Our 1000+ MCQs focus on all topics of the Biochemistry subject, covering 100+ topics. This will help you to prepare for exams, contests, online tests, quizzes, viva-voce, interviews, and certifications. You can practice these MCQs chapter by chapter starting from the 1st chapter or you can jump to any chapter of your choice.
- Water Basics
- Amino Acids, Peptides and Proteins
- Three Dimensional Structure Of Proteins and Protein Function
- Enzymes, Carbohydrates and Gycobiology
- Nucleotides and Nucleic Acids
- DNA-Based Information Technologies
- Lipids, Biological Membranes and Transport
- Biosignalling
- Principles of Bioenergetics and Glycolysis
- Principles of Metabolic Regulation: Glucose and Glycogen
- Amino Acid Oxidation and the Production of Urea
- Oxidative Phosphorylation and Photophosphorylation
- Lipid Biosynthesis, Biosynthesis of Amino Acids, Nucleotides and Related Molecules
- Genes and Chromosomes
- DNA, RNA and Protein Metabolism
- Regulation of Gene Expression and Miscellaneous
1. Biochemistry MCQ on Water Basics
1. Which of the following makes water a liquid at room temperature?
a) Noncovalent interactions
b) Hydrogen bonds between water molecules
c) Van der Waals forces of attraction
d) Covalent bonding
View Answer
Explanation: The cohesive forces that keep the water a liquid at normal temperature are provided by hydrogen bonds between water molecules.
2. The heat of vaporization of water is ________
a) 540 Kj/g
b) 580 kJ/g
c) 1060 J/g
d) 600 kJ/g
View Answer
Explanation: The heat of vaporization of water is around 540 Kj/g.
3. The degree of ionization does not depend on which of the following parameter?
a) Nature of solvent
b) Temperature
c) Concentration
d) Current
View Answer
Explanation: Current has no effect on the degree of ionization. Temperature, solvent type, and concentration are the only variables.
4. Which of the following mixture in aqueous solution of equimolar concentration acts as a buffer solution?
a) NH4 OH(excess) + HCl
b) HNO3 + NaOH
c) CH3 COOH + NaOH(excess)
d) H2 SO4 + KOH
View Answer
Explanation: NH4 OH(excess) + HCl → NH4 Cl + H2O
So the mixture contains NH4 OH + NH4 Cl.
5. Based on which of the following enzymes Hydrolysis reactions are catalyzed?
a) Hydrolase
b) Oxidoreductase
c) Isomerase
d) Ligase
View Answer
Explanation: Food degradation and digestion are aided by hydrolases, which catalyze hydrolysis reactions.
The following table contains a complete set of multiple-choice questions and answers on weak interactions in an aqueous system, ionization of water, ph changes in biological systems, and water as a reactant.
2. Biochemistry Multiple Choice Question on Amino Acids, Peptides and Proteins
1. Which of the following is an imino acid?
a) Serine
b) Alanine
c) Glycine
d) Proline
View Answer
Explanation: Because it contains the –C = NH – OH group, proline is classified as a secondary amino acid, sometimes known as an imino acid.
2. Which of the following is a 39-residue hormone of the anterior pituitary gland?
a) Glucagon
b) Bradykinin
c) Corticotropin
d) Insulin
View Answer
Explanation: The anterior pituitary gland produces corticotropin, a 39-residue hormone that activates the adrenal cortex.
3. Which of the following statements is correct about column chromatography?
a) Resolution improves as column length increases
b) Mobile phase is a porous solid material kept in the column with appropriate chemical characteristics
c) Stationary phase is a buffered solution that percolates through the mobile phase
d) Large proteins exit the column faster than tiny proteins
View Answer
Explanation: As the length of the column grows longer, the entire protein band widens as it passes through it. Individual proteins eventually separate from one another, generating bands within the larger protein, and this separation grows as the column lengthens.
4. Who deduced the double-helical structure of DNA?
a) Watson and Francis Crick
b) Frederick Sanger
c) Anton van Leeuwenhoek
d) Mendel
View Answer
Explanation: The double-helical structure of DNA was discovered in 1953 by James D. Watson and Francis Crick, who postulated a structural basis for its accurate replication.
5. The amino acid sequences of thousands of different proteins from many species have been determined using principles first developed by?
a) Watson and Crick
b) Edman
c) Sanger
d) Mendel
View Answer
Explanation: The amino acid sequences of thousands of proteins from a variety of animals have been determined using Frederick Sanger’s ideas.
The following table contains a complete set of multiple-choice questions and answers on amino acids, peptides and proteins and its working, protein sequences, covalent structure of proteins.
3. Biochemistry MCQ on Three Dimensional Structure Of Proteins and Protein Function
1. The stability of an α-helix is not affected by which of the following?
a) Bulkiness
b) Occurrence of alanine and glycine residues
c) Electrostatic repulsion
d) Interaction between R groups spaced three residues apart
View Answer
Explanation: An α-helix’s stability is influenced by the presence of Proline and Glycine residues.
