Category: Biochemistry Objective Questions

Biochemistry Questions and Answers for Campus interviews focuses on “Mitochondrial Genes: Their Origin and the Effects of Mutations”.

1. How many human mitochondrial proteins are encoded in the mitochondrial genome and synthesized within mitochondria?
A. 11
B. 12
C. 13
D. 14
Answer: C
Clarification: 13 human mitochondrial proteins are encoded in the mitochondrial genome and synthesized within mitochondria.

2. How many mitochondrial proteins are encoded in nuclear genes and imported into mitochondria after their synthesis?
A. 600
B. 700
C. 800
D. 900
Answer: D
Clarification: About 900 different mitochondrial proteins are encoded in nuclear genes and imported into mitochondria after their synthesis.

3. What is Mitochondrial DNA?
A. Simple, single stranded linear DNA molecule
B. Simple, single stranded circular DNA molecule
C. Simple, double stranded linear DNA molecule
D. Simple, double stranded circular DNA molecule
Answer: D
Clarification: Mitochondrial DNA (mt DNA. is a simple, double stranded circular DNA molecule.

4. Oxysomes or F₀ – F₁ particles occur on _____________
A. Inner mitochondrial membrane
B. Chloroplast surface
C. Mitochondrial surface
D. Thylakoids
Answer: A
Clarification: Oxysomes which are also called as F₀ – F₁ particles are present on the surface of the folded inner mitochondrial membrane.

5. More than what proportion of mitochondrial proteins are coded by nuclear DNA?
A. 95%
B. 50%
C. 10%
D. 40%
Answer: A
Clarification: More than 95% of mitochondrial proteins are coded by nuclear DNA.

6. What is the size of human mitochondrial DNA?
A. 16kb
B. 200kb
C. 2500kb
D. 100kb
Answer: A
Clarification: The size of human mitochondrial DNA is 16kb.

7. What is the size of plant mitochondrial DNA?
A. 16kb
B. 200-2500kb
C. 100- 2550kb
D. 100-2500kb
Answer: B
Clarification: The size of plant mitochondrial DNA is in the range of 200-2500kb.

8. Typically how many copies of DNA is/are there in each mitochondrion?
A. 1
B. 11
C. 10
D. 12
Answer: C
Clarification: Typically 2-10 copies of DNA are there in each mitochondrion.

9. Mitochondrial DNA is one of the best marker tools for population biologists and evolutionary biologists because _____________
A. Absence of genetic recombination in mt-DNA
B. Mitochondrial genes are specific to mt-DNA
C. It can be easily isolated
D. It undergoes spontaneous mutation
Answer: A
Clarification: Mitochondrial DNA is one of the best marker tools for population biologists and evolutionary biologists because of the absence of genetic recombination in mt-DNA.

10. The mechanism of action of cyanide, a mitochondrial toxin, is by inhibiting ____________
A. ATP synthase
B. Succinate dehydrogenase
C. Cytochrome c oxidase
D. NADH dehydrogenase
Answer: C
Clarification: Cyanide inhibits cytochrome c oxidase.

of Biochemistry for Campus Interviews, .

Biochemistry Multiple Choice Questions on “Glycolysis”.

1. Which of the following enzyme catalyzes the first step of glycolysis?
A. Hexokinase
B. Pyruvate kinase
C. Glucokinase
D. Phosphofructokinase-1
Answer: A
Clarification: The first of glycolysis is irreversible under intracellular conditions and is catalyzed by hexokinase.

2. What is the general term used for the anaerobic degradation of glucose to obtain energy?
A. Anabolism
B. Oxidation
C. Fermentation
D. Metabolism
Answer: C
Clarification: Fermentation is the general term used for the degradation of glucose to obtain energy in the form of ATP.

3. Whenever the cell’s ATP supply is depleted, which of the following enzyme’s activity is increased?
A. Hexokinase
B. Pyruvate kinase
C. Glucokinase
D. Phosphofructokinase-1
Answer: D
Clarification: Phosphofructokinase-1 is a regulatory enzyme; it is the major point of regulation in glycolysis. Its activity is increased whenever the cell’s ATP supply is depleted.

