Category: Biochemistry Objective Questions

Biochemistry Multiple Choice Questions on “Signaling in Microorganisms and Plants”.

1. Which of the following statements about Arabidopsis is not true?
A. In Arabidopsis, CTR-1 Ser/Thr protein kinase is activated by ethylene
B. Activation of MAPK cascade
C. EINI activation
D. Synthesis of ERF1 transcription factor
Answer: A
Clarification: In Arabidopsis, CTR-1 Ser/Thr protein kinase is inactivated by ethylene.

2. The 2-component system drives bacterial chemotaxis by coupling autophosphoryaltion of which receptor to phosphorylation of respective regulatory protein?
A. His kinase
B. Adenylyl cyclase
C. Guanylyl cyclase
D. None
Answer: A
Clarification: The 2-component system drives bacterial chemotaxis by coupling auto-phosphorylation of his kinase to phosphorylation of the respective regulatory protein.

3. Bacteria do not have which of the following receptors?
A. Adhesion receptors
B. Nuclear steroid receptors
C. Membrane proteins
D. GPCR
Answer: B
Clarification: Bacteria/plants do not have nuclear steroid receptors.

4. A factor involved in regulating the fate of stem cells in plant development is _________
A. Adrenaline
B. Epinephrine
C. Thyroid stimulating hormone
D. CLV1
Answer: D
Clarification: Adrenaline, epinephrine and thyroid stimulating hormones are animal hormones.

5. The peptide trigger for the self-incompatibility response that prevents self-pollination is _________
A. Salicylic acid
B. Jasmonates
C. Brassinosteroids
D. Plant peptide hormones
Answer: C
Clarification: Brassinosteroids prevents self-pollination.

6. Autophosphorylation is done on _________
A. His residues
B. Ser/Thr residues
C. Cys residues
D. Lys residues
Answer: B
Clarification: Autophosphorylation is done on Ser/Thr residues.

7. In Arabidopsis flg22 binds to _________
A. FLS2
B. LPS
C. BAK1
D. MAPK
Answer: A
Clarification: flg22 present in plants binds to FLS2.

8. Transcription factor in plants is _________
A. Serine
B. Threonine
C. WRKY22/29
D. Leucine
Answer: C
Clarification: Serine, threonine and leucine are amino acids.

9. Negative regulator of ethylene response is _________
A. LPS
B. CTR1
C. BAK1
D. MAPK
Answer: B
Clarification: CTR1 is the negative regulator of ethylene response.

10. ERF1is a _________
A. Translation terminating factor
B. Positive regulator
C. Translation promoting factor
D. Enzyme inhibitor
Answer: A
Clarification: ERF1 is a eukaryotic translation terminating factor.

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Biochemistry Multiple Choice Questions on “From Genes to Genomes-1”.

1. cDNA, a term used in recombinant DNA technology means ____________
A. Competitive DNA
B. Chemical DNA
C. Complex DNA
D. Complementary DNA
Answer: D
Clarification: Complementary DNA is also termed as cDNA.

2. The process of introduction of foreign DNA into an animal cell is called ____________
A. Transversion
B. Conversion
C. Inversion
D. Transfection
Answer: D
Clarification: Transfection is the deliberate inducing of foreign DNA into an animal cell.

3. A segment of DNA that reads from the same forward and backward is called ____________
A. Palindromic DNA
B. Complementary DNA
C. Plasmid DNA
D. Copy DNA
Answer: A
Clarification: A palindromic sequence is the same when read from 5’ to 3’ on one strand and 3’ to 5’ on its complementary strand.

4. Which of the following enzyme is used in PCR?
A. Taq DNA polymerase
B. HRP
C. EcoRI
D. EcoRII
Answer: A
Clarification: HRP is an enzyme used in ELISA. EcorI and EcorII are the restriction enzymes.
So only a DNA polymerase is responsible for producing multiple copies of DNA sequence.

5. Which of the following is helpful in distinguishing DNA of one individual from another?
A. PCR
B. Reverse transcriptase
C. cDNA
D. RFLP
Answer: D
Clarification: Restriction fragment length polymorphism (RFLP) is helpful in distinguishing one individual from another.

6. Which of the following is the correct order of organization of genetic material from largest to smallest?
A. Genome, chromosome, gene, nucleotide
B. Nucleotide, gene, chromosome, genome
C. Gene, nucleotide, chromosome, genome
D. Chromosome, genome, nucleotide, gene
Answer: A
Clarification: Group of nucleotides makes up a gene, these genes make up a chromosome and these chromosomes make up to genome.