2. Which of the following is abundantly found in collagen?
a) Tryptophan
b) Alanine
c) Glycine
d) Serine
View Answer
Explanation: Each of the collagen peptide chain’s three amino acids is a glycine. As a result, it is a plentiful amino acid that is essential for collagen construction.
3. Which of the following is a function of chaperone protein?
a) It provides a template for how the proteins should fold
b) It degrades proteins that have folded properly
c) It degrades proteins that have folded improperly
d) It rescues proteins that have folded improperly and allowed them to refold properly
View Answer
Explanation: Molecular chaperons are proteins that interact with partially folded polypeptides in order to facilitate correct folding mechanisms.
4. The relationship between oxygen concentration and the fraction of binding sites occupied in myoglobin can best be described as ________
a) Linear with a positive slope
b) Hyperbolic
c) Parabolic
d) Linear with a negative slope
View Answer
Explanation: The equation θ=(pO2)/(pO2 +P50) is of the form y = x/(x+z) which describes hyperbola.
5. When compared to the first immune response to the same antigen, which of the following is not a hallmark of the secondary immune response?
a) Antibody is generated fast
b) Many antibodies is produced
c) Antibody is generated without T-cell help
d) Antibody produced has a greater affinity for the antigen
View Answer
Explanation: The features of the secondary immune response are:
i) Antibodies are produced in greater numbers and at a faster rate.
ii) The generated antibody has a higher affinity for the antigen.
6. Which of the following is an invagination of the muscle cell’s sarcolemma?
a) T tubules
b) Sarcoplasmic reticula
c) Microtubules
d) Cisternae
View Answer
Explanation: The invaginations of the sarcolemma of muscle cells are known as transverse tubules.
The following table contains a complete set of multiple-choice questions and answers on protein secondary and tertiary structures, oxygen-binding proteins, protein folding, immune system, actin, and molecular motors.
4. Biochemistry Multiple Choice Questions on Enzymes, Carbohydrates and Gycobiology
1. When the velocity of enzyme activity is plotted against substrate concentration, which of the following is obtained?
a) Straight line with negative slope
b) Straight line with positive slope
c) Parabola
d) Hyperbolic curve
View Answer
Explanation: The rate of formation of an enzyme-substrate complex determines the rate of a reaction at low substrate concentrations.
2. Which of the following catalyzes the reversible degradation of 2-phosphoglycerate to phosphoenolpyruvate?
a) Trypsin
b) Enolase
c) Chymotrypsin
d) Hexokinase
View Answer
Explanation: Enolase is a catalytic enzyme that catalyzes the reversible conversion of 2-phosphoglycerate to phosphoenolpyruvate.
3. Which of the following enzyme catalyzes a reaction that introduces reduced nitrogen ito cellular metabolism?
a) Bacterial dinitrogenase reductase
b) Phosphatase
c) Bacterial glutamine synthase
d) Bacterial dinitrogenase oxidase
View Answer
Explanation: Glutamate synthase in bacteria is one of the most sophisticated regulating enzymes known. It catalyzes a reaction in which reduced nitrogen is introduced into cellular metabolism.
4. Which of the following is an example of epimers?
a) Mannose & Glucose
b) Glucose & Ribose
c) Galactose & Mannose
d) Glucose & Galactose
View Answer
Explanation: Although glucose and galactose have the same chemical formula, the direction of the –OH group on the C4 molecule differs.
5. In which of the following, glucose residues are linked by β1 &arr; 4 glycosidic bonds?
a) Starch
b) Cellulose
c) Glycogen
d) Amylose
View Answer
Explanation: In contrast to the 1 &arr; 4 links of amylose, starch, and glycogen, the glucose residues in cellulose are linked by 1 &arr; 4 glycosidic bonds.
6. Which of the following are important for white blood cell recognition?
a) Glycoproteins
b) Glycosaminoglycans
c) Glycolipids
d) Proteoglycans
View Answer
Explanation: Especially in mammals glycoproteins are essential for white blood cell recognition.
The following table contains a complete set of multiple-choice questions and answers on enzyme kinetics, enzyme actions examples, monosaccharides, proteoglycans, glycoproteins, polysaccharides and disaccharides.
5. Biochemistry MCQ on Nucleotides and Nucleic Acids
1. Which of the following is true about phosphodiester linkage?
a) 3’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the next nucleotide
b) 3’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide
c) 5’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide
d) 5’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the next nucleotide
View Answer
Explanation: A 5’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide.
2. Arrangement of nucleotides in DNA can be seen using which of the following instruments?
a) Electron microscope
b) Light microscope
c) X-Ray crystallography
d) Ultracentrifuge
View Answer
Explanation: It’s a scientific method for figuring out how atoms in a crystalline solid are arranged in three dimensions.