4. Cleavage of Fructose 1, 6-biophosphate yields ___________
A. Two aldoses
B. Two ketoses
C. An aldose and a ketose
D. Only a ketose
Answer: C
Clarification: Fructose 1, 6-biophosphate is cleaved to yield glyceraldehyde 3-phosphate, an aldehyde and dihydroxyacetone phosphate, a ketose.

5. Dihydroxyacetone phosphate is rapidly and reversibly converted to ___________
A. Glyceraldehyde 3-phosphate
B. 1, 3-bis-phosphoglycerate
C. Fructose 1, 6-bisphosphate
D. Fructose 6-phosphate
Answer: A
Clarification: Dihydroxyacetone phosphate is rapidly and reversibly converted to glyceraldehyde 3-phosphate by triose phosphate isomerase.

6. What is the first step in the payoff phase of glycolysis?
A. Reduction of 1, 3-bisphosphoglycerate to glyceraldehyde 3-phosphate
B. Oxidation of glyceraldehyde 3-phosphate to 1, 3-bisphosphoglycerate
C. Reversible conversion of dihydroxyacetone phosphate to glyceraldehyde 3-phosphate
D. Irreversible conversion of dihydroxyacetone phosphate to glyceraldehyde 3-phosphate
Answer: B
Clarification: Glyceraldehyde 3-phosphate dehydrogenase catalyzes the first step in the payoff phase, oxidation of glyceraldehyde 3-phosphate to 1, 3-bisphosphoglycerate.

7. Which substrate is used in the last step of glycolysis?
A. Glyceraldehyde 3-phosphate
B. Pyruvate
C. Phosphoenolpyruvate
D. 1, 3-bisphosphoglycerate
Answer: C
Clarification: The last step in glycolysis is the transfer of phosphoryl group from phosphoenolpyruvate to ADP catalyzed by pyruvate kinase.

8. High concentration of glucose 6-phosphate is inhibitory to ___________
A. Hexokinase
B. Pyruvate kinase
C. Glucokinase
D. Phosphofructokinase-1
Answer: A
Clarification: Hexokinase catalyzes the reaction involving conversion of glucose to glucose 6-phosphate.

9. The product formed in the first substrate level phosphorylation in glycolysis is ___________
A. Pyruvate
B. 3-phosphoglycerate
C. 1, 3-bisphosphoglycerate
D. 2-phosphoglycerate
Answer: B
Clarification: Phosphoglycerate kinase transfers phosphoryl group from 1, 3-bisphosphoglycerate to ADP forming ATP and 3-phosphoglycerate.

10. Glycolysis converts ___________
A. Glucose into pyruvate
B. Glucose into phosphoenolpyruvate
C. Fructose into pyruvate
D. Fructose into phosphoenolpyruvate
Answer: A
Clarification: Glycolysis is a metabolic pathway that converts glucose into pyruvate.

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Basic Biochemistry Questions and Answers focuses on “The Composition and Architecture of Membranes”.

1. Which of the following acts as a passive electrical insulator?
A. Myelin sheath
B. Plasma membrane
C. Inner mitochondrial membrane
D. Outer mitochondrial membrane
Answer: A
Clarification: Myelin sheath acts as a passive electrical insulator.

2. Which of the following membranes contain low cholesterol and high cardiolipin?
A. Myelin sheath
B. Plasma membrane
C. Inner mitochondrial membrane of hepatocyte
D. Cell wall
Answer: C
Clarification: Inner mitochondrial membrane contains low cholesterol and high cardiolipin.
Plasma membrane has high cholesterol and low cardiolipin.

3. Which of the following is important in signal transduction triggered by hormones?
A. Phosphatidylinositol and its derivatives
B. Phosphatidylserine and its derivatives
C. Phosphatidylglycerol and its derivatives
D. Phosphatidylethanolamine
Answer: A
Clarification: Phosphatidylinositol and its derivatives are important in signal transduction triggered by hormones.

4. Which of the following are the major component of chloroplast membrane of plants and are absent from animal cells?
A. Glycolipids
B. Phospholipids
C. Ether lipids
D. Triacylglycerols
Answer: A
Clarification: Glycolipids are the major component of chloroplast membrane of plants and are absent from animal cells.

