Entry Test MCQ :: Enzymes

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11.

Which statement is incorrect about Lock and Key Model?

A.	Specific enzyme can transform only a specific substrate	B.	Active site of an enzyme is a non flexible structure.
C.	Active site does not change before during or even after the reaction.	D.	It explains the mechanism of every chemical reaction.

12.

The rate of reaction is directly proportional to the concentration of an enzyme which statement is incorrect in this respect:

A.	Increase in enzyme molecule increases the available active sites.	B.	This relation is for unlimited time period with unlimited enzyme concentration
C.	If the concentration is doubled the rate will become two fold.	D.	None of these.

13.

If the concentration of enzyme is kept constant and amount of substrate is increased a point is reached where increase in substrates concentration does not affect the reaction rate because of

A.	Enzymes get denatured at higher substrate conc.	B.	Rate of reaction is indirectly proportional to substrate concentration at this point.
C.	All the active sites on enzyme molecule are occupied.	D.	None of these.

14.

If more substrate to already occurring enzymatic reaction is added more enzyme activity is seen because:

A.	There is probably more substrate present than there is enzyme.	B.	There is probably more enzayme available than there is substrate.
C.	There is probably more product present than there is either substrate or enzyme.	D.	The enzyme substrate complex is probably failing to form during the reaction.

15.

If more substrate to already occurring enzymatic reaction is added and there is no effect on the rate of the reaction what is the form given to this situation:

A.	Saturation	B.	Denaturation
C.	Composition	D.	Inhibition

16.

The active site of an enzyme:

A.	Never changes	B.	Forms no chemical bond with substrate
C.	Determined by structure and the specificity of the enzyme.	D.	They are non specific in their action.

17.

Excessive increase in temperature of medium causes the enzyme molecule to

A.	Activate	B.	Unaffected
C.	Denatured	D.	None of these.

18.

Extreme change in pH results in:

A.	Change in ionization of amino acids at the active site of the enzyme.	B.	Change in the ionization of the substrate.
C.	Denaturation of the enzyme	D.	Increase in the reaction rate.

19.

Optimal temperature of enzymes present in human body is

A.	27?C	B.	37?C
C.	47?C	D.	30?C

20.

A chemical substance which can react (in place of substrate) with the enzyme but is not transformed into product/s and thus blocks the active site temporarily or permanently is called

A.	Co-enzyme	B.	Blocker
C.	Inhibitor	D.	Cofactor