7. Which of the following codons is not a termination codon for protein synthesis?
A. UUU
B. UAG
C. UAA
D. UGA
Answer: A
Clarification: After the ribosome reaches the codon UAG or UAA or UGA on m-RNA strand, protein synthesis is terminated.

8. Which of the following are the two methods of screening?
A. Hybridization and PCR
B. ELISA and blotting
C. ELISA and PCR
D. PCR and RFLP
Answer: A
Clarification: Hybridization and PCR are the two methods of screening.

9. Short sub-sequence of a cDNA sequence is ____________
A. Expressed sequence tag
B. Sequence tagged site
C. Contig
D. YAC
Answer: A
Clarification: Sequence tagged site is a short DNA sequence having single occurrence in genome.
Cotig is a set of overlapping DNA segments that together represent a consensus region of DNA.
YAC is a linear DNA molecule.

10. Short DNA sequence having single occurrence in genome is ____________
A. Expressed sequence tag
B. Sequence tagged site
C. Contig
D. YAC
Answer: B
Clarification: Expressed sequence tag is a short sub-sequence of a cDNA sequence.
Cotig is a set of overlapping DNA segments that together represent a consensus region of DNA.
YAC is a linear DNA molecule.

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Biochemistry Multiple Choice Questions on “Protein Tertiary and Quaternary Structures”.

1. Fibroin is rich in ________
A. Alanine and Glycine
B. Alanine
C. Glycine
D. Pro
Answer: A
Clarification: Fibroin is rich in Alanine and Glycine residues, permitting a close packing of β sheets and an interlocking arrangement of R groups.

2. Which of the following bonds are not involved in tertiary type of protein structure?
A. Disulfide bond
B. Hydrogen bonding
C. Salt bridges
D. Hydrophilic interactions
Answer: D
Clarification: Hydrophobic interactions are present in tertiary type of protein structure.

3. Which of the following does not possess a quaternary structure?
A. Myoglobin
B. Lactate dehydrogenase
C. Immunoglobin M
D. Creatine Phospho Kinase
Answer: A
Clarification: Myoglobin is a monomer, so it does not possess a quaternary structure.

4. Which of the following is abundantly found in collagen?
A. Glycine
B. Serine
C. Alanine
D. Tryptophan
Answer: A
Clarification: Each three amino acids of the collagen peptide chain is a glycine. It is thus an abundant amino acid that is important for collagen structure.

5. Which of the following is first determined as oligomer?
A. Myoglobin
B. Collagen
C. Keratin
D. Hemoglobin
Answer: D
Clarification: Hemoglobin contains four polypeptide chains and four heme prosthetic groups in which iron atoms are present in Fe⁺² state.

6. Which of the following is false?
A. Lysozyme has S-S linkage
B. Ribonuclease has S-S linkage
C. Heme group in cytochrome c is covalently linked to the protein on two sides
D. Ribonuclease has SH-SH linkage
Answer: D
Clarification: Lysozyme and ribonuclease have disulfide linkages.

7. Which of the following enzyme is secreted by the pancreas?
A. Ribonuclease
B. Lysozyme
C. Cytochrome c
D. Myoglobin
Answer: A
Clarification: Ribonuclease is secreted by the pancreas into small intestine, where it catalyses the hydrolysis of certain bonds in ribonucleic acids present in the ingested food.

8. Which of the following is a component of mitochondria?
A. Ribonuclease
B. Lysozyme
C. Cytochrome c
D. Myoglobin
Answer: C
Clarification: Cytochrome c which is a heme protein is a component of the respiratory chain of mitochondria.

9. Which of the following serves as bactericidal agent?
A. Ribonuclease
B. Lysozyme
C. Cytochrome c
D. Myoglobin
Answer: B
Clarification: Lysozyme can lyse, or degrade bacterial cell walls, so it serves as a bactericidal agent.

10. Which of the following is false about fibrous protein?
A. It is in rod or wire like shape
B. Keratin and collagen are the best examples
C. Hemoglobin is the best example
D. It provides structural support for cells and tissues
Answer: C
Clarification: Hemoglobin is the best example of globular protein.

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Biochemistry Multiple Choice Questions on “Biosynthesis of Membrane Phospholipids”.

1. Displacement of CMP through nucleophilic attack by the hydroxyl group of serine yields ___________
A. Phosphatidyl serine
B. Phosphatidyl glycerol 3-phosphate
C. Phosphatidyl glycerol
D. Phosphatidylethanolamine
Answer: A
Clarification: Displacement of CMP through nucleophilic attack by the hydroxyl group of serine yields phosphatidyl serine.

