1

### AIPMT 2001

Which statement is incorrect about peptide bond?
A
C $-$ N bond length in proteins is longer than usual bond length of N $-$ C bond.
B
Spectroscopic analysis shows planar structure of group.
C
C $-$ N bond length in proteins is smaller than usual bond length of C $-$ N bond.
D
None of the above.

## Explanation

Due to resonance C — N bond in protein acquires double bond character and is smaller than usual C — N bond.
2

### AIPMT 2001

Which of the following is correct?
A
Cycloheptane is an aromatic compound.
B
Diastase is an enzyme
C
Acetophenone is an ether.
D
All of these.

## Explanation

Diastase is an enzyme. (The protein produced by living systems which acts as a biological catalyst). Enzymes are characterised by the name ending with -ase.
3

### AIPMT 2001

Which of the following is correct about H-bonding in nucleotide?
A
A $-$ T, G $-$ C
B
A $-$ G, T $-$ C
C
G $-$ T, A $-$ C
D
A $-$ A, T $-$ T

## Explanation

Guanine G is linked to cytosine C by three hydrogen bonds and adenine A is linked with thymine T by two hydrogen bonds. It is abbreviate as : G ≡ C and A = T
4

### AIPMT 2000

Which one is responsible for production of energy in bio-reaction?
A
Thyroxine
B
C
Oestrogen
D
Progesterone

## Explanation

It is a hormone secreted from thyroid gland. It controls various biochemical reactions involving burning of proteins, carbohydrates, fats to release energy.