Enzymes Questions Set 2

Test Your Knowledge and master Biochemistry

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Biochemistry (Enzymes Set 2)

1 / 25

An enzyme catalyzing oxidoreduction, using oxygen as hydrogen acceptor is

A) Cytochrome oxidase

B) Lactate dehydrogenase

C) Malate dehydrogenase

D) Succinate dehydrogenase

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Coenzymes are

A) Heat stable, dialyzable, non protein organic molecules

B) Soluble, colloidal, protein molecules

C) Structural analogue of enzymes

D) Different forms of enzymes

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Factors affecting enzyme activity:

A) Concentration

B) pH

C) Temperature

D) All of these

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An enzyme which uses hydrogen acceptor
as substrate is

A) Xanthine oxidase

B) Aldehyde oxidase

C) Catalase

D) Tryptophan oxygenase

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Isoenzymes are

A) Chemically, immunologically and electrophoretically different forms of an enzyme

B) Different forms of an enzyme similar in all properties

C) Catalysing different reactions

D) Having the same quaternary structures like the enzymes

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An example of group transferring coenzyme is

A) NAD+

B) NADP+

C) FAD

D) CoA

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In competitive enzyme activity inhibition

A) The structure of inhibitor generally resembles that of the substrate

B) Inhibitor decreases apparent Km

C) Km remains unaffective

D) Inhibitor decreases Vmax without affecting Km

8 / 25

The pH optima of most of the enzymes is

A) Between 2 and 4

B) Between 5 and 9

C) Between 8 and 12

D) Above 12

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In non competitive enzyme activity inhibition, inhibitor

A) Increases Km

B) Decreases Km

C) Does not effect Km

D) Increases Km

10 / 25

The isoenzymes of LDH

A) Differ only in a single amino acid

B) Differ in catalytic activity

C) Exist in 5 forms depending on M and H monomer contents

D) Occur as monomers

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The enzyme using some other substance,
not oxygen as hydrogen acceptor is

A) Tyrosinase

B) Succinate dehydrogenase

C) Uricase

D) Cytochrome oxidase

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In competitive enzyme activity inhibition

A) Apparent Km is decreased

B) Apparent Km is increased

C) Vmax is increased

D) Vmax is decreased

13 / 25

Enzyme involved in joining together two
substrates is

A) Glutamine synthetase

B) Aldolase

C) Gunaine deaminase

D) Arginase

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The normal GPT activity ranges from

A) 60.0–250.0 IU/L

B) 4.0–17.0 IU/L

C) 3.0–15.0 IU/L

D) 0.1–14.0 IU/L

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Isoenzymes can be characterized by

A) Proteins lacking enzymatic activity that are necessary for the activation of enzymes

B) Proteolytic enzymes activated by hydrolysis

C) Enzymes with identical primary structure

D) Similar enzymes that catalyse different reaction

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Cocarboxylase is

A) Thiamine pyrophosphate

B) Pyridoxal phosphate

C) Biotin

D) CoA

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In enzyme kinetics Vmax reflects

A) The amount of an active enzyme

B) Substrate concentration

C) Half the substrate concentration

D) Enzyme substrate complex

18 / 25

The normal serum GOT activity ranges
from

A) 3.0–15.0 IU/L

B) 4.0–17.0 IU/L

C) 4.0–60.0 IU/L

D) 0.9–4.0 IU/L

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An example of hydrogen transferring
coenzyme is

A) CoA

B) NAD+

C) Biotin

D) TPP

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The normal value of CPK in serum varies
between

A) 4–60 IU/L

B) 60–250 IU/L

C) 4–17 IU/L

D) > 350 IU/L

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The normal serum acid phosphatase
activity ranges from

A) 5.0–13.0 KA units/100 ml

B) 1.0–5.0 KA units/100 ml

C) 13.0–18.0 KA units/100 ml

D) 0.2–0.8 KA units/100 ml

22 / 25

The normal serum alkaline phosphatase
activity ranges from

A) 1.0–5.0 KA units/100 ml

B) 5.0–13.0 KA units/100 ml

C) 0.8–2.3 KA units/100 ml

D) 13.0–21.0 KA units/100 ml

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A coenzyme containing non aromatic
hetero ring is

A) ATP

B) NAD

C) FMN

D) Biotin

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In enzyme kinetics Km implies

A) The substrate concentration that gives one half Vmax

B) The dissocation constant for the enzyme substrate comples

C) Concentration of enzyme

D) Half of the substrate concentration required to achieve Vmax

25 / 25

A coenzyme containing aromatic hetero
ring is

A) TPP

B) Lipoic acid

C) Coenzyme Q

D) Biotin

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The average score is 38%

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