5. How many types of lipid aggregates are formed when amphipathic lipids are mixed with water?
A. 1
B. 2
C. 3
D. 4
Answer: C
Clarification: Micelle, bilayer and liposome are the 3 types of lipid aggregates are formed when amphipathic lipids are mixed with water.

6. Which of the following types of lipid aggregates has maximum stability?
A. Micelles
B. Bilayer
C. Liposome
D. Myelin sheath
Answer: C
Clarification: Bilayer is relatively unstable and spontaneously forms a third type of aggregate, folds back on itself to form a hollow sphere, liposome that has maximum stability in their aqueous environment.

7. When cross sectional area of the head group and acyl side chain is similar, which of the following lipid aggregates formation is favored?
A. Micelles
B. Bilayer
C. Liposome
D. Myelin sheath
Answer: B
Clarification: Bilayer formation is favored when cross sectional area of the head group and acyl side chain is similar.

8. When cross sectional area of the head group is greater than that of the acyl side chain, which of the following lipid aggregates formation is favored?
A. Micelles
B. Bilayer
C. Liposome
D. Myelin sheath
Answer: A
Clarification: Micelles formation is favored when cross sectional area of the head group is greater than that of the acyl side chain.

9. Which of the following is choline containing lipid?
A. Sphingomyelin
B. Phosphatidylserine
C. Phosphatidylglycerol
D. Phosphatidylethanolamine
Answer: A
Clarification: Phosphatidylcholine and sphingomyelin present in the outer leaflet are the choline containing lipids.

10. A platelet is able to play its role in the formation of blood clot when one of the glycerophospholipids in the plasma membrane moves into the outer leaflet.
A. Phosphatidylserine
B. Phosphatidylethanolamine
C. Phosphatidylinositol
D. Phosphatidylglycerol
Answer: A
Clarification: Only when phosphatidylserine in the plasma membrane moves into the outer leaflet is a platelet able to play its role in the formation of blood clot.

11. Which of the following glycerophospholipids is not common in inner leaflet (cytoplasmic)?
A. Phosphatidylserine
B. Phosphatidylethanolamine
C. Phosphatidylinositol
D. Phosphatidylcholine
Answer: D
Clarification: Phosphatidylcholine is common in outer leaflet.

12. Which of the following has high lipid content?
A. Myelin sheath
B. Plasma membrane
C. Inner mitochondrial membrane
D. Outer mitochondrial membrane
Answer: A
Clarification: Myelin sheath relatively contains high lipid content.

13. Plasma membrane is permeable to __________
A. ATP
B. Glucose
C. K⁺
D. Urea
Answer: D
Clarification: Plasma membrane is impermeable to ATP, glucose and K⁺.

14. How are the intrinsic proteins in cell membrane distributed?
A. Uniform
B. Random
C. Symmetric
D. Asymmetric
Answer: D
Clarification: Intrinsic proteins in cell membrane are distributed symmetrically.

To practice basic questions and answers on all areas

Biochemistry Multiple Choice Questions on “Monosaccharides and Disaccharides”.

1. Anthrone method is preferred in the determination of ___________
A. Carbohydrates
B. Proteins
C. Vitamins
D. Fats
Answer: A
Clarification: Carbohydrates are dehydrated with con.H₂SO₄ to form Furfural, which condenses with anthrone to form a green color.

2. Which of the following is an example of epimers?
A. Glucose & Galactose
B. Glucose & Ribose
C. Mannose & Glucose
D. Galactose & Mannose
Answer: A
Clarification: Both glucose and galactose have the same chemical formula but the orientation of –OH group on C4 molecule in both the compounds are different.

3. Which of the following has reducing properties?
A. Glucuronic acid
B. Gluconic acid
C. Glucaric acid
D. Mucic acid
Answer: A
Clarification: Glucuronic acid has a free aldehyde group which is responsible for reducing property.

4. The red precipitate formed when glucose is heated with “Benedict’s reagent” is ___________
A. Cupric hydroxide
B. Cuprous hydroxide
C. Cupric oxide
D. Cuprous oxide
Answer: D
Clarification: When reducing sugars are heated in the presence of an alkali and reduce the Cupric compounds present in the Benedict’s reagent to cuprous compounds which get precipitated as insoluble red Cu₂O.

