA replication.
MCQ 60:
Which of the following is a function of lipids?
A) Energy storage
B) Insulation
C) Cell membrane formation
D) All of the above
Answer: D) All of the above
Explanation: Lipids serve multiple functions, including energy storage, insulation, and forming cell membranes. They are diverse biomolecules with various roles in biological systems.
MCQ 61:
Which of the following components is NOT part of a nucleotide?
A) Phosphate group
B) Sugar
C) Amino acid
D) Nitrogenous base
Answer: C) Amino acid
Explanation: A nucleotide consists of a phosphate group, a sugar (ribose in RNA, deoxyribose in DNA), and a nitrogenous base. Amino acids are the building blocks of proteins, not nucleotides.
MCQ 62:
Which of the following is a type of secondary structure found in proteins?
A) Disulfide bridge
B) Alpha-helix
C) Peptide bond
D) Glycosidic bond
Answer: B) Alpha-helix
Explanation: The alpha-helix is a common type of secondary structure in proteins, stabilized by hydrogen bonds. Disulfide bridges are part of tertiary structure, while peptide bonds link amino acids, and glycosidic bonds link carbohydrates.
MCQ 63:
Which of the following is an example of a polysaccharide?
A) Sucrose
B) Lactose
C) Starch
D) Fructose
Answer: C) Starch
Explanation: Starch is a polysaccharide composed of many glucose units and is used for energy storage in plants. Sucrose and lactose are disaccharides, while fructose is a monosaccharide.
MCQ 64:
What type of bond is primarily responsible for the stability of DNA’s double helix structure?
A) Ionic bonds
B) Hydrogen bonds
C) Covalent bonds
D) Peptide bonds
Answer: B) Hydrogen bonds
Explanation: Hydrogen bonds between complementary nitrogenous bases stabilize the double helix structure of DNA. Covalent bonds link the sugar and phosphate backbone, while ionic and peptide bonds are not involved in DNA structure.
MCQ 65:
Which of the following is an example of an essential amino acid?
A) Alanine
B) Glycine
C) Leucine
D) Serine
Answer: C) Leucine
Explanation: Leucine is an essential amino acid that must be obtained from the diet, while alanine, glycine, and serine can be synthesized by the body.
MCQ 66:
Which biomolecule serves as the genetic material in most organisms?
A) RNA
B) Proteins
C) DNA
D) Carbohydrates
Answer: C) DNA
Explanation: DNA (deoxyribonucleic acid) serves as the genetic material in most organisms, storing and transmitting genetic information. RNA plays a role in protein synthesis but is not the primary genetic material.
MCQ 67:
Which type of lipid is responsible for hormone production?
A) Triglycerides
B) Phospholipids
C) Steroids
D) Waxes
Answer: C) Steroids
Explanation: Steroids are a type of lipid involved in hormone production, including hormones like estrogen and testosterone. Triglycerides are for energy storage, phospholipids make up cell membranes, and waxes serve protective roles.
MCQ 68:
Which of the following enzymes breaks down carbohydrates?
A) Lipase
B) Protease
C) Amylase
D) Nuclease
Answer: C) Amylase
Explanation: Amylase is the enzyme responsible for breaking down carbohydrates, specifically starches into sugars. Lipase breaks down lipids, protease breaks down proteins, and nuclease breaks down nucleic acids.
MCQ 69:
What is the primary function of hemoglobin?
A) Energy storage
B) Oxygen transport
C) Immune response
D) Hormone regulation
Answer: B) Oxygen transport
Explanation: Hemoglobin is a protein in red blood cells that transports oxygen from the lungs to the tissues and returns carbon dioxide to the lungs. It does not store energy or regulate hormones.
MCQ 70:
Which of the following best describes a noncompetitive inhibitor?
A) Binds to the active site of an enzyme
B) Binds to a site other than the active site
C) Can be overcome by increasing substrate concentration
D) Permanently alters the enzyme
Answer: B) Binds to a site other than the active site
Explanation: A noncompetitive inhibitor binds to an enzyme at a site other than the active site, reducing enzyme activity regardless of substrate concentration. It does not permanently alter the enzyme and cannot be overcome by increasing substrate concentration.
