10 Biomolecules

SOME SOLVED EXAMPLES

1. Convert glucose to fructose and fructose to glucose.
Sol. Conversion of glucose to fructose.
H~c=0
H-C-OH
Hc=N-NH-Ph
|
C=N-NH-Ph
HO-C-H 3Ph--NH-NH, HO-C-H H®H,O
H-C-OH H-C-OH
H--OH H- -OH
CH,OH CH,OH

H
ÇH,OH
C=0 C=0
HO-C-H Zn + CH3COOH HO-C-H
H-C-OH H-C-OH
H- -OH H- -OH
CH,OH CH,OH
" Conversion of fructose to glucose.

CH-OH
C=0
Hc-OH C-OH
H~c=0
HoH
HO-H OH/H,0 HO -H OHH,0 HO -H
H -OH H OH H OH
H -OH H OH H -OH

CH,OH CH,0H CH,OH

Fructose Enol of fructose Glucose
 10,2 GRB Advanced Problems in Organic Chemistry tor JEE
D-arabinose.
2. Convert D-erythrose to D-ribose and C=N
CH=NH
H -OH
Hz, Pd-BaSO4
H OH
H -OH H -OH
H -OH H
-OH
CH,OH CH,OH
H
C=0
H OH
H\(=0
H -OH HCN
H OH
Sol.
H -OH
H-OH
CH,OH
CH,OH D-ribose

C=N CH=NH
HO -H
Hz, Pd-BaSO4
HOH
H -OH H- -OH
H -OH H+OH
CH,0H CH,OH

H~c=0
HO-H
H-OH
H -OH
CH,OH
D-arabinose

3. Convert D-glucose to D-arabinose.

HO. Çoo(Ca*21/2
Hc=O
H-OH H-oH
C=0
H -OH
-H
HO H Brz, H,0 HO H Ca(OH)2 HO
Sol. H OH H OH H -OH
H-OH H OH H -OH
CH,OH CH,OH CH,OH
D-glucose

H,0, Fe*3
H~c=0
HO -H
+ CO)
H -OH
H -OH
CH,OH
D-arabinose
Biomolecules 10.3

4. Find out final product of reactions.

CH,0Ho. CH;1 (Excess) H®H,O
(a) HO OH X Y
Ag,0
HO OH
CH,OH.
(b) HO OCH3 2HI04 P
H®H,0 R
HO OH S
CH,OH 0. CH;I (Excess)
Sol. (a) HÌ OH
Ag,0
HO OH