5. Fructose and Glucose can be distinguished by ___________
A. Selwinoff’s reagent
B. Benedict’s reagent
C. Fehling’s reagent
D. Barfoed’s reagent
Answer: A
Clarification: Selwinoff’s reagent gives positive test for fructose.

6. Which of the following is an example of monosaccharide?
A. Galactose
B. Sucrose
C. Lactose
D. Maltose
Answer: A
Clarification: Galactose is a simple sugar that consists of a single polyhydroxy aldehyde.

7. Which of the following is an example of disaccharide?
A. Glucose
B. Fructose
C. Galactose
D. Maltose
Answer: D
Clarification: Maltose is a disaccharide with two monosaccharide glucose units.

8. In maltose, between which of the following carbons there is a linkage?
A. C1, C2
B. C2, C3
C. C1, C4
D. C2, C4
Answer: C
Clarification: Maltose contains two D-glucose residues joined by a glycosidic linkage between C1 of one glucose residue and C4 of the other.

9. Which of the following carbohydrates is a triose?
A. Glucose
B. Ribose
C. Ribulose
D. Glyceraldehyde
Answer: D
Clarification: Glyceraldehyde is a triose containing 3 carbons.

10. Lactose is a disaccharide of which of the following sugar units?
A. Glucose and fructose
B. Glucose and galactose
C. Glucose and sucrose
D. Glucose and ribose
Answer: B
Clarification: Lactose is a disaccharide of glucose and galactose.

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Biochemistry Questions and Answers for Freshers focuses on “Buffering against pH changes in Biological Systems”.

1. Which can act as buffer?
A. NH₄ Cl + HCl
B. CH₃ COOH + H₂ CO₃
C. 40ml of 0.1M NaCN + 20ml of 0.1M HCN
D. NaCl + NaOH
Answer: C
Clarification: It is a mixture of weak acid and its salt with strong base.

2. Calculate the pH of a mixture of 0.10M acetic acid and 0.20M sodium acetate. The pK_a of acetic acid is 4.76.
A. 5.1
B. 4.1
C. 6.1
D. 7.1
Answer: A
Clarification: pH = pK_a + log [acetate]/[acetic acid]
= 4.76 + log (0.2/0.1)
= 4.76 + 0.30
= 5.1.

3. Calculate the pK_a of lactic acid, given that when the concentration of lactic acid is 0.010M and the concentration of lactate is 0.087M, the pH is 4.80.
A. 4.0
B. 3.9
C. 3.3
D. 4.1
Answer: B
Clarification: pH = pK_a + log [lactate]/[lactic acid]
pK_a = pH – log [lactate]/[lactic acid]
= 4.80 – log (0.087/0.010) = 4.80 – log 8.7
= 3.9.

4. Calculate the ratio of the concentrations of acetate and acetic acid required in a buffer system of pH 5.30.
A. 3.2
B. 3.3
C. 3.4
D. 3.5
Answer: D
Clarification: pH = pK_a + log [acetate]/[acetic acid]
log [acetate]/[acetic acid] = pH – pK_a
= 5.30 – 4.76 = 0.54
[acetate]/[acetic acid] = antilog 0.54 = 3.5.

5. Assertion A: pH of a buffer solution solution does not change on dilution.
Reason R: On dilution the ration of concentration of salt and acid (or base) remains unchanged.
A. A and R are true, R is the correct explanation of A
B. A and R are true, R is not correct explanation of A
C. A is true but R is false
D. A is false but R is true
Answer: A
Clarification: On dilution pH of buffer solution remains unchanged because the ratio of concentration of salt and acid (or base) remains unchanged.

6. Which of the following mixture in aqueous solution of equimolar concentration acts as a buffer solution?
A. HNO₃ + NaOH
B. H₂ SO₄ + KOH
C. NH₄ OH(excess) + HCl
D. CH₃ COOH + NaOH(excess)
Answer: C
Clarification: NH₄ OH(excess) + HCl → NH₄ Cl + H₂O
So the mixture contains NH₄ OH + NH₄ Cl.