MCQ 71:
Which of the following molecules are involved in the structure of ribosomes?
A) DNA
B) mRNA
C) rRNA
D) tRNA
Answer: C) rRNA
Explanation: Ribosomal RNA (rRNA) is a key component of ribosomes, where protein synthesis occurs. DNA carries genetic information, mRNA conveys that information to the ribosome, and tRNA brings amino acids.
MCQ 72:
Which of the following is a characteristic of enzymes?
A) They increase the energy of activation.
B) They are highly specific to their substrates.
C) They are consumed during the reaction.
D) They require heat for activity.
Answer: B) They are highly specific to their substrates.
Explanation: Enzymes are highly specific to their substrates, allowing them to catalyze particular reactions efficiently. They lower the activation energy, are not consumed in the reaction, and do not require excessive heat for activity.
MCQ 73:
Which of the following is an indicator of the presence of starch?
A) Biuret reagent
B) Benedict’s solution
C) Iodine solution
D) Sudan III
Answer: C) Iodine solution
Explanation: Iodine solution turns blue-black in the presence of starch. Biuret reagent tests for proteins, Benedict’s solution tests for reducing sugars, and Sudan III is a lipid stain.
MCQ 74:
Which of the following amino acids has a side chain that can be phosphorylated?
A) Serine
B) Valine
C) Phenylalanine
D) Glycine
Answer: A) Serine
Explanation: Serine contains a hydroxyl group in its side chain, allowing it to be phosphorylated, which is important for regulating protein activity. Valine, phenylalanine, and glycine do not have this capability.
MCQ 75:
Which of the following describes a saturated fatty acid?
A) Contains one or more double bonds
B) Solid at room temperature
C) Liquid at room temperature
D) Derived only from plant sources
Answer: B) Solid at room temperature
Explanation: Saturated fatty acids have no double bonds between carbon atoms, which makes them solid at room temperature. Unsaturated fatty acids contain one or more double bonds and are usually liquid at room temperature.
MCQ 76:
Which of the following processes converts pyruvate into lactate?
A) Oxidative phosphorylation
B) Fermentation
C) Krebs cycle
D) Glycolysis
Answer: B) Fermentation
Explanation: Fermentation is the process that converts pyruvate into lactate (in muscles) or ethanol (in yeast) under anaerobic conditions. Glycolysis breaks down glucose into pyruvate, while the Krebs cycle and oxidative phosphorylation occur in aerobic respiration.
MCQ 77:
Which vitamin is primarily involved in the synthesis of coenzyme A?
A) Vitamin B1
B) Vitamin B5
C) Vitamin B2
D) Vitamin B12
Answer: B) Vitamin B5
Explanation: Vitamin B5 (pantothenic acid) is a precursor to coenzyme A, which is essential for fatty acid metabolism and the Krebs cycle. The other B vitamins have different roles in metabolism.
MCQ 78:
Which of the following structures represents the tertiary structure of proteins?
A) Linear chain of amino acids
B) Alpha-helix and beta-sheet
C) Three-dimensional folding
D) Dimeric arrangement
Answer: C) Three-dimensional folding
Explanation: The tertiary structure of proteins refers to their three-dimensional folding, which results from interactions among side chains. The linear chain is primary structure, and alpha-helices and beta-sheets are secondary structures.
MCQ 79:
Which of the following statements about enzymes is true?
A) They are made of nucleic acids.
B) They can be denatured by extreme temperatures.
C) They are only active at high pH levels.
D) They change the equilibrium constant of a reaction.
Answer: B) They can be denatured by extreme temperatures.
Explanation: Enzymes are primarily proteins, and they can be denatured by extreme temperatures and pH levels, which can affect their function. They do not change the equilibrium constant of reactions and can function in a range of pH levels.
MCQ 80:
Which of the following is a function of carbohydrates?
