Q1 · 2000-2022 · 2 marks
\beta-D-Glucose is represented as
- (a)
- (b)
- (c)
- (d)
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Answer: (a)
GATE Chemistry (CY) — Natural Products previous year questions
18 questions · 2000 · all with verified answer · last checked 2026-11-10
Q2 · 2000-2022 · 2 marks
Which one of the following compunds will form as osazone derivative?
- (a) \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COCH}_{2} \mathrm{OH}
- (b) \mathrm{CH}_{3} \mathrm{COCH}_{2} \mathrm{CH}_{2} \mathrm{OH}
- (c) \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CHOHCH}_{2} \mathrm{OH}
- (d) \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COCH}_{2} \mathrm{OCH}_{3}
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Answer: (a)
Q3 · 2000-2022 · 2 marks
Proteins are biopolymers. The monomer units present in them are
- (a) carbohydrates
- (b) amino acids
- (c) fatty acids
- (d) alkenes
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Answer: (b)
Q4 · 2000-2022 · 2 marks
For the aldotetroses I-IV, the combination of TRUE statements, among P - T, is: 
I II III IV P = I and II are diastereomers and II and III are enantiomers. Q=I and IV are mesomers and are optically inactive. R = I and III can be interconverted by a base catalysed isomerisation. \mathrm{S}= only I and IV are \mathrm{HIO}_{4} cleavable. T = I and III are D - sugars and II and IV are L - sugars.
I II III IV P = I and II are diastereomers and II and III are enantiomers. Q=I and IV are mesomers and are optically inactive. R = I and III can be interconverted by a base catalysed isomerisation. \mathrm{S}= only I and IV are \mathrm{HIO}_{4} cleavable. T = I and III are D - sugars and II and IV are L - sugars. - (a) \mathrm{Q}, \mathrm{R}, \mathrm{T}
- (b) P, R, T
- (c) Q, S, T
- (d) P, Q, S
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Answer: (b)
Q5 · 2000-2022 · 2 marks
Three molecular ionic states, \mathrm{P}-\mathrm{R}, are possible for the amino acid histidine. Identify the correct choice of pH values, respectively, for the observation of the ionic states P-R. 
- (a) P at \mathrm{pH} 1: \mathrm{Q} at \mathrm{pH} 12: \mathrm{R} at pH 7
- (b)
P at pH 7 ; Q at pH 1 ; R at pH 12 - (c) P at pH 12; Q at pH 7; R at pH 1
- (d) P at pH 12 ; Q at pH 1 ; R at pH 7 GATE 2005
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Answer: (a)
Q6 · 2000-2022 · 2 marks
The \mathrm{pK_a} values for the three ionizable groups X, Y and Z of glutamic acid are 4.3, 9.7 and 2.2 respectively. The isoelectric point for the amino acid is
- (a) 7.00
- (b)
3.25 - (c) 4.95
- (d) 5.95
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Answer: (b)
Q7 · 2000-2022 · 2 marks
Identify the Correct set of stereochemical relationships amongst the following monosaccharides I-IV 
I II III IV
I II III IV - (a) I and II are anomers; III and IV are epimers
- (b) I and III are epimers; II and IV are anomers
- (c) I and II are epimers; III and IV are anomers
- (d) I and III are anomers; I and II are epimers.
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Answer: (d)
Q8 · 2000-2022 · 2 marks
Treatment of the pentapeptide Gly-Arg-Phe-Ala-Ala, in separate experiments, with the enzymes Trypsin, Chemotrypsin and Carboxypeptidase Arespectively, gives :
- (a) Gly-Arg + Phe-Ala-Ala; Gly-Arg-Phe+Ala-Ala; Gly-Arg-Phe-Ala+Ala
- (b) Gly-Arg-Phe+Ala-Ala; Gly-Arg-Phe+Ala-Ala; Gly-Arg-Phe-Ala+Ala
- (c) Gly-Arg+Phe-Ala-Ala; Gly-Arg-Phe-Ala+Ala; Gly-Arg-Phe+Ala-Ala
- (d) Gly-Arg + Phe-Ala-Ala; Gly-Arg-Phe+Ala-Ala; Gly+ Arg-Phe-Ala + Ala
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Answer: (a)
Q9 · 2000-2022 · 2 marks
Cyanogen bromide (CNBr) specifically hydrolyses the peptide bond formed by the C–side of
- (a) methionine
- (b) glycine
- (c) proline
- (d) serine
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Answer: (a)
Q10 · 2000-2022 · 2 marks
The decreasing order of isoelectric point for the following \alpha-amino acids is Lysine (I), Alanine (II), Glutamic acid (III)
- (a) I > II > III
- (b) II > I > III
- (c) III > I > II
- (d) I > III > II
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Answer: (a)
Q11 · 2000-2022 · 2 marks
The sequence of an mRNA molecule produced from a DNA template strand with the composition 5'–AGCTACACT–3' is
- (a) 5'–AGUGUAGCU–3'
- (b) 5'–UCGAUGUGA–3'
- (c) 5'–AGTGTAGCT–3'
- (d) 5'–TCGATGTGA–3'
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Answer: (c)
Q12 · 2000-2022 · 2 marks
Number of thymine residues in a 5000 kb DNA containing 23% guanine residues is:
- (a) 2.70 \times 10^{6}
- (b) 2.70 \times 10^{7}
- (c) 1.35 \times 10^{6}
- (d) 1.35 \times 10^{7}
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Answer: (c)
Q13 · 2000-2022 · 2 marks
A disaccharide that will not given Benedict's test and will not form osazone is
- (a) maltose
- (b) lactose
- (c) cellobiose
- (d) sucrose
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Answer: (d)
Q14 · 2000-2022 · 2 marks
The correct sequence of the amino acids present in the tripeptide given below is
- (a) Val-Ser-Thr
- (b)
Val - Thr - Ser - (c) Leu - Ser - Thr
- (d) Leu-Thr-Ser GATE 2014
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Answer: (a)
Q15 · 2000-2022 · 2 marks
Amongst the following, the structure of guanosine is
- (a)
- (b)
- (c)
- (d)
GATE 2015
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Answer: (d)
Q16 · 2000-2022 · 2 marks
The compound given below is a (Hirsutene)
- (a) sesterterpene
- (b) monoterpene
- (c)
sesquiterpene - (d) triterpene
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Answer: (c)
Q17 · 2000-2022 · 2 marks
A tetrapeptide, made up of natural amino acids, has alanine as the N-terminal residue which is coupled to a chiral amino acid. Upon complete hydrolysis, the tetrapeptide gives glycine, alanine, phenylalanine and leucine. The number of possible sequences of the tetrapeptide is ____. GATE 2020
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Answer: 4
Q18 · 2000-2022 · 2 marks
Major product formed in the given reaction is: 
- (a)
- (b)
- (c)
- (d)
GATE 2021
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Answer: (a)
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