H,Co
CH,0CH30 oCH,
H
-CH,OH
H,C0 OCH,
X

H,CO
CH,0CH3o
H,CO OCH3

CH,0CH Þ CH,0CH30.
H;C0 H,0 HC OH
-H
OCH; H,C0 OCH3
H3C0
(Stable)
óCH,OHO. 2HIO4
(b) HO 5 OCH3
HO OH 1

H
CH,OHo, HOH,0 H=0
5 H oCHs HOH
1
CH,OH
6

R
+ +

HO-CH H
HCOOH
 JEE them.green theycarbon
polyhydroxy
for in sugar
to synthesised terminal
Chemistry CH,-CH--ð CH,-ÇH--ß hydrolysed simple
are ÇH,-OHH-OHCH-OH H,-OH
CH-OH Ketohexose
=12
starches either AldoseKetose
GNH; :NH, (=0
Advanced
GRB
Organic
pH are or
at
and be They monosaccharide
group ’ ’
in =8 CH,-CH-COOH NH ;NH
:N andcan C C,at
Problems
pH sugars
energy. carbonylatCarbonyl
Carbonyl CH-OH
CH-OH
CH-OH
Hc0
CH,-OH
CH-OHAldohexOse
pH=4,:NH, pH=4 12pH= that
chemical
=0, AN-H
(Histidine)
CH,-CH-Þ-OHCH,-ÇH--ß
as compounds
to with
called
referred chain
of photosynthesis. ÇH,-OHCH,-OH
pH C's
are ).
at
Histidine GNH3 houses the(C other (=0 Ketotriose
NH3 or
commonly carbohydrates
it
to
carbonCC=0
ketones in all
store atom on
of NH NH areby carbon
-OH CH,-OH
CH-OH
structure algae adjacent
Carbohydrates, Aldotriose
=0
pH pH=8 andCarbohydrates
Carbohydrates simplest
HN, CHO
and 3-7
aldehyde C4
Draw or
plantThecontain
(C;)
10.4 5. Sol. 1. 2.
10.5 thecenter CH,OH are caneither as position
C=0 -OHOH CH,OH point. five
known
on -H D-Fructose only group a
chiral
carbonyl havingwhile
center melting
carbonyl the
the HO H H
OH OH CH,OH ring center
hemiketal
anomers.
in
chiral CHO -HH D-Galactose differ
theon high pyranose OH-o
group -OH CH,OH chiral H
from projection.
CHO-H -H-H other.
L-Glucose and
having that
called
one H HO-OH
HOH C-4,
Epimer by
or
groups ring.
a monosaccharides
OH
farthest eacharound hemiacetal
a form
anomers
Two
form
cyclisation
HO H HOHO -OH OH CH,OH soluble called are carbon.
furanose
of CHO H D-Glucose hydroxy hemiketal
theFischer
center enantiomers
configuration compound +
OH
CH,OH water is hemiketal
has -OH
-OH form O-atom H
a
CHO-OH D-Glucose H HO H H called
L-sugar
chiral
H
several
taste, or cyclic
in to
left -OH-OHCH,OH cyclisation hemiacetal
an is carbonyl
are CHO-H-H D-Mannose or
theon the H HO H H in in containing containing
O-atom a hemiacetal
C-2
differ
C-2,
Epimer, sweet of
on while
on CH-OH compounds differ
of stereoisomers
ring.
an hydroxyl
group carbonyl HOHO H H
-OH configuration cyclic
are intramolecular -OH
H
project CHO HO-C-HL-Sugar that theringcontaining
OH -OH OH CH,OH monosaccharides
monosaccharide the
| diastereomers
CHO -H D-Glucose in Two
farthest
from same membered at
the
Fischer centre atom of
called
epimers. are group
BiomolD-sugar
ecules
has from
a
Chiral
C=0
CH,-OH
H-C-OH
of
L- H HOH H
in
six ring
undergo
carbon.
Cyclisation
Anomers
-OH
in farthest and or six nembered
right CHO
D-Sugar Two All All five anomeric
A D- A the
1, 4. 5. 6.
Ol
10.6 GRB Advanced Problems in Organic Chemistry for JEE

Cyclic structure of Glucose :

Hc
HO
Hc=0H
H -OH
H HO
H OH
H
H~c=OH
H
HO-
OH
H
H -OH H QH) H -OH
H H -OH H
CH,OH CH,OH CH,OH
B-D-Glucose D-Glucose a-D-Glucose
(62.9%) (0.1%) (37%)

CH,OH CH,OH
H
-0
H OH H
H a-D-Glucose and H
OH H B-D-Glucose are OH H
OHN H anomer OH OH

H OH H OH
B-D-Glucose C-D-Glucose

Cyclic structure of Fructose :

CH,-OH
HO 1 HOCH,OHOH
CH,OH
HO -H HO -H H
H -OH H+0H) H -OH
H H -OH H

CH,OH CH,OH CH,OH

D-Fructose a-D-Fructose
B-D-Fructose

CH,OH OH CH,OH CH,OH

H HO H HO
H CH,OH H OH
a-D-Fructose OH H
OH H
and
B-D-Fructose are anomer
Carbohydrates that can be oxidised with Tollen's, Benedict or Fehling reagent are
called reducing sugar while those who donot react with these reagents are called nou
reducing sugars. GIlucose and fructose are reducing sugar.
Each cyclic hemiacetalof glucose can be isolated and crystallised seperately, bu
when any one compound is placed in solution an equilibrium mixture of all three tou
results. This process is called mutarotation.
Biomolecules 10.7

