Biomolecules MCQs | Biomolecules Objective Type Questions and Answers

(1) Platelet aggregation:
[A] is initiated at the site of an injury by conversion of fibrinogen to fibrin
[B] is inhibited in uninjured blood vessels by the secretion of prostacyclin by intact vascular endothelium
[C] causes morphological changes and a release of the vasodilator serotonine
[D] is inhibited by the release of ADP and thromboxane A2
Answer: is inhibited by the release of ADP and thromboxane A2
(2) The cones of the retina:
[A] are responsible for colour vision
[B] are much more numerous than rods
[C] have red, blue and green light- sensitive pigments that differ because of small difference in the retinal prosthetic group
[D] do not use transducin in signal transduction
Answer: are responsible for colour vision
(3) The nerve impulse that initiates muscular contraction
[A] begins with the binding of acetyl choline to receptors in the sarcoplasmic reticulum
[B] causes both the plasma membrane and the transverse tubules to undergo hyperpolariation
[C] causes opening of calcium channels which lead to an increase in calcium contreation within the sarcomere
[D] prevents sodium entering the sarcomere
Answer: causes opening of calcium channels which lead to an increase in calcium contreation within the sarcomere
(4) When a muscle contracts, the
[A] Transverse tubules shorten, the myofibrils and sarcoplasmic reticulum close together
[B] Thin filaments and thick filaments of the sarcomere shorten
[C] Light chains dissociate from the heavy chains of myosin
[D] H bands and I bands of the sarcomere shorten because the thin filaments and thick filaments side past each other
Answer: H bands and I bands of the sarcomere shorten because the thin filaments and thick filaments side past each other
(5) Lysis of a fibrin clot:
[A] is an equibrium wwith formation of the clot
[B] begins when plasmin binds to the clot
[C] requires the hydrolysis of plasminogen into heavy and light chains
[D] requires conversion of plasminogen by tissue plasminogen activator
Answer: requires conversion of plasminogen by tissue plasminogen activator
(6) ATP concentration is maintained relatively constant during muscle contraction by
[A] increasing the metabolic activity
[B] the action of adenylate kinase
[C] theaction of creatne phosphokinase
[D] all of the above
Answer: all of the above
(7) 4-hydroxy proline is present in
[A] Collagen
[B] Plant cell wall
[C] Keratin
[D] Both plant cell wall and collagen
Answer: Both plant cell wall and collagen
(8) Peptide bonds between amino acids are highly stable and have a half-life of seven years in intracellular condition. This is due to
[A] High activation energy required for hydrolysis
[B] Low activation energy required for hydrolysis
[C] Peptide bond is a covalent bond
[D] Peptide bond is rigid and planar
Answer: High activation energy required for hydrolysis
(9) Tri-peptide consists
[A] 3 amino acids and 3 peptide bonds
[B] 2 amino acids and 3 peptide bonds
[C] 3 amino acids and 2 peptide bonds
[D] 3 amino acids and 4 peptide bonds
Answer: 3 amino acids and 2 peptide bonds
(10) All the following statements are true except
[A] Ornithine and citrulline are uncommon aminoacids
[B] Ornithine is an intermediates in Urea cycle
[C] Ormithine and citrulline are uncommon amino acids present in many proteins
[D] Both ornithine and citrulline are intermediates in urea cycle
Answer: Ormithine and citrulline are uncommon amino acids present in many proteins
(11) The characteristic strong absorbance of 280nm of proteins is due to
[A] All amino acids can absorb at 280nm
[B] Only Tryptophan and tyrosine can absorb at 280 nm
[C] Tryptophan is responsible for the absorbance
[D] Tryptophan, tyrosine and phenylalanine can absorb at 280 nm
Answer: Tryptophan, tyrosine and phenylalanine can absorb at 280 nm
(12) The formation of cystine occurs at
[A] ER
[B] Golgi
[C] Cytosol
[D] Mitochondria
Answer: ER
(13) Which of the following interaction contributes most in protein folding

[A] Covalent bond
[B] Ionic bond
[C] Hydrophobic interaction
[D] Vander walls interaction
Answer: Hydrophobic interaction
(14) Which of the following aminoacid has pKa near neutrality
[A] Tryptophan
[B] Arginine
[C] Histidine
[D] Asparagine
Answer: Histidine
(15) Desmosine is an unusual amino acid found in
[A] Myosin
[B] Troponin
[C] Actin
[D] Elastin
Answer: Elastin
(16) How many small peptides are formed upon cleavage by trypsin if a protein has 5 lysine residues
[A] 4
[B] 5
[C] 6
[D] 7
Answer: 6
(17) EF-1α and EF-Tu are
[A] Analogs
[B] Homologs
[C] Paralogs
[D] Syllogs
Answer: Homologs
(18) All the statements regarding peptide bond are true except
[A] Peptide bond is a co-valent bond
[B] Peptide bond is rigid and planar
[C] Peptide bond has partial double bond character
[D] Peptide bond is formed by non-condensation reaction
Answer: Peptide bond is formed by non-condensation reaction
(19) Αlpha-helix has
[A] 3.6 residues/turn and is a right handed helix
[B] 3.8 residues/turn and is a right handed helix
[C] 3.6 residues/turn and is a left handed helix
[D] 3.8 residues/turn and is a left handed helix
Answer: 3.6 residues/turn and is a right handed helix
(20) Which of the following amino acids are rarely present in alpha helix
[A] Glycine and proline
[B] Proline and tryptophan
[C] Tryptophan and glycine
[D] Proline only
Answer: Glycine and proline

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