question_answer 1) Feed back inhibition of an enzymatic reaction is caused by: [AIPMT 2000]
A)
substrate
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B)
enzyme
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C)
end product
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D)
rise in temperature
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question_answer 2) Enzymes enhance the rate of a reaction by: [AIPMT 2000]
A)
lowering the activation energy of the reaction
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B)
combining with the product as soon as it is formed
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C)
forming a reactant-product complex
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D)
changing the equilibrium point of the reaction
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question_answer 3) Hydrolytic enzymes, which act at low pH are called as: [AIPMT 2002]
A)
proteases
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B)
\[\alpha \]-amylases
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C)
hydrolases
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D)
peroxidases
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question_answer 4) In which one of the following enzymes, copper is necessarily associated as an activator? [AIPMT (S) 2004]
A)
Carbonic anhydrase
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B)
Tryptophanase
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C)
Lactic dehydrogenase
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D)
Tyrosinase
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question_answer 5) Which one of the following hydrolyses internal phosphodiester bonds in a polynucleotide chain? [AIPMT (S) 2005]
A)
Lipase
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B)
Exonuclease
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C)
Endonuclease
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D)
Protease
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question_answer 6) G-6-P dehydrogenase deficiency is associated with haemolysis of: [AIPMT (S) 2005]
A)
lymphocytes
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B)
RBCs
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C)
platelets
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D)
leucocytes
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question_answer 7) Enzymes, vitamins and hormones can be classified into a single category of biological chemicals, because all of these: [AIPMT (S) 2005]
A)
enhance oxidative metabolism
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B)
are conjugated proteins
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C)
are exclusively synthesized in the body of a living organism as at present
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D)
help in regulating metabolism
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question_answer 8) Which of the following statements regarding enzyme inhibition is correct? [AIPMT (S) 2005]
A)
Non-competitive inhibition of an enzyme can he overcome by adding large amount of substrate
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B)
Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein
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C)
Competitive inhibition is seen when the substrate and the inhibitor compete
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D)
Non-competitive inhibitors often bind to the enzyme irreversibly
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question_answer 9) The catalytic efficiency of two different enzymes can be compared by the: [AIPMT (S) 2005]
A)
the Revalue
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B)
the pH optimum value
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C)
formation of the product
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D)
None of thise
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question_answer 10) An organic substance bound to an enzyme and essential for its acvity is called: [AIPMT (S) 2006]
A)
coenzyme
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B)
holoenzyme
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C)
apoenzyme
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D)
isoenzyme
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question_answer 11) An enzyme that can stimulate germination of barley seeds is: [AIPMT (S) 2006]
A)
\[\alpha \]-amylase
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B)
lipase
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C)
protease
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D)
invertase
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question_answer 12) Lysozyme that is present in perspiration, saliva and tears, destroys: [AIPMT (S) 2007]
A)
certain fungi
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B)
certain types of bacteria
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C)
all viruses
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D)
most virus-infected cells
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question_answer 13) All enzymes of TCA cycle are located in the mitochondrial matrix except one which is located in inner mitochondrial membranes in eukaryotes and in cytosol in prokaryotes. This enzyme is: [AIPMT (S) 2007]
A)
lactate dehydrogenase
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B)
isocitrate dehydrogenase
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C)
malate dehydrogenase
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D)
succinate dehydrogenase
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question_answer 14) Modem detergents contain enzyme preparations of [AIPMT (S) 2008]
A)
acidophiles
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B)
alkaliphiles
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C)
thermoacidophiles
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D)
thermophiles
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question_answer 15) A competitive inhibitor of succinic dehydrogenase is [AIPMT (S) 2008]
A)
malonate
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B)
oxaloacetate
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C)
\[\text{ }\!\!\alpha\!\!\text{ -}\]ketoglutarate
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D)
malate
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question_answer 16) Which one of the following is resistant to enzyme action? [AIPMT (S) 2008]
A)
Cork
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B)
Wood fibre
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C)
Pollen exine
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D)
Leaf cuticle
done
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question_answer 17) Which one of the following pairs is wrongly matched? [AIPMT (S) 2009]
A)
done
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B)
Alcohol Nitrogenase
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C)
done
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D)
done
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question_answer 18)
The figure given below shows the conversion of a substrate into product by an enzyme. In which one of the four options (a-d), the components of reaction labelled as A, B, C and D are identified correctly? [AIPMT (M) 2010]
A)
Potential energy Transition state Activation energy with enzyme Activation energy without enzyme
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B)
Transition energy Potential energy Activation energy without enzyme Activation energy with enzyme
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C)
Potential energy Transition state Activation energy with enzyme Activation energy without enzyme
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D)
Activation energy with enzyme Transition state Activation energy without enzyme Potential energy
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question_answer 19) Three of the following statements about enzymes are correct and one is wrong. Which one is wrong? [AIPMT (M) 2010]
A)
Enzymes require optimum pH for maximal activity
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B)
Enzymes are denatured at high temperature but in certain exceptional organisms they are effective even at temperatures \[80{}^\circ -90{}^\circ C\]
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C)
Enzymes are highly specific
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D)
Most enzymes are proteins but some are lipids
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question_answer 20)
The curve given below shows enzymatic activity with relation to three conditions (pH, temperature and substrate concentration) [AIPMT (S) 2011] What do the two axises (X and Y) represent?