7. 1M NaCl and 1M HCl are present in an aqueous solution. The solution is ____________
A. Not a buffer solution with pH < 7
B. Not a buffer solution with pH > 7
C. A buffer solution with pH < 7
D. A buffer solution with pH > 7
Answer: A
Clarification: It is a neutral solution and its pH = 7.

8. For an acid buffer solution the pH is 3. The pH can be increased by ____________
A. Increasing the concentration of salt
B. Increasing the concentration of acid
C. Decreasing the concentration of salt
D. Independent of concentration of acid & salt
Answer: A
Clarification: An acid buffer is a mixture of weak acid and its salt with strong base, its pH increases by increasing the concentration of salt.

9. The buffer capacity is equal to __________
A. Δn / ΔpH
B. pH / Δn
C. ± 1pKa
D. ± 2pKa
Answer: A
Clarification: Buffer capacity = number of moles of acid or base added to 1 liter of buffer/change in pH.

10. Buffer capacity is maximum when __________
A. One mole of NH₄Cl is added to two moles of NH₄OH
B. One mole of NH₄Cl is added to one moles of NH₄OH
C. One mole of NH₄Cl is added to one mole of NaOH
D. One mole of NaCl is added to one mole of NaOH
Answer: B
Clarification: Buffer has more capacity when pH = pK_a.

of Biochemistry for Freshers, .

Biochemistry Multiple Choice Questions on “Regulation of Oxidative Phosphorylation”.

1. The regulation of oxidative phosphorylation depends on ____________
A. Magnitude of ion motive force
B. Magnitude of electron motive force
C. Magnitude of proton motive force
D. None of the mentioned
Answer: C
Clarification: The regulation of oxidative phosphorylation depends on the magnitude of proton motive force.

2. What is the rate of electron transfer when proton motive force is high?
A. Faster
B. Slower
C. Moderate
D. None
Answer: B
Clarification: When proton motive force is high, rate of electron transfer is slower.

3. The magnitude of proton motive force depends on ____________
A. Energy charge of cell
B. Permeability of membrane
C. Number of ribosomes in cell
D. None of the mentioned
Answer: A
Clarification: The magnitude of proton motive force depends on energy charge of cell.

4. Where does oxidative phosphorylation take place?
A. Ribosomes
B. Nucleus
C. Mitochondria
D. Cell membrane
Answer: C
Clarification: Oxidative phosphorylation takes place in mitochondria.

5. In metabolism, NAD is involved in ____________
A. Spontaneous reaction
B. Elimination reaction
C. Redox reactions
D. None of the mentioned
Answer: C
Clarification: NAD is involved in redox reactions.

6. NADP is a cofactor used in ____________
A. Catabolic reactions
B. Anabolic reactions
C. Elimination reaction
D. Redox reactions
Answer: B
Clarification: NADP is a cofactor used in anabolic reactions.

7. What is the proportion of ATP produced by oxidative phosphorylation?
A. 60%
B. 70%
C. 80%
D. 90%
Answer: A
Clarification: About 60% of ATP produced by oxidative phosphorylation.

8. NADP⁺ in its reduced form is ____________
A. NAD
B. NADH
C. NADPH
D. DPH
Answer: C
Clarification: NADPH is the reduced form of NADP⁺.

9. Products of glucose oxidation essential for oxidative phosphorylation are ____________
A. Pyruvate
B. Acetyl co-A
C. NADPH and ATP
D. NADH and FADH₂
Answer: D
Clarification: The end products of Krebs cycle are CO₂, NADH, FADH₂, ATP and water.
The reactants of oxidative phosphorylation are NADH, FADH₂, O₂, ADP and P.

10. Which effects the increased levels of hydrogen ions in the inter-membrane space of the mitochondria?
A. Increase ATP production
B. Decreased levels of oxidative phosphorylation
C. Increased levels of water in inter-membrane space
D. Decreased levels of chemiosmosis
Answer: A
Clarification: There is an increased ATP production if the levels of hydrogen ions increase in the inter-membrane space of the mitochondria.

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