A) Energy source
B) Structural support
C) Cell recognition
D) All of the above
Answer: D) All of the above
Explanation: Carbohydrates serve multiple functions, including acting as an energy source, providing structural support (like cellulose in plants), and facilitating cell recognition through glycoproteins and glycolipids.
MCQ 81:
Which of the following is a characteristic of RNA?
A) Contains thymine
B) Double-stranded
C) Ribose sugar
D) Only found in the nucleus
Answer: C) Ribose sugar
Explanation: RNA contains ribose sugar and typically exists as a single-stranded molecule. It contains uracil instead of thymine and can be found in both the nucleus and cytoplasm.
MCQ 82:
What is the main function of enzymes in biochemical reactions?
A) To act as substrates
B) To increase the rate of reaction
C) To change the products formed
D) To require high temperatures
Answer: B) To increase the rate of reaction
Explanation: Enzymes are biological catalysts that increase the rate of biochemical reactions by lowering the activation energy required, without changing the products or needing high temperatures.
MCQ 83:
Which of the following is a property of lipids?
A) They are soluble in water.
B) They are hydrophobic.
C) They form polymers.
D) They contain nitrogen.
Answer: B) They are hydrophobic.
Explanation: Lipids are primarily hydrophobic and do not mix well with water. They do not form polymers like carbohydrates or proteins and may contain carbon, hydrogen, and sometimes oxygen but not nitrogen.
MCQ 84:
Which biomolecule is primarily responsible for energy storage in plants?
A) Glycogen
B) Starch
C) Cellulose
D) Chitin
Answer: B) Starch
Explanation: Starch is the main energy storage carbohydrate in plants, while glycogen is found in animals, cellulose provides structural support, and chitin is found in fungal cell walls and exoskeletons of arthropods.
MCQ 85:
Which amino acid is the starting point for protein synthesis in eukaryotic cells?
A) Methionine
B) Serine
C) Alanine
D) Cysteine
Answer: A) Methionine
Explanation: Methionine is the first amino acid incorporated during the synthesis of proteins in eukaryotic cells, due to its role as the initiator amino acid for translation.
MCQ 86:
Which of the following statements is true regarding competitive inhibitors?
A) They bind to the enzyme’s active site.
B) They can be overcome by increasing substrate concentration.
C) They permanently alter the enzyme’s structure.
D) Both A and B.
Answer: D) Both A and B.
Explanation: Competitive inhibitors bind to the active site of an enzyme, competing with the substrate. Their effects can be overcome by increasing substrate concentration, but they do not permanently alter the enzyme.
MCQ 87:
What is the primary function of cholesterol in the body?
A) Energy storage
B) Hormone synthesis
C) Structural component of cell membranes
D) All of the above
Answer: D) All of the above
Explanation: Cholesterol plays multiple roles in the body, including being a structural component of cell membranes, a precursor for hormone synthesis, and involved in energy storage.
MCQ 88:
Which of the following best describes the term “hydrophobic”?
A) Attracted to water
B) Repelled by water
C) Soluble in water
D) Contains polar bonds
Answer: B) Repelled by water
Explanation: Hydrophobic substances do not interact well with water and tend to be repelled by it. This characteristic is typical of many lipids.
MCQ 89:
Which type of RNA carries the genetic code from DNA to the ribosome?
A) rRNA
B) mRNA
C) tRNA
D) snRNA
Answer: B) mRNA
Explanation: Messenger RNA (mRNA) carries the genetic information from DNA to the ribosome for protein synthesis. Ribosomal RNA (rRNA) forms part of the ribosome, while transfer RNA (tRNA) brings amino acids to the ribosome.
MCQ 90:
Which of the following compounds is a result of the breakdown of fatty acids?
A) Acetyl CoA
B) Pyruvate
C) Glucose
D) Glycerol
Answer: A) Acetyl CoA
Explanation: The breakdown of fatty acids (beta-oxidation) produces acetyl CoA, which can enter the Krebs cycle. Pyruvate is produced from glucose, and glycerol is a component of triglycerides.
MCQ 91:
What type of bond forms between amino acids in a protein?