A)
temperature enzyme activity
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B)
substrate concentration enzymatic activity
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C)
enzymatic activity temperature
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D)
done
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question_answer 21) For its activity, carboxypeptidase requires [AIPMT (M) 2012]
A)
zinc
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B)
iron
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C)
niacin
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D)
copper
done
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question_answer 22) Transition state structure of the substrate formed during an enzymatic reaction is [NEET 2013]
A)
transient but stable
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B)
permanent but unstable
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C)
transient and unstable
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D)
permanent and stable
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question_answer 23) Which of the following is not correctly matched for the organism and its cell wall degrading enzyme? [NEET 2013]
A)
done
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B)
done
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C)
Algae Methylase
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D)
done
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question_answer 24) The essential chemical components of many coenzymes are [NEET 2013]
A)
proteins
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B)
nucleic acids
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C)
carbohydrates
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D)
vitamins
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question_answer 25) Select the option which is not correct with respect to enzyme action. [NEET 2014]
A)
Substrate binds with enzyme as its active site
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B)
Addition of lot of succinate does not reverse the inhibition of succinic dehydrogenase by malonate
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C)
A non-competitive inhibitor binds the enzyme at a site distinct from that which binds the substrate
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D)
Malonate is a competitive inhibitor of succinic dehydrogenase
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question_answer 26) The enzyme recombinase is required at which stage of meiosis? [NEET 2014]
A)
Pachytene
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B)
Zygotene
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C)
Diplotene
done
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D)
Diakinesis
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question_answer 27) Which one of the following statements is incorrect? [NEET 2015]
A)
A competitive inhibitor reacts reversibly with the enzyme to form an enzyme-inhibitor.
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B)
In competitive inhibition the inhibitor molecule is not chemically changed by the enzyme.
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C)
The competitive inhibitor does not affect the rate of breakdown of the enzyme-substrate complex.
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D)
The presence of the competitive inhibitor decreases the km of the enzyme for the substrate.
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question_answer 28) A non - proteinaceous enzyme is [NEET - 2016 Phase-II]
A)
Lysozyme
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B)
Ribozyme
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C)
Ligase
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D)
Deoxyribonuclease
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question_answer 29)
Which of the following describes the given graph correctly? [NEET - 2016 Phase-II]
A)
Endothermic reaction with energy A in presence of enzyme and B in absence of enzyme
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B)
Exothermic reaction with energy A in presence of enzyme and B in absence of enzyme
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C)
Endothermic reaction with energy A in absence of enzyme and B in presence of enzyme
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D)
Exothermic reaction with energy A in absence of enzyme and B in presence of enzyme
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question_answer 30) Which one of the following statements is correct, with reference to enzymes? [NEET-2017]
A)
Holoenzyme = Coenzyme + Cofactor
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B)
Apoenzyme = Holoenzyme + Coenzyme
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C)
Holoenzyme = Apoenzyme + Coenzyme
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D)
Coenzyme = Apoenzyme + Holoenzyme
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question_answer 31)
Consider the following statements:[NEET 2019] [A] Coenzyme of metal ion that is tightly bound to enzyme protein is called prosthetic group. [B] A complete catalytic active enzyme with its bound prosthetic group is called apoenzyme Select the correct option-
A)
Both [A] and [B] are false
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B)
[A] is false but [B] is true
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C)
Both [A] and [B] are true
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D)
[A] is true but [B] is false
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