NEET-UG Biology · Class 11
Factors affecting enzyme activity and inhibition — NEET & JEE Questions
Factors affecting enzyme activity and inhibition is a topic in Biomolecules, a Class 11 Biology chapter of the NEET-UG syllabus. TestBudy holds 12 published NEET-UG questions on Factors affecting enzyme activity and inhibition, each with the marking scheme of the real paper.
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Factors affecting enzyme activity and inhibition MCQs with solutions
10 of the 12 published questions on this topic, exactly as they appear in a test. Answers and worked solutions come with your result rather than on this page.
Enzyme activity is strongly influenced by
- A. temperature and pH
- B. atomic number only
- C. magnetic field only
- D. colour of the substrate only
Why does enzyme activity often fall sharply above an optimum temperature?
- A. The enzyme may denature and lose its functional conformation
- B. All substrate molecules disappear
- C. Activation energy becomes infinite
- D. Water stops moving
An enzyme has an optimum pH because
- A. ionisation states and structure of active-site groups depend on pH
- B. pH changes the atomic number of the enzyme
- C. pH affects only the colour of the solution
- D. enzymes function identically at all pH values
A competitive inhibitor generally reduces enzyme activity by
- A. competing with substrate for the active site
- B. destroying all substrate molecules
- C. binding only to DNA
- D. increasing substrate concentration automatically
An enzyme-catalysed reaction speeds up as substrate concentration rises, then approaches a maximum rate. The plateau occurs mainly because
- A. most active sites become occupied
- B. substrate concentration becomes zero
- C. the enzyme is converted into substrate
- D. temperature must fall to zero
An enzyme works best near pH 2 and loses activity near pH 8. Which conclusion is most reasonable?
- A. Its active conformation and catalytic groups are favoured in strongly acidic conditions
- B. It must be a lipid
- C. pH cannot affect enzymes
- D. It is necessarily inactive at all temperatures
A competitive inhibitor is added to an enzyme reaction. Which change can often partially overcome the inhibition?
- A. Increasing substrate concentration
- B. Removing all substrate
- C. Lowering enzyme concentration to zero
- D. Heating until the enzyme denatures
An enzyme solution is heated to 90°C and then cooled, but activity does not return. The most likely explanation is
- A. irreversible denaturation occurred
- B. the enzyme gained a new optimum at 90°C
- C. all enzymes are unaffected by heat
- D. substrate became an inhibitor permanently by definition
Two enzyme samples have the same substrate concentration. Sample P contains twice as much active enzyme as Q under otherwise identical, substrate-saturating conditions. Which rate comparison is most reasonable?
- A. P can have about twice the maximum rate of Q
- B. Both must have identical maximum rates
- C. Q must be twice as fast
- D. Enzyme concentration cannot affect rate
An inhibitor binds to a site different from the active site and changes enzyme conformation. Which description is most appropriate?
- A. Non-competitive or allosteric-type inhibition
- B. Competitive inhibition at the active site
- C. No inhibition is possible
- D. Substrate activation only
Common mistakes in Factors affecting enzyme activity and inhibition
Recorded against questions in this topic that are not shown above, so none of these points at an answer you can see on this page.
- Applies only the collision-rate effect and ignores denaturation at high temperature.
- Labels any reduced rate as non-competitive without considering how the effect changes with substrate concentration.
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