Reactions of Glucose :
5HCOOH CN

HCHO H-C-OH
COOH
(ÇH-OH), (ÇHOH)4
SHIO4
CH,OH
HCN CH,OH
Gluconic acid Br2, H,O Glucocyanohydrin

COOH Hc=0 CH-OH H,N-OH

H\cN-OH
(ÇH-OH)4 Tollen's Reagent (ÇH-OH)4
CH-OH or CH-OH CH,OH
Fehling solution CH-OH (Glucose oxime)
Gluconic acid
HNO3 NaBH4
CH-OH
COOH CH,-OH
(ÇH-OH)4 CH-OH (ÇHOH)4
Glucose
Red P + HÊ
COOH SCH,COOH CH,OH
Saccharic acid Sorbitol
3Ph--NH-NH,

n-Hexane
C=N-NH-Ph
(ÇH-0--CH;)4
Ç=N-NH-Ph
CH;-0---CH;
(ÇH-OH)3
CH-OH
Glucosazone
Disaccharides
1. Maltose :
-H,0
CoH1;06 + CoHj2O6
a-D-Glucose a-D-Glucose Maltose

CH,OH CH,OH
H H H H
H H
OH H OH H
OH OH

H OH H OH
a-1,4-Glycosidic
linkage
It is reducing sugar.
10.8 GRB Advanced Problems in Organic Chemistry for JEE

2. Sucrose :
CçHË;06 + CçH0%
a-D-Glucose B-D-Fructose Sucrose

CH,OH
H H HO-CH,. H
H
OH H H HÌ
OH CH,OH
H OH OH H
o-1,8-2-G1ycosidic
linkage
It isnon-reducing sugar.
3. Lactose :

C7H06 + CçH1206 ’ CiH2O11

B-D-Galactose B-D-Glucose Lactose

CH;OH CH,OH
HÌ H
-0 H
H H
OH H OH H
H H OH

H OH H OH
(B-1,4-Glycosidic linkage)
It is reducing sugar.

EXERCISE-1 ONLY ONE CORRECT ANSWER

1. The minimum number of carbon atoms that should be present in a carbohydrate is :

(a) 2 (b) 3
(c) 4 (d) 6
2. Carbohydrates are commonly defined as :
(a) Polycarbonyl compounds (b) Polycarboxylic acid
(c) Polyhydroxy carboxylic acid (d) Polyhydroxy aldehyde and ketone
3. Carbohydrate that on attempt hydrolysis are not cleaved to smaller carbohydrates
are called:
(a) Monosaccharide (b) Oligosaccharide
(c) Polysaccharide (d) Disaccharide
4. The number of chiral centers in the open chain structure of glucose is :
(a) 3 (b) 4
(c) 5 (d) 6
Biomolecules 10.9

5. Cane sugar on hydrolysis gives:

(a) Glucose and Galactose (b) Glucose only
(c) Glucose and Fructose (d) Fructose only
6. The carbohydrate present in milk :
(a) Sucrose (b) Maltose (c) Lactose (d) Cellobiose
7. Which of the following structures represents
OH
O-D-glucopyranose?
OH OH OH

-oOH
(a) OH (b) (ÌH (c) (d) HÌ
N
HO ÖH HÎ HÎ OH HÓ OH
OH ÔH OHOH OH
8. a-D-Glucopyranose and B-D-Glucopyranose are :
(a) Anomers (b) Epimer
(c) Diastereomers (d) Meso compounds
9. The disaccharide that is constituted of two
glucose unit is :
(a) Lactose (b) Maltose (c) Sucrose (d) Ribose
10. Invert sugar is an equimolar mixture of:
(a) D-GIucose and D-Fructose (b) D-Glucose and L-Fructose
(c) D-GIucose and L-Glucose (d) D-Fructose and L-Fructose
11. In &-D-Glucose, the anomeric carbon is at :
OH

