Which of the following is incorrect?

1. The hair protein, keratin, is synthesized from the amino acid methionine

2. Phospholipids act as carriers of small non polar molecules across the cell membrane

3. Dietary intake of PUFA decreases the serum cholesterol level in our body

4. Cobalt is a constituent of Vit B₁₂

Which of the following vitamins is a coenzyme for amino acid and fatty acid metabolism?

1. Vitamin B₆               

2. Vitamin B₁₂

3. Vitamin B₁               

4. Vitamin B₂

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

In RNA thymine is replaced by

1. uracil                           

2. adenine

3. thiamine                       

4. guanine

The vitamin nicotinamide can be synthesized in our body from.

1. tyrosine

2. tryptophan

3. valinc

4. phenylalanine

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 which one of the following sets of three items each belong to the category mentioned against them?

(1) Lysine, glycine, thiamine - amino acids

(2) Myosin, oxytocin and gastrin -hormones

(3) Rennin, helicase and hyaluronidase - enzymes

(4) Optic nerve, oculomotor, vagus - sensory nerves

The figure given below shows three velocity substrate concentration curves for an enzyme reaction. What do the curves a, b,  and c depict respectively?

(1) a - normal enzyme reaction

     b - competitive inhibition

     c - non-competitive inhibition

(2) a - enzyme with an allosteric modulator added

     b - normal enzyme activity

     c - competitive inhibition

(3) a - enzyme with an allosteric stimulator

     b - competitive inhibition added

     c - normal enzyme reaction

(4) a - normal enzyme reaction

     b - non-competitive inhibitor added

     c - allosteric inhibitor added

Which of the following contain $\mathrm{\beta }$-1, 4 linkage?

(1) Maltose

(2) Sucrose

(3) Lactose

(4) Fructose

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

(1) enhance oxidative metabolism

(2) are conjugated proteins

(3) arc exclusively synthesised in the body of a living organism as at present

(4) help in regulating metabolism.