3. Which of the following involves carrying genetic information from DNA for protein synthesis?
a) sn-RNA
b) r-RNA
c) m-RNA
d) t-RNA
View Answer
Explanation: Messenger RNA carries genetic information from DNA for protein synthesis.
4. Which of the following is true about tm?
a) The higher the content of G ≡ C base pairs, the lower the tm
b) The higher the content of A = T base pairs, the higher the tm
c) It can be termed as renaturation temperature
d) The higher the content of G ≡ C base pairs, the higher the tm
View Answer
Explanation: Higher GC content, the melting temperature will be higher because GC content has 3 hydrogen bond and AT has two hydrogen bonds.
5. Which of the following is true about the Z-DNA helix?
a) It has fewer base pairs per turn than B-DNA
b) It tends to be found at the 3’ end of the genes
c) It has alternating GC sequences
d) It is a permanent conformation of DNA
View Answer
Explanation: It is a temporary confirmation of DNA and it has more base pairs per turn than B-DNA.
The following table contains a complete set of multiple-choice questions and answers on nucleic acid structure and chemistry.
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6. Biochemistry MCQ Multiple Choice Questions on DNA-Based Information Technologies
1. Which of the following involves carrying genetic information from DNA for protein synthesis?
a) r-RNA
b) m-RNA
c) sn-RNA
d) t-RNA
View Answer
Explanation: Messenger RNA carries genetic information from DNA for protein synthesis.
2. Which of the following temperature best suits the growth and multiplication of transformed cells?
a) 25°C
b) 26°C
c) 37°C
d) 30°C
View Answer
Explanation: (37-43) °C is the temperature range preferred for the growth and multiplication of transformed cells.
3. Which of the following enzyme is used in PCR?
a) EcoRII
b) EcoRI
c) Taq DNA polymerase
d) HRP
View Answer
Explanation: HRP is an enzyme that is used in ELISA tests. Restriction enzymes are EcorI and EcorII. It is thermostable DNA polymerase obtained from Thermus aquaticus and this enzyme is widely used in PCR for amplification.
4. Recombinant DNA construction involves ____________
a) Cleaving DNA with a restriction endonuclease and joining with polymerase
b) Cleaving and joining DNA with restriction endonuclease
c) Cleaving DNA with a restriction endonuclease and joining with ligase
d) Cleaving DNA with ligase and joining with endonuclease
View Answer
Explanation: Restriction enzymes are called molecular scissors where it cuts the DNA at specific site and the gap is then joined using DNA Ligase enzyme where the 3’-OH of one nucleotide joins to 5’-P of another nucleotide.
5. Which of the following is termed as conserved gene order?
a) Microarray
b) Ortholog
c) Synteny
d) Paralog
View Answer
Explanation: Orthologs are genes from various species that have a clear sequence and functional link.
Paralogs are genes from the same species that are connected in some way.
DNA microarrays are collections of tiny DNA patches glued to a solid surface.
6. Meristem culture helps in developing which of the following?
a) Hybrid plants
b) Virus free plants
c) Tall plants
d) Disease resistant plants
View Answer
Explanation: The infected plant’s apical meristem is collected and cultured in the proper medium to produce fresh, complete, and virus-free plants.
The following table contains a complete set of multiple-choice questions and answers on DNA cloning, genes to genomes, from genomes to proteasomes, and genome alterations.
7. Biochemistry MCQ on Lipids, Biological Membranes and Transport
1. The number of milligrams of KOH required to neutralize the free and combined fatty acid in one gram of a given fat is called __________
a) Polenske number
b) Acid number
c) Saponification number
d) Iodine number
View Answer
Explanation: The saponification number is the number of milligrammes of KOH necessary to neutralise the free and mixed fatty acids in one gramme of a specific fat.
2. Which of the following membrane lipids have a direct glycosidic linkage between the head-group sugar and the backbone glycerol?
a) Ether lipids
b) Sphingolipids
c) Glycolipids
d) Phospholipids
View Answer
Explanation: The head-group sugar and the backbone glycerol have a direct glycosidic connection in glycolipids.
3. Which of the following hormone is responsible for the activation of phospholipase C?
a) Adrenaline
b) Serotonin
c) Cortisol
d) Vasopressin
View Answer
Explanation: Vasopressin activates a particular phospholipase C when it interacts to plasma membrane receptors on the epithelial cells of the renal collecting duct.
4. Which of the following membranes contain low cholesterol and high cardiolipin?
a) Cell wall
b) Inner mitochondrial membrane of the hepatocyte
c) Myelin sheath
d) Plasma membrane
View Answer
Explanation: Low cholesterol and high cardiolipin are seen in the inner mitochondrial membrane.
