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Biomolecules

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

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)

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Ques. 2AIPMT 2010 (Prelims)

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

  1. (+) Sucrose
  2. (+) Lactose
  3. (+) Maltose
  4. (−) Fructose
Ques. 3AIPMT 2009

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
Ques. 4AIPMT 2009

Which of the following hormones contains iodine?

  1. Testosterone
  2. Adrenaline
  3. Thyroxine
  4. Insulin
Ques. 5AIPMT 2008

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.
Ques. 6AIPMT 2008

Which of the following is an amine hormone?

  1. Insulin
  2. Progesterone
  3. Thyroxine
  4. Oxypurine
Ques. 7AIPMT 2007

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
Ques. 8AIPMT 2007

Which of the following vitamins is water-soluble?

  1. Vitamin E
  2. Vitamin K
  3. Vitamin A
  4. Vitamin B
Ques. 9AIPMT 2006

The human body does not produce

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

Which one of the following is a peptide hormone?

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

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

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