HO}7OH
ÖH
(a) 1 (b) 2 (c) 4 (d) 5
12. In the ring structure of fructose, the anomeric carbon is :
(a) C1 (b) C5 (c) C2 (d) C-6
13. Fructose reduces Fehling's solution due to the
presence of :
(a) hydroxy group (b) aldehyde group
(c) ketone group (d) a-hydroxy ketone group
Which of the following reagents may be used to identify glucose?
(a) Neutral FeCl; solution (b) Ammoniacal AgNO3 solution
(c) CHCl, and KOH (alc.) (d) NaHSO3
15. Upon hydrolysis lactose breaks down into :
(a) glucose and mannose (b) glucose and fructose
(c) glucose and galactose (d) glucose and arabinose
l6. Glucose and galactose differ in configuration at :
(a) C1 (b) C-2 (c) C-3 (d) C-4
10.10 GRB Advanced Problems in Organic Chemistry for JEE

17. Which of the following is C-2 epimer of D-GIucose?

(a) D-Galactose (b) L-Glucose (c) D-Mannose (d) D-Fructose
18. Starch is apolymer of :
(a) fructose (b) glucose (c) lactose (d) ribose
19. Glucose when treated with CH30H in presence of dry HCI gives - and
B-methylglucosides because it contains :
(a) an aldehydic group (b) CH,-OHgroup
(c) Five -OH group (d) None of these
20. Which of the following is a non reducing sugar?
(a) Glyceraldehyde (b) Glucose
(c) Fructose (d) Sucrose
21. Glycosidic linkage is :
(a) an amide linkage (b) an ester linkage
(c) an ether linkage (d) an amine linkage
22. Pyranose ring consist of askeleton of:
(a) 5 carbon atoms and one oxygen atom
(b) 6 carbon atoms
(c) 6 carbon atoms and one oxygen atom
(d) 4 carbon atoms and one oxygen atom
23. Glucose and Fructose can be differentiated by:
(a) Tollen's reagent (b) Cold KMnO4
(c) Br,/H,0 (d) PCC
24. Periodic acid splits glucose and fructose into formic acid and formaldehyde. Ratio
of formic acid and formaldehyde from glucose and fructose is :
(a) 5/1 and 4/2 (b) 5/1and 3/2
(c) 4/2 and 4/2 (d) 3/2 and 4/2
25. An aldose is converted into its next higher homologue by :
(a) Ruffs method (b) Amadori rearrangement
(c) Kiliani synthesis (d) Wohl's method
26. The change in optical rotation with time of freshly prepared solution of sugar is
known as :
(a) Specific rotation (b) Mutarotation
(c) Inversion (d) Rotatory motion
27. Which of the following gives an optically inactive aldaric acid on oxidation with
dilute HNO, acid?
CHO CHO CHO CHO
H- -OH H -OH H -OH (d) HO-H
(a) H- -OH (b) HO -H (c) HO H H -OH
HO -H H -OH HO- -H H -OH
CH,OH H,OH H,OH CH,OH
28. Glucose does not react with:
(a) CçHsNHNH, (b) H,N-OH (c) HCN (d) NaHSO3
Biomolecules
10.11
0 Cellulose is a linear polymer of :
(a) a-D-Glucose (b) B-DGlucose (c)
30. Rapid interconversion ofa-D-Glucose and a-D-Fructose
(d) B-LGlucose
(a) racenmisation B-D-Glucose solution is known as :
in
(c) fluxional isomerisation (b) asymmetric induction
(d) mutarotation
a1. Which of the following
represents the anomer of compound shown?
HOCH, H

H
OH
OH OH
HOÇH,0 H
HOÇH, OH
(a) HOH H
OH (b) H
H H,
H
H OH
OH OH
H
OH
(c)
HOCHH OH (d) Allof these
H H
HC-0H
COH
HO -H
32. the given is enol form of :
H -OH
H -OH
CH,OH
(a) D-Gucose (b) D-Mannose (c) D-Fructose (d) All of these
33. The numbers of chiral centers present in glucopyranose and
fructofuranose are :
(a) 4 and 3 (b) 5 and 4 (c) 4 in each (d) 5 in each
34. Which of the following is an amino acid?
(a) H,N-COOH (b) CH3 CH-C0OH
CONH,