Cardiolipin levels are low and cholesterol levels are high in the plasma membrane.
5. Which of the following is a choline-containing lipid?
a) Phosphatidylethanolamine
b) Phosphatidylserine
c) Sphingomyelin
d) Phosphatidylglycerol
View Answer
Explanation: Choline-containing lipids in the outer leaflet include phosphatidylcholine and sphingomyelin.
6. Which of the following proteins does not function in cell-cell interaction?
a) Cadherin
b) Cytochrome c
c) Integrin
d) N-CAM
View Answer
Explanation: Integral proteins Integrin, Cadherin, N-CAM and selectin function in cell-cell interaction.
The following table contains a complete set of multiple-choice questions and answers on storage and structural lipids, signals lipids, membranes architecture, membrane dynamics, and solute transport.
8. Biochemistry Multiple Choice Questions on Biosignalling
1. How many types of signal transducers are there?
a) 6
b) 7
c) 8
d) 4
View Answer
Explanation: The six types of signal transducers are gated ion channels, receptor enzymes, membrane proteins that function through G protein, nuclear proteins, membrane proteins, and adhesion receptors.
2. Which of the following is a intracellular second messengers?
a) Glycine
b) Glutamate
c) Acetylcholine
d) IP3
View Answer
Explanation: Inositol triphosphate, in combination with diacylgycerol, is a secondary messenger in cell signalling and lipid signalling.
3. Which of the following is not correct about phosphorylation by IRS on serine residue?
a) Target tissues fail to respond to circulating insulin
b) It increases insulin levels
c) It is an inhibitory phosphorylation
d) It is molecular mechanism for insulin resistance
View Answer
Explanation: Insulin resistance is a disease in which target tissues fail to respond to circulating insulin. Inhibitory serine phosphorylation is a biological mechanism underlying insulin resistance.
4. Which of the following catalyzes the cutting of PIP2 into 2 moles of IP3 and diacylglycerol in cell signaling?
a) Phosphodiesterase C
b) Phosphokinase C
c) Phospholipase C
d) Lipokinase
View Answer
Explanation: PLC, or phospholipase, binds to PIP2 and breaks it down into diacylglycerol and IP3.
5. Which of the following directly phosphorylate tyrosines to start a kinase protein enzymatic cascade?
a) Receptor threonine kinase
b) Receptor serine kinase
c) Receptor tyrosine kinase
d) Receptor guanylyl cyclases
View Answer
Explanation: To initiate a kinase protein enzymatic cascade, only receptor tyrosine kinase directly phosphorylates tyrosine.
6. The 2-component system drives bacterial chemotaxis by coupling autophosphoryaltion of which receptor to phosphorylation of respective regulatory protein?
a) Guanylyl cyclase
b) His kinase
c) Adenylyl cyclase
d) All of the mentioned
View Answer
Explanation: By connecting auto-phosphorylation of his kinase to phosphorylation of the relevant regulatory protein, the two-component system causes bacterial chemotaxis.
7. When visual stimulus reaches receptors in retina of eye, first process involving absorption of physical energy by receptors is?
a) Coding
b) Adaptation
c) Transduction
d) Reception
View Answer
Explanation: When a visual signal reaches receptors in the retina of the eye, the initial phase involved in the absorption of physical energy by receptors is called reception.
8. Which of the following drug is used to terminate early pregnancies?
a) Victoza
b) Glucophage
c) RU486
d) Metformin
View Answer
Explanation: Metformin, Glucophage and victoza are the drugs to cure diabetes.
9. Which of the following occurs in meiosis but not in mitosis?
a) Pairing of homologous chromosomes at metaphase plate
b) Separation of sister chromatids at anaphase
c) Attachment of spindle fibers to kinetochore
d) Replication of DNA prior to start of cell division
View Answer
Explanation: Pairing of homologous chromosomes at metaphase plate does not occur in mitosis.
10. Migration of cancerous cells from the site of origin to other part of the body forming secondary tumors is called ___________
a) Proliferation
b) Diapedesis
c) Apoptosis
d) Metastasis
View Answer
Explanation: Metastasis is the spread of malignant cells from their original site to other parts of the body, resulting in additional tumours.
The following table contains a complete set of multiple-choice questions and answers on signal and sensory transduction, gated ion channels, receptor enzymes, g-proteins, multivalent scaffold proteins, plants signalling, oncogenes, transcription and cell cycle regulation.
9. Biochemistry MCQ on Principles of Bioenergetics and Glycolysis
1. Which of the following is the study of energy relationships and conversions in biological systems?
a) Biochemistry
b) Biophysics
c) Biotechnology
d) Bioenergetics
View Answer
Explanation: Bioenergetics is the study of energy relationships and conversions in biological systems.