A) Ionic bond
B) Hydrogen bond
C) Peptide bond
D) Glycosidic bond
Answer: C) Peptide bond
Explanation: Peptide bonds are covalent bonds that link amino acids together to form proteins. Ionic bonds, hydrogen bonds, and glycosidic bonds serve different roles in molecular interactions.
MCQ 92:
Which of the following is a characteristic of chitin?
A) It is a component of plant cell walls.
B) It is a polysaccharide.
C) It is soluble in water.
D) It is a source of energy.
Answer: B) It is a polysaccharide.
Explanation: Chitin is a polysaccharide that serves as a structural component in the exoskeletons of arthropods and the cell walls of fungi. It is not found in plant cell walls and is not a soluble source of energy.
MCQ 93:
Which vitamin is known for its role in vision and skin health?
A) Vitamin A
B) Vitamin B12
C) Vitamin C
D) Vitamin D
Answer: A) Vitamin A
Explanation: Vitamin A is essential for vision, particularly in low-light conditions, and is important for skin health and immune function. The other vitamins have different roles.
MCQ 94:
Which of the following molecules serves as the primary energy currency of the cell?
A) ADP
B) AMP
C) ATP
D) NADH
Answer: C) ATP
Explanation: Adenosine triphosphate (ATP) is the primary energy currency of the cell, used to power various cellular processes. ADP (adenosine diphosphate) and AMP (adenosine monophosphate) are lower-energy forms, while NADH is a carrier of electrons in cellular respiration.
MCQ 95:
Which type of fatty acid is associated with heart health and is found in fish oil?
A) Saturated fatty acids
B) Monounsaturated fatty acids
C) Polyunsaturated fatty acids
D) Trans fatty acids
Answer: C) Polyunsaturated fatty acids
Explanation: Polyunsaturated fatty acids, particularly omega-3 fatty acids found in fish oil, are beneficial for heart health. Saturated fats are linked to heart disease, while trans fats are harmful.
MCQ 96:
Which type of bond is found in the secondary structure of proteins?
A) Peptide bonds
B) Ionic bonds
C) Hydrogen bonds
D) Disulfide bonds
Answer: C) Hydrogen bonds
Explanation: Hydrogen bonds stabilize the secondary structures of proteins, such as alpha-helices and beta-sheets. Peptide bonds link amino acids, while ionic and disulfide bonds contribute to tertiary structure.
MCQ 97:
What is the function of insulin in the body?
A) To increase blood glucose levels
B) To decrease blood glucose levels
C) To promote protein synthesis
D) To stimulate fat breakdown
Answer: B) To decrease blood glucose levels
Explanation: Insulin is a hormone produced by the pancreas that lowers blood glucose levels by promoting the uptake of glucose into cells and stimulating glycogen synthesis.
MCQ 98:
Which of the following describes an enzyme’s active site?
A) The region where substrate binds
B) The part of the enzyme that stabilizes the transition state
C) The location where allosteric regulation occurs
D) All of the above
Answer: D) All of the above
Explanation: The active site of an enzyme is where the substrate binds, and it plays a role in stabilizing the transition state. Allosteric regulation can also involve modifications at or near the active site.
MCQ 99:
What is the role of tRNA in protein synthesis?
A) To carry genetic information
B) To bring amino acids to the ribosome
C) To form part of the ribosomal structure
D) To catalyze peptide bond formation
Answer: B) To bring amino acids to the ribosome
Explanation: Transfer RNA (tRNA) transports specific amino acids to the ribosome, where they are added to the growing polypeptide chain during protein synthesis. mRNA carries genetic information, and rRNA forms part of the ribosome.
MCQ 100:
Which of the following is a function of nucleic acids?
A) Energy storage
B) Genetic information storage
C) Structural support
D) Catalysis
Answer: B) Genetic information storage
Explanation: Nucleic acids (DNA and RNA) are primarily responsible for storing and transmitting genetic information. They do not serve as energy storage, provide structural support, or act as catalysts (which is the role of proteins).
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