(c) NH,-C-COOH (d)

COOH

H
35. Amino acids undergo internal acid base reaction to form :
(a) an amide (b) a lactum (c) zwitter ion (d) a peptide
10.12 GRB Advanced Problems in Organic Chemistry for JEE
lowest solubility in water :
36. An amino acid usually shows its
(a) in acidic solution
(b) in basic solution
(c) at pH7 (d) at isoelectric point
peptide linkage?
37. Which one among following is a
-C-NH (b) -N=C-0
(a)
R

(c) -C=N H (d) -C-0-N

R H H

38. Consider the following sequence of reaction,

1. BrCH, (COOEt)2, 1. Ph-CH, -Br

NK 2. C, H,0Na
A
2. HCI, H,0, A
B

The major final product (B) is :

(a) H,N-CH,-COOH (b) Ph-CHCOOH
NH,
NH, COOEt
(c) PhCH,-CH CO0H (a) PhCH COOH

NH,
39. Which of the following is the major solute species in a solution of lysine at
pH=10.5?
ÇOOH COOH COo
-H (C) H,N -H (d) H,N -H
(a) HN -H (6) H,N
(CH))4 (CH,)4 (CH,)4 (CH,)4
GNH, NH, NH; NH,

40. Which of thefollowing is the major solute species in asolution of glutamic acid at
pH=1.3?
ÇOOH ÇOO COO Çoo
(a) H,N H (6) H,N -H
-H (C) H,N -H (d) H,N
(CH-) (CH)2 (CH,)2
(CH,)2 Cooe
COOH COOH COOH
Biomolecules 10.13

41. Which
(a)
ofpHthe following statements most correctly defines the isoelectric point?
The at which all molecular species are ionised and that carry the same
charge.
(b) The pH at which all molecular species are neutral and
uncharge.
(c) The pH at which half of the molecular species are ionised and the other half
unionised.
(d) The pH at which negatively and positively charged molecular species are
present in equal concentration.
42, Alanine at its isoelectric point, exist in solution as :

(a) H,N-ÇH-CO0 (b) H3NÇH-COOH

CH3 CH,
(c) H;N-ÇH-CO0 (d) H,N ÇH-COOH
CH,
CH,
43. )H,N NH3 (2)
COOH
()
The order of decreasing acidity of these acidic sites is :
(a) x> z> y (b) z>x> y
(c) x> y>z (d) y>x>z
44. Biuret test is used for the detection of :
(a) sugar (b) proteins (c) fats (d) starch
45. 0-Amino acids behave as crystalline ionic solid and have high melting point due
to the presence of:
(a) -NH2 group (b) -COOHgroup
(c) both-NH, and -COOH (d) None of these
46. Which of the following is correct structure of histidine at pH = 0?
EH3 NH3
CH;-CH-COOH CH-CH-COO
(a) H N NH (b) H N NH
NH3
CH-CH-COO CH-CH-COO
(c) N NH (a) N NH2
10.14 GRB Advanced Problems in Organic Chemistry for JEF
CHO

H-OH KCN H, H}0 ’ Product.

47.
CH-OH HCI Pd-BaSO4

CH,-OH
Find out final product:
CH,OH CHO

(a) (CHOH)3 (b) (ÇH-OH)3

CH,OH CH,-0H
COOH COOH

(c) (ÇH-OH)3 (d) (ÇHOH);

CH,-0H COOH
CHO
Br,, H,0 H,0,
48. (ÇHOH)3 Fe3+
’ Product:
Ca(OH),
CH,OH
COOH CHO CHO COOH

(a) (ÇHOH)3 (b) (ÇHOH)4 (c) (ÇHO)2 (d) (ÇHOH);

CH,OH CH,OH CH,OH COOH

HË0, A
49.
(O-c -C-H + NH, + HCN

OH
H,0
Product:

OH

(a) Ph-CH,-C H (b) Ph--CH,-C-H

NH, CN
H

(c) Ph--CH, CNH3 (d) All of these

COO
Biomolecules 10.15

EO, Find out the structure of lactose :

OH OH

OH OH OH
OH
OH OH
HO
VOH OH
(a) (b)
OH N
HO
OH
ÖH OH
OH OH

(c) /OH OH (d) None of these

HO
ÖH OH
51. A tripeptide is written as Glycine-Alanine-Glycine. The correct structure of
tripeptide.
CH3 CH3
(a) NH NH/
OH
(b) NH OH
H,N H,N NH
CH,

(c) NH OH
NH (d) None of these
H,N
CH3
52. What would be the net charge on the given amino acid at pH=14?
COOH

H,N-CH-(CH,)4-C-OH
(a) -1 (b) -2
(c) +1 (d) +2
O3. How many moles of HIO4 is required to break down the given molecule here ?

CH 0CH3
H OH
H -OH
H
CH,OH
(a) 0 (b) 1
(c) 2 (d) 3
10.16 GRB Advanced Problems in Organic
Chemistry for JEE
54. The products of HIO4 oxidation of the following compound is :
OH
OCH,
OH
OH

OH

OCH; 0CH;
(a)H
+ HCOOH + HCHO

HH H

OCH; OCH3
H HÌ
(c) + HCH0 (d) + HCOOH

Þ OH OH HH
55. Which of the following compounds is D-aldopentose?
OH H OH OH OH

(a) (b) -II

H OH HO OH
H OHH H H
H OH H H H
H
(c) (d)
OH HO" OH
OH H OH OH OH

EXERCISE-2 MORE THAN ONE CORRECT ANSWERS

1. The final product of which of the following reactions furnishes evidence that
glucose has unbranched carbon chain:
1. Br, H,0 1. NaBH4
(a) Glucose (b) Glucose 2. Red P+ HI
2. Red P+ HI

1. HCN CH, OH, H

(c) Glucose. (d) Glucose
2. HÝO
3. Red P+ HI

2. Which of the following reagents would convert an aldose into corresponding

aldonic acid?
(a) Tollen's reagent (b) Fehling's solution
(c) Bromine water (d) RedP+ HI
Biomolecules 10.17

. which of the following statements are correct?

(a) Monosaccharides are optically active polyhydroxy carbonyl compounds.
(b) Fructose does not react with Fehling's solution because it is keto.
ic) a-D-Glucose and B-D-Glucose are anomers.
iA) D-Glucose and D-Mannose are epimers.
AWhich of the following statements are correct?
(a) Hydrolysis of sucrose with dilute acid yields an equimolar mixture of
D-Glucose and D-Fructose.
(b) Acidic hydrolysis of sucrose is accompanied by a change in optical reaction.
(c) In sucrose, the glycosidic linkage is between Clglucose and C2 of fructose.
(d) Aqueous solution of sucrose exhibits mutarotation.
5, Find the corect statements regarding the methyl glucosides obtained by the
reaction of D-Glucose with methanol in presence of dry HCl gas.
(a) These are methyl ether of hemiacetal of glucose formed by intramolecular
reaction.
(b) These are enantiomers.
(c) These are anomers.
(d) In one of these all the substituents are equatorial.
6. Following are the structure of D-Glucose and D-Galactose.
ÇHO CHO
HOH H -OH
HO-H HO H
HOH HO- -H
HoH H -OH
CH,OH CH,OH
D-Glucose D-Galactose
Which of the following statements are correct about these compounds?
(a) They are diastereomers (b) Both are comnponent of lactose
(c) They are C-4 epimer (d) Both are optically active
7. When fructose treated with Tollen's reagent, silver mirror is formed due to
reduction of Ag by:
(a) fructose itself
(b) glucose formed by isomerisation
(C) mannose formed by isomerisation
(d) galactose formed by isomerisation
8. Which of the following do not undergo hydrolysis?
(a) Glucose (b) Fructose (c) Cane sugar (d) Maltose
Y, Which of the following carbohydrate will give the same osazone?
(a) Glucose (b) Fructose (c) Cane sugar (d) Lactose
10, Which of the following are disaccharides?
(a) Glucose (b) Cane sugar (c) Maltose (d) Starch
10.18 GRB Advanced Problems in Organic Chemistry for JEE

11. On hydrolysis which of the following carbohydrate give only glucose?

(a) Sucrose (b) Lactose
(c) Maltose (d) Starch
12. The presence of-CHO group in glucose is confirmed by its :
(a) reaction with PCls
(b) reaction by NaHg to give S-orbitol
(c) reaction with Fehling solution
(d) reaction with Tollen's reagent
13. Which of the following statements are correct for glucose?
(a) It gives positive test with Schiff's reagent
(b) It reacts with NaHSO; and NH3
(c) Pentaacetate derivative of glucose does not react with H, N-OH
(d) It gives positive test with Fehling solution.
14. When D-Glucose is treated with base it is converted into :
(a) D-Fructose (b) D-Mannose
(c) D-Galactose (d) D-Arabinose
15. The phenomenon of mutarotation is shown by :
(a) glucose (b) fructose
(c) cellulose (d) starch
16. Which of the following statements are correct with reference to amino acid?
(a) A carboxylic acid that contains an amino group.
(b) Amino acids are the building blocks of peptides and proteins.
(c) An amino acid may exist as a zwitter ion under suitable conditions.
(d) Aminoacids are negatively charged in basic medium.
17. Which of the following statements are correct with reference to isoelectric point?
(a) It is the point at which amino acids bear no net charge.
(b) Itcorresponds to the pH at which concentration of zwitter ion is maximum.
(c) At isoelectric point amino acid exists as a base.
(d) None of the above.
18. Choose the neutral amino acid:
ÇOOH ÇOOH
(a) H,N -H
(6) H,N -H
CH,-CH-CO0H
OH
ÇOOH ÇOOH
(c) H,NH (d) H,N H

CH CH,-Ph

H
Biomolecules 10.19

19. Consider the following statements about amino acids :

(a) the amino acids that constitute proteins are all L-amino acids.
among the 20 amino acids that constitute proteins, glycine is the only one that
does not possess chiral center.
(c) an important and sensitive test for the detection of L-amino acid is the
ninhydrin colour test.
(d) HNO, liberates nitrous oxide from amino acid.
20. Globular protein is present in :
(a) blood (b) milk
(c) eggs (d) cellulose
21, Which of the following carbohydrates are D-isomers?
OH
CHO
OMe
(a) OH (b) H -OH
Hâ
OH H,OH
COOH
CH,-0Me
HO -H Me0'
(c) (d) OH
H -OH Meo
OMé
COOH
22. Which of the following are reducing sugar?
OH OH

OH
(a) OH HÌ
Hâ
OH OH
OH

OH
OH
ÒH
(b) OH OH
Hâ
OH

(c)
HO
(CHOH)3, OH
10.20 GRB Advanced Problems in Organic Chemistry for JEE
OH OH

-0

OH OH
(d)
HÞ ÖH
OH OH
23. Which are true ?
(a) Glucose is a disaccharide
(b) Starch is a polysaccharide
(c) Glucose and fructose are not anomer
(d) Invert sugar consist of glucose and fructose

EXERCISE-3 LINKED COMPREHENSION TYPE

PASSAGE-1

The isoelectric point (p) of an amino acid is the pH of which it has no net charge.
The plof an amino acid that does not have an ionizable side chain such as alanine, is
midway between its two pk, values.
pK =2.34
CH;-CH -OH

pk =9.69
2.34 +9.69
pl=. =6.02
2
If an amino acid has ionizable side chain, its pl is the average of the pk, values of
the similarly ionizing groups.
1. Find the pl of the following amino acids :

HO CCH, CH CH C OH pk,= 2.19

GNH;K
pKg =4.25 pK, =9.67
(a) 3.22 (b) 6.44
(c) 7.96 (d) 5.93
2. Find the structure of the following amino acids at pH=1:
NH,
OH
H,N
Biomolecules 10.21