2. Displacement of CMP through a nucleophilic attack by the hydroxyl group of C-1 hydroxyl of glycerol 3-phosphate yields ___________
A. Phosphatidyl serine
B. Phosphatidyl glycerol 3-phosphate
C. Phosphatidyl glycerol
D. Phosphatidylethanolamine
Answer: B
Clarification: Displacement of CMP through nucleophilic attack by the hydroxyl group of C-1 hydroxyl of glycerol 3-phosphate yields phosphatidyl glycerol 3-phosphate.

3. Which of the following is a molecular formula of cholesterol?
A. C₂₇H₄₅OH
B. C₂₈H₄₅OH
C. C₂₉H₄₅OH
D. C₂₃H₄₅OH
Answer: A
Clarification: C₂₇H₄₅OH is the molecular formula of cholesterol.

4. Which of the following is involved in the bio-signaling pathway that includes membrane turnover and exocytosis?
A. Phosphatidylinositol
B. Phosphatidyl glycerol
C. Myoinositol
D. Phosphatidyl glycerol and myoinositol
Answer: A
Clarification: Phosphatidylinositol is involved in the bio-signaling pathway that includes membrane turnover and exocytosis.

5. The precursor of eicosanoids in human is ___________
A. Ceramide
B. Arachidonic acid
C. Cholesterol
D. Squaline
Answer: B
Clarification: The precursor of eicosanoids in human is arachidonic acid.

6. Which of the following is the simplest hydrophilic moiety present in membrane lipids?
A. Glucose
B. Amino group
C. Hydroxyl group
D. Phosphate group
Answer: C
Clarification: Hydroxyl group is the simplest hydrophilic moiety present in membrane lipids.

7. Which of the following is considered as the structural parent of all sphingolipids?
A. Sphingosine
B. Ceramide
C. Lecithin
D. Sphingomyelin
Answer: B
Clarification: N-acyl fatty acid derivative of sphingosine at C2 is called ceramide, which forms the backbone of sphingolipids.

8. The most complex sphingolipid is ___________
A. Cerebroside
B. Gangleoside
C. Globoside
D. Ceramide
Answer: B
Clarification: Gangleosides have the most complex structure.

9. Phosphatidylserine is derived only from ___________
A. Phosphatidylethanolamine
B. Phosphatidyl glycerol
C. Phosphatidyl choline
D. CDP-diacylglycerol
Answer: A
Clarification: Decarboxylation of phosphatidylserine produces phosphatidylethanolamine.

10. Cerebroside is also called as ___________
A. Sphingomyelin
B. N-acylsphingosine
C. Sphinganine
D. Gangliosides
Answer: A
Clarification: Cerebroside is also called as sphingomyelin.

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Biochemistry Questions on “Coordinated Regulation of Glycogen Synthesis and Breakdown”.

1. Glucagon and epinephrine stimulate glycogen breakdown to glucose 6-phosphate ________
A. Directly by binding to glycogen phosphorylase
B. Indirectly by first stimulating adenylate cyclase to make cAMP
C. Only in the liver
D. Only in muscle cells

Answer: B
Clarification: The second messenger cAMP increases in concentration in response to stimulation by epinephrine in muscle or glucagon in liver.

2. Which compounds are responsible for the coordinated regulation of glucose and glycogen metabolism?
A. NADH
B. NAD⁺
C. Acetyl co-A
D. Fructose 2, 6-bisphosphate

Answer: D
Clarification: The hormonal regulation of glycolysis and gluconeogenesis is mediated by fructose 2, 6-bisphosphate.

3. Glycogen synthase a is activated by ___________
A. Phosphorylation catalyzed by GSK3
B. Dephosphorylation catalyzed by GSK3
C. Phosphorylation catalyzed by pyruvate kinase
D. Phosphorylation catalyzed by pyruvate carboxylase

Answer: A
Clarification: A protein kinase (PDK-1) that is activated when bound to PIP3 activates a second protein kinase (PKB. which phosphorylates glycogen synthase kinase 3 (GSK-3). The inactivation of GSK3 allows PP1 to dephosphorylate glycogen synthase converting it to its active form.

4. Glucagon is released from ___________
A. Muscle
B. Pancreas
C. Kidneys
D. Epithelial tissues

Answer: B
Clarification: Glucagon is released from pancreas and causes the liver to convert glycogen to glucose.

5. Glucose 6-phosphatase is present only in ___________
A. Liver
B. Muscle
C. Epithelial tissues
D. Kidneys

Answer: A
Clarification: Glucose 6-phosphatase which hydrolyzes glucose 6-phosphate is present only in liver. Other tissues lack glucose 6-phosphatase.