2. Anabolism and catabolism are chemically linked in the form of __________
a) ASP
b) ADP
c) ATP
d) Phosphodiester linkage
View Answer
Explanation: Anabolism is an energy-intake process in which tiny molecules grow into larger molecules, whereas catabolism is an energy-output process in which large molecules break down into smaller molecules.
3. Which of the following is not a flavoprotein?
a) NADH dehydrogenase-Qreductase
b) Succinate dehydrogenase
c) Xanthine oxidase
d) Cytochrome c
View Answer
Explanation: The flavoprotein cytochrome c is not a flavoprotein. Flavoproteins participate in oxidation reactions in which electrons are lost but cytochrome c receives them.
4. Whenever the cell’s ATP supply is depleted, which of the following enzyme’s activity is increased?
a) Pyruvate kinase
b) Phosphofructokinase-1
c) Hexokinase
d) Glucokinase
View Answer
Explanation: Phosphofructokinase-1 is a regulatory enzyme that plays a key role in glycolysis control. When the cell’s ATP supply is reduced, its activity increases.
5. Which of the following enzyme is responsible for the conversion of glucose 1-phosphate to glucose 6-phosphate?
a) Epimerase
b) Phosphoglucomutase
c) Glycogen phosphorylase
d) Isomerase
View Answer
Explanation: Phosphoglucomutase is an enzyme that transforms glucose 1-phosphate to glucose 6-phosphate, which can then be used in glycolysis.
6. Which is the major factor(s) determining whether glucose is oxidized by aerobic or anaerobic glycolysis?
a) Presence of high AMP
b) NADH and the ATP/ADP ratio
c) Ca+2
d) FADH2
View Answer
Explanation: The key determinants of whether glucose is metabolised by aerobic or anaerobic glycolysis are NADH and the ATP/ADP ratio.
7. Which of the following is not an important precursor of glucose in animals?
a) Pyruvate
b) Glucose 6-phosphate
c) Lactate
d) Glycerol
View Answer
Explanation: Three-carbon molecules including lactate, pyruvate, and glycerol, as well as some amino acids, are significant precursors of glucose in animals.
8. Which of the following enzymes acts in the pentose phosphate pathway?
a) 6-phosphogluconate dehydrogenase
b) Pyruvate kinase
c) Glycogen phosphorylase
d) Aldolase
View Answer
Explanation: 6-phosphogluconate dehydrogenase catalyses the first step in the pentose phosphate pathway.
The following table contains a complete set of multiple-choice questions and answers on bioenergetics and thermodynamics, phosphoryl group transfers, biological oxidation, glycolysis, feeder pathways, fermentation and gluconeogenesis.
10. Biochemistry MCQ on Principles of Metabolic Regulation: Glucose and Glycogen
1. Which of the following is not a factor determining the activity of an enzyme?
a) Nucleotides
b) Association with regulatory protein
c) Sequestration
d) Allosteric regulation
View Answer
Explanation: The factors that determine an enzyme’s activity are its association with regulatory proteins, sequestration, allosteric regulation, and covalent modification.
2. How many steps are catalyzed by different enzymes in glycolysis and gluconeogenesis?
a) 3
b) 4
c) 1
d) 2
View Answer
Explanation: In glycolysis, hexokinase, phosphofructokinase-1, and pyruvate kinase, and in gluconeogenesis, glucose 6-phosphatase, fructose 1, 6-bisphosphatase, PEP carboxykinase, and pyruvate carboxylase.
3. Which compounds are responsible for the coordinated regulation of glucose and glycogen metabolism?
a) Fructose 2, 6-bisphosphate
b) Acetyl co-A
c) NADH
d) NAD+
View Answer
Explanation: Fructose 2, 6-bisphosphate is a hormone that regulates glycolysis and gluconeogenesis.
4. Which of the following is a measure of the effect of an enzyme’s concentration on flux through a multi-enzyme pathway?
a) Metabolic control
b) Response coefficient
c) Elasticity coefficient
d) Flux control coefficient
View Answer
Explanation: The elasticity coefficient is a measurement of how responsive an enzyme is to variations in metabolite concentration.
The response coefficient is an expression for the empirically determined change in flow across a pathway in response to a regulatory hormone or second messenger.
5. Which of the following is a measure of how responsive the enzyme is to changes in the concentration of a metabolite?
a) Metabolic control
b) Response coefficient
c) Flux control coefficient
d) Elasticity coefficient
View Answer
Explanation: The flux control coefficient is a measurement of how the concentration of one enzyme affects flux across a multi-enzyme pathway.
The response coefficient is an expression for the empirically determined change in flow across a pathway in response to a regulatory hormone or second messenger.
The following table contains a complete set of multiple-choice questions and answers on metabolic pathways, glycolysis regulation, glycogen synthesis and breakdown, metabolic control analysis.
