Biomolecules (Biology) · Question 52

Which one of the following statements is incorrect?

1. The competitive inhibitor does not affect the rate of breakdown of the enzyme-substrate complex.
2. The presence of the competitive inhibitor decreases the Km of the enzyme for the substrate.
3. A competitive inhibitor reacts reversibly with the enzyme to form an enzyme-inhibitor complex.
4. In competitive inhibition, the inhibitor molecule is not chemically changed by the enzyme.

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

1. Substrate binds with enzyme at its active site.
2. Addition of a lot of succinate does not reverse the inhibition of succinic dehydrogenase by malonate.
3. A non-competitive inhibitor binds the enzyme at a site distinct from that which binds the substrate.
4. Malonate is a competitive inhibitor of succinic dehydrogenase.

Which one of the following is a non-reducing carbohydrate?

1. Maltose
2. Sucrose
3. Lactose
4. Ribose 5-phosphate

A phosphoglyceride is always made up of

1. a saturated or unsaturated fatty acid esterified to glycerol molecule to which a phosphate group is also attached.
2. a saturated or unsaturated fatty acid esterified to a phosphate group which is also attached to a glycerol molecule.
3. only a saturated fatty acid esterified to a glycerol molecule to which a phosphate group is also attached.
4. only an unsaturated fatty acid esterified to a glycerol molecule to which a phosphate group is also attached.

Macromolecule chitin is

1. sulphur containing polysaccharide
2. simple polysaccharide
3. nitrogen containing polysaccharide
4. phosphorus containing polysaccharide.

Transition state structure of the substrate formed during an enzymatic reaction is

1. transient and unstable
2. permanent and stable
3. transient but stable
4. permanent but unstable.

The essential chemical components of many coenzymes are

1. carbohydrates
2. vitamins
3. proteins
4. nucleic acids.

Which of the following statements about enzymes is wrong?

1. Enzymes are denaturated at high temperatures.
2. Enzymes are mostly proteins but some are lipids also.
3. Enzymes are highly specific.
4. Enzymes require optimum pH and temperature for maximum activity.

Uridine, present only in RNA is a

1. nucleoside
2. nucleotide
3. purine
4. pyrimidine.

The figure shows a hypothetical tetrapeptide portion of a protein with parts labelled A - D. Which one of the following options is correct? [figure]

1. D is an acidic amino acid-glutamic acid.
2. C is an aromatic amino acid-tryptophan.
3. A is the C-terminal amino acid and D is N-terminal amino acid.
4. A is a sulphur containing amino acid methionine.