6. Which of the following enzymes is involved in the positive regulation of glycolysis/gluconeogenesis?
A. Hexokinase II
B. Hexokinase IV
C. PFK-2/FBPase-2
D. Pyruvate kinase

Answer: C
Clarification: Increased expression of PFK-2/FBPase-2 regulates glycolysis/gluconeogenesis.

7. Which of the following enzymes is involved in fatty acid synthesis?
A. Hexokinase II
B. Hexokinase IV
C. PFK-2/FBPase-2
D. Pyruvate dehydrogenase

Answer: D
Clarification: Hexokinase II and hexokinase IV involved in glycolysis.

8. Which of the following is involved in triacylglycerol synthesis?
A. Hexokinase II
B. Acyl co-A glycerol transferases
C. PFK-2/FBPase-2
D. Pyruvate dehydrogenase

Answer: B
Clarification: Hexokinase II involved in glycolysis, pyruvate dehydrogenase involved in fatty acid synthesis.

9. Which of the following is involved in pentose phosphate pathway?
A. Glucose 6-phosphate dehydrogenase
B. Acyl co-A glycerol transferases
C. PFK-2/FBPase-2
D. Pyruvate dehydrogenase

Answer: A
Clarification: Acyl co-A glycerol transferases involved in triacylglycerol synthesis, pyruvate dehydrogenase involved in fatty acid synthesis.

10. Which of the following enzyme’s gene expression is slowed by insulin?
A. Hexokinase II
B. Hexokinase IV
C. PEP carboxykinase
D. Pyruvate kinase

Answer: C
Clarification: Insulin stimulates the transcription of the genes that encode hexokinase II, hexokinase IV and pyruvate kinase.

Biochemistry Multiple Choice Questions on “Multivalent Scaffold Proteins and Membrane Rafts”.

1. The specificity of signaling pathways does not include ___________
A. Migration of signal proteins into membrane rafts
B. Assembly of large multiprotein complexes
C. Phosphorylation of target proteins at Ser, Thr/Tyr residues
D. Flippase-catalyzed movement of phospholipids from the inner to the outer leaflet
Answer: D
Clarification: The specificity of signaling pathways does not include flippase-catalyzed movement of phospholipids from the inner to the outer leaflet.

2. Which of the following directly phosphorylate tyrosines to start a kinase protein enzymatic cascade?
A. Receptor tyrosine kinase
B. Receptor guanylyl cyclases
C. Receptor serine kinase
D. Receptor threonine kinase
Answer: A
Clarification: Only receptor tyrosine kinase directly phosphorylates tyrosine to start a kinase protein enzymatic cascade.

3. PTB domains bind to ___________
A. Phosphorylated tyrosine
B. Phosphoryated threonine
C. Phosphorylated serine
D. Phosphorylated cysteine
Answer: A
Clarification: Phosphotyrosine binding domain binds to phosphotyrosine.

4. Scaffold protein in insulin signal transduction ___________
A. KSR
B. IRS-1
C. MEKK1
D. AKAP
Answer: B
Clarification: IRS-1 is an adapter protein in insulin that codes for IRS1 gene.

5. Which of the following is involved in extrinsic cell death pathway?
A. Heterotrimeric G protein complex
B. TRADD
C. IRS-1
D. Protein-kinase A
Answer: B
Clarification: TRADD, tumor necrosis factor receptor type 1-associated death domain protein is involved in extrinsic cell death pathway.

6. Which of the following converts GTP to cGMP to start its enzymatic cascade?
A. Receptor guanylyl cyclase
B. Receptor adenylyl cyclase
C. Calmodulin
D. Protein kinase-A
Answer: A
Clarification: Receptor adenylyl cyclase converts ATP to cAMP.

7. Which of the following are stimulated to become membrane associated upon binding of insulin to the insulin receptor?
A. PH-domain
B. PTB
C. SH3
D. SH2
Answer: A
Clarification: PH domain is stimulated to become membrane associated upon binding of insulin to the insulin receptor.

8. Which of the following is involved in phospho-tyrosine binding?
A. SH2
B. SH3
C. PTB
D. PH
Answer: A
Clarification: SH3 is involved in proline rich motif binding.

9. Which of the following is involved in proline rich motif binding?
A. SH2
B. SH3
C. PTB
D. PH
Answer: B
Clarification: SH2 is involved in phospho-tyrosine binding.

10. Which of the following is not a downstream component?
A. Ras
B. MEK
C. ERK
D. PIP3
Answer: D
Clarification: Ras, MEK and ERK are the downstream components.

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