11. Biochemistry MCQ on Amino Acid Oxidation and the Production of Urea
1. Which is the first step in the catabolism of most L-amino acids once they have reached the liver is promoted?
a) Glutamine synthase
b) Glutamate dehydrogenase
c) Glutaminase
d) Amino transferases
View Answer
Explanation: The removal of the -amino groups by enzymes called amino transferases or trasaminases is the first step in the catabolism of most L-amino acids once they reach the liver.
2. Which of the following operates at an important intersection of carbon and nitrogen metabolism?
a) Glutamine synthase
b) Glutamate dehydrogenase
c) Glutaminase
d) Amino transferases
View Answer
Explanation: Glutamate dehydrogenase is found at the crossroads of carbon and nitrogen metabolism.
3. Which of the following is the first amino group entering into urea cycle?
a) Argininosuccinate
b) Cituilline
c) Carbamoyl phosphate
d) Ornithine
View Answer
Explanation: The urea cycle is entered by carbamoyl phosphate, which acts as an active carbamoyl group donor.
4. Which of the following are exclusively glucogenic?
a) Lysine
b) Leucine
c) Threonine
d) Arginine
View Answer
Explanation: Leucine and lysine are exclusively ketogenic. Threonine is both ketogenic and glucogenic.
5. Which of the following produces pyruvate?
a) Alanine
b) Leucine
c) Isoleucine
d) Lysine
View Answer
Explanation: Pyruvate is made up of the amino acids alanine, cysteine, glycine, serine, threonine, and tryptophan.
The following table contains a complete set of multiple-choice questions and answers on metabolic fates of amino groups, nitrogen excretion and amino acid degradation.
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12. Biochemistry Multiple Choice Questions on Oxidative Phosphorylation and Photophosphorylation
1. Complex 4 is also known as _________
a) Cytochrome oxidase
b) NADH dehydrogenase
c) Succinate dehydrogenase
d) Cytochrome bc1 complex
View Answer
Explanation: Complex IV, also known as cytochrome oxidase, catalyzes the final
step in the mitochondrial electron transport chain and is one of the key regulators of oxidative
phosphorylation.
2. Which of the following is the prosthetic group of NADH dehydrogenase?
a) FAD
b) FMN
c) NADH
d) NADPH
View Answer
Explanation: NADH attaches to complex I and transfers two electrons to the enzyme’s flavin mononucleotide (FMN) prosthetic group, resulting in FMNH2.
3. Long-chain fatty acids are oxidized step-wise in one-carbon unit starting from ____________
a) Aliphatic end
b) Carboxyl end
c) a and b
d) None of the mentioned
View Answer
Explanation: Long-chain fatty acids are oxidized step-wise in one-carbon unit starting from carboxyl end.
4. Which effects the increased levels of hydrogen ions in the inter-membrane space of the mitochondria?
a) Decreased levels of chemiosmosis
b) Increased levels of water in inter-membrane space
c) Increase ATP production
d) Decreased levels of oxidative phosphorylation
View Answer
Explanation: When the levels of hydrogen ions in the intermembrane gap of the mitochondria rise, ATP generation rises.
5. How many mitochondrial proteins are encoded in nuclear genes and imported into mitochondria after their synthesis?
a) 300
b) 500
c) 700
d) 900
View Answer
Explanation: About 900 distinct mitochondrial proteins are encoded in nuclear genes and then synthesised in mitochondria.
6. What is the effect of the excessive rate of apoptosis?
a) AIDS
b) Fever
c) Atrophy
d) Sneezing
View Answer
Explanation: Apoptosis in excess causes atrophy, whereas apoptosis insufficiently promotes uncontrolled cell proliferation.
7. Which one of the following is the source of electrons in photosynthesis?
a) NADH
b) Water
c) Carbohydrates
d) CO2
View Answer
Explanation: In photosynthesis, water is the source of electrons. To decrease oxidized chlorophyll molecules, these electrons are necessary.
8. Which of the following is the correct sequence for the movement of electrons during the light-dependent reactions of plants?
a) P680, water, P700, NADP+
b) Water, P680, P700, NADP+
c) P700, P680, NADP+, water
d) Water, P700, NADP+, P680
View Answer
Explanation: The sequence for the movement of electrons firstly includes water, secondly P680 then P700 and finally NADP+.
The following table contains a complete set of multiple-choice questions and answers on electro transfer reactions, atp synthesis, mitochondrial genes, oxidative stress, photophosphorylation features, light driven electron flow and photophosphorylation atp synthesis.
13. Biochemistry MCQ on Lipid Biosynthesis, Biosynthesis of Amino Acids, Nucleotides and Related Molecules
1. Which of the following condenses acyl and malonyl groups?
a) Acetyl co-A ACP transacetylase
b) Malonyl co-A ACP transferase
c) β-ketoacyl ACP synthase
d) Acyl carrier protein
View Answer
Explanation: Malonyl co-A ACP transferase transfers malonyl group from co-A to ACP.
Acyl carrier protein carries acyl groups in thio-ester linkage.
Acetyl co-A ACP transacetylase transfers acyl group from co-A to cys residue of KS.
2. Which of the following class of drugs reduce the levels of fatty acids circulating in the blood?
a) Amphetamines
b) Thiazolidinediones
c) Synthetic cannabinoids
d) Cathinones
View Answer
Explanation: Thiazolidinediones reduce the levels of fatty acids circulating in the blood and increase sensitivity to insulin.
3. Which of the following is involved in the bio-signaling pathway that includes membrane turnover and exocytosis?
a) Phosphatidyl glycerol
b) Phosphatidylinositol
c) Phosphatidyl glycerol and myoinositol
d) Myoinositol
View Answer
Explanation: Phosphatidylinositol is involved in the bio-signaling pathway that includes membrane turnover and exocytosis.
4. How many carbons are present in HMG co-A?
a) 12
b) 8
c) 4
d) 6
View Answer
Explanation: Two molecules of acetyl co-A condense to form acetoacetyl co-A, which condenses with the third molecule of acetyl co-A to yield a six-carbon compound HMG co-A.
5. Which of the following catalyzes reactions that incorporate nitrogen derived from glutamine?
a) Glutamine synthase
b) Glutamine amidotransferase
c) Adenylyltransferase
d) Glutamate synthase
View Answer
Explanation: Glutamine amidotransferase catalyzes reactions that incorporate nitrogen derived from glutamine.
6. Which of the following gives rise to methionine, threonine, and lysine?
a) Glutamate
b) Serine
c) Pyruvate
d) Aspartate
View Answer
Explanation: Aspartate gives rise to methionine, threonine, and lysine. Branch points occur at aspartate semialdehyde, an intermediate in all three pathways, and at homoserine, a precursor of threonine and methionine.
7. Which of the following gives rise to γ-amino butyrate?
a) Pyruvate decarboxylation
b) Glutamine synthase
c) Glutamate synthase
d) Glutamate decarboxylation
View Answer
Explanation: Glutamate decarboxylation gives rise to γ-amino butyrate.
8. Which of the following is degraded to methylmalonyl semialdehyde?
a) Leucine
b) Thymine
c) Glutamine
d) Tyrosine
View Answer
Explanation: Thymine is degraded to methylmalonyl semialdehyde.
The following table contains a complete set of multiple-choice questions and answers on biosynthesis of fatty acids, triacylglycerols, membrane phospholipids, cholestrol and amino acids, nitrogen metabolism, molecules and degradation of nucleotides.
14. Biochemistry Multiple Choice Questions on Genes and Chromosomes
1. Which of the following has the lowest level of chromosome organization?
a) 30nm fiber
b) Nucleosome
c) Solenoid
d) None of these
View Answer
Explanation: It is the fundamental component of a chromosomal package, consisting of a DNA segment wrapped around a histone core.
2. Which type of supercoiling takes the form of extended right-handed coils?
a) Positive supercoiling
b) Negative supercoiling
c) Plectonemic supercoiling
d) Solenoidal supercoiling
View Answer
Explanation: Solenoidal (negative) supercoiling is represented by tight left-handed twists around an imaginary tube-like structure, while plectonemic supercoiling is represented by right-handed coils.
3. Which of the following plays a substantial role in linking together sister chromatids immediately after replication?
a) Topoisomerases
b) Histones
c) Condensins
d) Cohesins
View Answer
Explanation: Cohesins are important for binding sister chromatids together after replication and keeping them together as the chromosomes condense to metaphase.
4. Which of the following has beads on a string structure?
a) Nucleosomes
b) Chromosomes
c) Heterochromatin
d) Chromatin
View Answer
Explanation: Nucleosomes are formed when DNA wraps around histone proteins, like beads on a thread.
5. Which of the following histones shows more sequence similarity among eukaryotic species?
a) H2A
b) H3
c) H1
d) H2B
View Answer
Explanation: In all eukaryotes, the amino acid sequences of H3 and H4 histones are substantially identical.
The following table contains a complete set of multiple-choice questions and answers on chromosomal elements, dna supercoiling and chromosomes structure.
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15. Biochemistry MCQ on DNA, RNA and Protein Metabolism
1. Which of the following enzymes remove supercoiling in replicating DNA ahead of the replication fork?
a) Topoisomerases
b) Primases
c) Helicases
d) DNA polymerases
View Answer
Explanation: Strand separation causes topological stress in the helical DNA structure, which topoisomerases can alleviate.
2. Which of the following mechanisms will remove uracil and incorporate the correct base?
a) Nucleotide excision repair
b) Direct repair
c) Base excision repair
d) Mismatch repair
View Answer
Explanation: Small, non-helix-distorting base lesions are removed from the genome through base excision repair.
