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Biomolecules · Question 32

AIPMT 2010 (Mains)MCQMedium📈 Topic in 25% papers+4−1
1

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

Answer

(4) enolisation of fructose followed by conversion to aldehyde by base

Solution

Fructose is a ketohexose (keto group at C-2), yet it reduces Tollens' reagent.

∵ In the alkaline medium of the reagent, fructose undergoes enolisation (enediol formation) and rearranges to an aldose (glucose/mannose), i.e. an aldehyde (Lobry de Bruyn–van Ekenstein rearrangement).

⇒ The aldehyde formed reduces [Ag(NH3)2]+ to silver.

Answer: (4)

AIPMT 2010 (Mains)

Keep practising — Biomolecules

2

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

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

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
4

Which of the following hormones contains iodine?

  1. Testosterone
  2. Adrenaline
  3. Thyroxine
  4. Insulin
AIPMT 2009
5

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
6

Which of the following is an amine hormone?

  1. Insulin
  2. Progesterone
  3. Thyroxine
  4. Oxypurine
AIPMT 2008
7

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
8

Which of the following vitamins is water-soluble?

  1. Vitamin E
  2. Vitamin K
  3. Vitamin A
  4. Vitamin B
AIPMT 2007
9

The human body does not produce

  1. enzymes
  2. DNA
  3. vitamins
  4. hormones
AIPMT 2006
10

Which one of the following is a peptide hormone?

  1. Adrenaline
  2. Glucagon
  3. Testosterone
  4. Thyroxine
AIPMT 2006
11

During the process of digestion, the proteins present in food materials are hydrolysed to amino acids. The two enzymes involved in the process Proteins enzyme (A) Polypeptide enzyme (B) Amino acids are respectively

  1. invertase and zymase
  2. amylase and maltase
  3. diastase and lipase
  4. pepsin and trypsin
AIPMT 2006

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