Biomolecules (Biology) · Question 69

Three of the following statements about enzymes are correct and one is wrong. Which one is wrong?

1. Enzymes require optimum pH for maximal activity.
2. Enzymes are denatured at high temperature but in certain exceptional organisms they are effective even at temperatures 80 –90 .
3. Enzymes are highly specific.
4. Most enzymes are proteins but some are lipids.

The figure given below shows the conversion of a substrate into product by an enzyme. In which one of the four options (1 – 4) the components of reaction labelled as A, B, C and D are identified correctly? [figure]

1. array|l|l|l|l| A & B & C & D \ Potential energy & Transition state & Activation energy & Activation energy without enzyme \ array
2. array|l|l|l|l| A & B & C & D \ Transition state & Potential energy & Activation energy without enzyme & Activation energy with enzyme \ array
3. array|l|l|l|l| A & B & C & D \ Potential energy & Transition state & Activation energy with enzyme & Activation energy without enzyme \ array
4. array|l|l|l|l| A & B & C & D \ Activation energy with enzyme & Transition state & Activation energy without enzyme & Potential energy \ array

Carbohydrates are commonly found as starch in plant storage organs. Which of the following five properties of starch (A – E) make it useful as a storage material? The useful properties are

1. (A), (C) and (E)
2. (A) and (E)
3. (B) and (C)
4. (B) and (D)

A competitive inhibitor of succinic dehydrogenase is

1. -ketoglutarate
2. malate
3. malonate
4. oxaloacetate

About 98 percent of the mass of every living organism is composed of just six elements including carbon, hydrogen, nitrogen, oxygen and

1. sulphur and magnesium
2. magnesium and sodium
3. calcium and phosphorus
4. phosphorus and sulphur

An organic substance bound to an enzyme and essential for its activity is called

1. isoenzyme
2. coenzyme
3. holoenzyme
4. apoenzyme

The catalytic efficiency of two different enzymes can be compared by the

1. formation of the product
2. pH of optimum value
3. Km value
4. molecular size of the enzyme.

Which one of the following statements regarding enzyme inhibition is correct?

1. Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein.
2. Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme.
3. Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate.
4. Non-competitive inhibitors often bind to the enzyme irreversibly.

Enzymes, vitamins and hormones can be classified into a single category of biological chemicals, because all of these

1. help in regulating metabolism
2. are exclusively synthesized in the body of a living organism as at present
3. are conjugated proteins
4. enhance oxidative metabolism.

Which of the following is the simplest amino acid?

1. Alanine
2. Asparagine
3. Glycine
4. Tyrosine