Which of the following statements regarding enzyme inhibition is correct?

Select the option which is not correct with respect to enzyme action.

Which one of the following statement is incorrect ?

1. A competitive inhibitor reacts reversibly with the enzyme to form an enzyme-inhibitor.

2. In competitive inhibition the inhibitor molecule is not chemically changed by the

enzyme.

3. The competative inhibitor does not affect the rate of breakdown of the enzyme-

substrate complex.

4. The presence of the competitive inhibitor decreases the k_m of the enzyme for the

substrate.

A competive inhibitor of succinic dehydrogenase is

1. malonate                 

2. oxaloacetate

3. $\mathrm{\alpha }$-ketoglutarate       

4. malate

The inhibition of succinic dehydrogenase by malonate is an example of

1. competitive inhibition

2. non-competitive inhibition

3. allosteric modulation

4. none of the above

An example of the competitive inhibition of an enzyme is the inhibition of:

1. succinic dehydrogenase by malonic acid

2. cytochrome oxidase by cyanide

3. hexokinase by glucose -6-phosphate

4. carbonic anhydrase by carbondioxide

In competitive inhibition:

1. Inhibitor resembles the substrate in molecular structure

2. Competition between substrates and inhibitors to occupy active sites

3. Binding the inhibitors to active sites declines the enzyme action

4. All are correct

The adjoining graph shows change in conc. of substrate on enzyme activity. Identify A, B and C:

A competitive inhibitor of succinic dehydrogenase is: