1
MCQ (Single Correct Answer)

AIPMT 2011 Mains

Which of the statements about ''Denaturation'' given below are correct?

(1)  Denaturation of proteins causes loss of secondary and tertiary structures of the protein.
(2)  Denaturation leads to the conversion of double strand of DND into single strand.
(3)  Denaturation affects primary structure which gets distorted.
A
(2) and (3)
B
(1) and (3)
C
(1) and (2)
D
(1), (2) and (3)

Explanation

When the proteins are subjected to the action of heat, mineral acids or alkali, the water soluble form of globular protein changes to water insoluble fibrous protein. This is called denaturation of proteins. During denaturation secondary and tertiary structures of protein destroyed but primary structures remains intact.
2
MCQ (Single Correct Answer)

AIPMT 2011 Prelims

Which one of the following statements is not true regarding (+) lactose?
A
On hydrolysis (+) lactose gives equal amount of D(+) glucose and D(+) galactose.
B
(+) Lactose is a $$\beta $$-glucoside formed by the union of a molecule of D(+) glucose and a molecule of D(+) galactose.
C
(+) Lactose is a reducing sugar and does not exihibit mutarotation.
D
(+) Lactose, C12H22O11 contains 8-OH groups

Explanation

(+) Lactose is a reducing sugar and all reducing sugar shows mutarotation.
3
MCQ (Single Correct Answer)

AIPMT 2011 Mains

Which of the following is not a fat soluble vitamin?
A
Vitamin B complex
B
Vitamin D
C
Vitamin E
D
Vitamin A

Explanation

Vitamin B complex is not a fat soluble vitamin. It is a water soluble vitamin.
4
MCQ (Single Correct Answer)

AIPMT 2010 Mains

Fructose reduces Tollen's reagent due to
A
asymmetric carbons
B
primary alcoholic group
C
secondary alcoholic group
D
enolisation of fructose followed by conversion to aldehyde by base

Explanation

Under alkaline conditions of the reagent, fructose gets converted into a mixture of glucose and mannose (Lobry de Bruyn van Ekenstein rearrangement) both of which contain the –CHO group and hence reduce Tollens’ reagent to give silver mirror test.

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