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Biomolecules · Question 31

AIPMT 2011 (Prelims)MCQMedium📈 Topic in 0% papers+4−1
1

Which one of the following statements is not true regarding (+) lactose?

  1. On hydrolysis (+) lactose gives equal amount of D(+) glucose and D(+) galactose.
  2. (+) Lactose is a -glucoside formed by the union of a molecule of D(+) glucose and a molecule of D(+) galactose.
  3. (+) Lactose is a reducing sugar and does not exhibit mutarotation.
  4. (+) Lactose, C12H22O11 contains 8 –OH groups

Answer

(3) (+) Lactose is a reducing sugar and does not exhibit mutarotation.

Solution

As per NCERT, lactose (milk sugar) is composed of β-D-galactose and β-D-glucose; the linkage is between C1 of galactose and C4 of glucose.

(1) Hydrolysis gives one molecule each of D(+)-glucose and D(+)-galactose: true.

(2) It is formed by the union of glucose and galactose through a β-glycosidic linkage: true as stated.

(3) The glucose unit has a free hemiacetal –OH at C1, so lactose is a reducing sugar and it also shows mutarotation the statement 'does not exhibit mutarotation' is not true.

(4) Lactose has 8 free –OH groups (4 in the galactose unit + 4 in the glucose unit): true.

Answer: (3)

AIPMT 2011 (Prelims)

Keep practising — Biomolecules

2

Fructose reduces Tollens' reagent due to

  1. asymmetric carbons
  2. primary alcoholic group
  3. secondary alcoholic group
  4. enolisation of fructose followed by conversion to aldehyde by base
AIPMT 2010 (Mains)
3

Which one of the following does not exhibit the phenomenon of mutarotation?

  1. (+) Sucrose
  2. (+) Lactose
  3. (+) Maltose
  4. (−) Fructose
AIPMT 2010 (Prelims)
4

The segment of DNA which acts as the instructional manual for the synthesis of the protein is

  1. ribose
  2. gene
  3. nucleoside
  4. nucleotide
AIPMT 2009
5

Which of the following hormones contains iodine?

  1. Testosterone
  2. Adrenaline
  3. Thyroxine
  4. Insulin
AIPMT 2009
6

In DNA, the complementary bases are

  1. adenine and guanine; thymine and cytosine
  2. uracil and adenine; cytosine and guanine
  3. adenine and thymine; guanine and cytosine
  4. adenine and thymine; guanine and uracil.
AIPMT 2008
7

Which of the following is an amine hormone?

  1. Insulin
  2. Progesterone
  3. Thyroxine
  4. Oxypurine
AIPMT 2008
8

RNA and DNA are chiral molecules, their chirality is due to

  1. chiral bases
  2. chiral phosphate ester units
  3. D-sugar component
  4. L-sugar component
AIPMT 2007
9

Which of the following vitamins is water-soluble?

  1. Vitamin E
  2. Vitamin K
  3. Vitamin A
  4. Vitamin B
AIPMT 2007
10

The human body does not produce

  1. enzymes
  2. DNA
  3. vitamins
  4. hormones
AIPMT 2006
11

Which one of the following is a peptide hormone?

  1. Adrenaline
  2. Glucagon
  3. Testosterone
  4. Thyroxine
AIPMT 2006

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