3. Which of the following process occurs in regions where no large–scale sequence similarity is apparent?
a) Site specific recombination
b) Replicative recombination
c) Homologous genetic recombination
d) Non-homologous recombination
View Answer
Explanation: Recombination between certain short sequences on otherwise distinct parental molecules is known as site-specific recombination.
Replicative recombination creates a new transposable element copy at a different place on the DNA strand.
Homologous genetic recombination occurs when DNA molecules with similar sequences come together.
4. TBP stands for?
a) Transcription factor binding protein
b) Transcription associated factor
c) TATA box polymerase
d) TATA-box binding protein
View Answer
Explanation: TBP stands for TATA-box binding protein.
5. Which of the following is not involved in the post-transcriptional processing of t-RNA?
a) Attachment of poly-A tail
b) Base modulation
c) Attachment of CCA arm
d) Splicing
View Answer
Explanation: There is no poly A tail in mature tRNA. Poly A tail is the common change occurring in the eukaryotic mRNA.
6. Which of the following is an example of RNA-dependent DNA polymerase?
a) RNA polymerase II
b) DNA ligase
c) Reverse transcriptase
d) RNA polymerase I
View Answer
Explanation: Reverse transcriptase (RT), also known as RNA-dependent DNA polymerase, is a DNA polymerase enzyme that transcribes single-stranded RNA into DNA. This enzyme is able to synthesize a double helix DNA once the RNA has been reverse transcribed in a first step into a single-strand DNA.
7. Which position of a codon is said to wobble?
a) Fourth
b) First
c) Second
d) Third
View Answer
Explanation: 3rd position is said to wobble in codon. Binding of a codon in an mRNA the cognate tRNA is much “looser” in the third position of the codon. This permits several types of non-Watson–Crick base pairing to occur at the third codon position.
8. Which of the following inactivates the 60S subunit of eukaryotic ribosomes?
a) Ricin
b) Chloramphenicol
c) Cycloheximide
d) Diphtheria toxin
View Answer
Explanation: By depurination of particular adenosine in 23S rRNA, ricin inactivates the 60S component of eukaryotic ribosomes.
9. How many amino acid residues are there in ubiquitin?
a) 70
b) 72
c) 74
d) 76
View Answer
Explanation: One of the most highly conserved proteins is known as ubiquitin (76 amino acid residues).
The following table contains a complete set of multiple-choice questions and answers on dna replication and repair, dna recombination and synthesis of rna, rna processing, genetic code, protein synthesis, targeting and degradation.
16. Biochemistry Multiple Choice Questions on Regulation of Gene Expression and Miscellaneous
1. Which of the following are the structural motifs that mediate protein-protein interactions?
a) Zinc finger
b) Helix-turn-helix
c) Homeodomain
d) Leucine zipper and basic helix-loop-helix
View Answer
Explanation: Leucine zipper will mediate protein interaction facilitates the dimerization of the protein by interdigitation of two leucine-containing helices on different molecules.
2. Which of the following bacterial operon is not controlled by attenuation?
a) Histidine
b) Leucine
c) Arabinose
d) Tryptophan
View Answer
Explanation: Arabinose is a carbohydrate.
3. Which of the following regulatory sequence allows transcription to continue?
a) Sequence 4
b) Sequence 1
c) Sequence 2
d) Sequence 3
View Answer
Explanation: A tryptophan-sensitive mechanism requires regulatory sequence 1.
Sequence 2 is a complementary sequence to sequence 3.
Attenuating transcription is the purpose of Sequence 4.
4. Which of the following enzyme is secreted by the pancreas?
a) Myoglobin
b) Cytochrome c
c) Ribonuclease
d) Lysozyme
View Answer
Explanation: The pancreas secretes ribonuclease into the small intestine, where it catalyses the hydrolysis of specific bonds in ingested ribonucleic acids.
5. Which of the following is a hypertonic solution?
a) 0.45% sodium chloride
b) Oceans
c) Red blood cells placed in fresh water
d) Freshwater habitats
View Answer
Explanation: Many marine animals’ extracellular fluid is hypertonic to sea water/oceans. By regularly evacuating salt water, these marine species escape the challenge of hyper tonicity.
6. Which of the following catalyzes the cutting of PIP2 into 2 moles of IP3 and diacylglycerol in cell signaling?
a) Lipokinase
b) Phosphokinase C
c) Phosphodiesterase C
d) Phospholipase C
View Answer
Explanation: PLC also named phospholipase grabs onto PIP2 and cuts it into diacylglycerol and IP3.
The following table contains a complete set of multiple-choice questions and answers on gene regulation principles, gene expression in prokaryotes, and miscellaneous.
Wish you the best in your endeavor to learn and master Biochemistry!