NH, NH,
OH
(a) H,N (b) H,N

NH, NH,
OH
(c) H;N (d) H,N
1. What is the pl of the following amino acids?
pK, = 8.95NH,
OH4-pkg -2.18
pk, = 10.79>H,N

(a) 3.22 (b) 9.87

(c) 5.6 (d) 6.49
PASSAGE-2

Study the Observation

Compounds Red P+ HI Ac-O/pyridine Br,+H0 HIO4
Ph-NH-NH,
(X)CçHoos Isopentane Tetraacetate CsHjo6 4 mole No Osazone
()C,Hjo04 Isopentane Triacetate C"HËo0s 1mole Osazone formed
(2)C&Hyo04 n-pentane Triacetate CçHËo0s 2 mole Osazone formed
4. CompoundX' is:
CH-0H CHO

=0 CH OH
|
(a) CH CH, 0H (b) HOC-CH, OH
CH, OH CH, OH
CHO
CH,OH
(c) HO-C CH,OH (d) H-C-CH,OH
CH-0H CH-OH

CH,0H CH,-0H
 10.22 GRB Advanced Problems in Organic Chemistry for JEE

5. Compound Z' is :
CHO CHO CHO
CH,OH
(a) C-0 (b) CH-OH (c) CH, (d) CHOH
CH-OH CH-0H
CH, CH¡
CH-OH CH-OH CH-OH CH-OH
CH,OH CH3 CH,OH CH-0H
6. Which of the following are the reducing sugars?
(a) Xand Y (b) X and Z
(c) Yand Z (d) Allof these
PASSAGE-3

D
(+) Glucose has melting point 146°C and specific rotation [oJ is + 112°C.
Another D
() Glucose has melting point 150°C and specific rotation [a] is +18.7°C.
The two form have significantly different optical rotation but when an aqueous solution
of either form is allowed to stand, its rotation changes. The specific rotation of one form
decreases and rotation of other increases until both solution show the same value
+52.7°.The change in rotation towards an equilibrium value is called mutarotation.
OH CHO OH
H -OH H
Hâ
HÌ -H
HÞ
OH H OH H OH
OH
H -OH
OH
CH,OH 25
(«,=+ 112°
[a]=+18.7°
7. Mutarotation is characteristic feature of:
(a) Epimer (b) Enantiomer
(c) Anomer (d) Ring chain isomer
8. What percentage of B-D-(+) glucopyranose found at equilibrium in the aqueous
solution?
(a) 50% (b) 100% (c) 38% (d) 64%
9. For mannose the mutarotation can be shown in brief asfollow:
OH OH
OH OH
Hâ HÞ
OH
HÞ HÞ
ÖH
(a) a-form (b) B-form (c) open chain (d) none of these
Biomolecules 10.23

PASSAGE-4

Protein are nitrogeneous organic compound having very high molecular mass.
They are polyamide formed from o-anmino acid. The bond formed between two amino
nid is called peptide bond(Ç-NH ), The product obtained by this peptide

bond formation are called peptide and they may be divided as di, tri, tetra, penta
peptide.
10 Consider following statements concerning protein.
1. All amino acids which are constituents of
proteins or a-amino acid.
2. a-amino acids are all optically active and have
3. An especially favourable conformation for the L-configuration.
peptide linkage in protein is
the a-helix arrangement.
4. a-amino acids are connected by ester
linkage.
Which of the following statement are correct?
(a) 1and 3
(b) 1and 2
(c) 2 and 3 (d) 2, 3 and 4
11. The given structure of amino acid will exist at which pH?
COOH

H3N -H

R
(a) 0 (b) 6
(c) 7 (d) 12
12. Which statement are correct about peptide bond?

1. -C-NH- group is planar.

2. C-Nbond length in protein is longer thanusual bond length of C--Nbond.
3. C-Nbond length in proteinis smaller than usual bond length ofC-N bond.
(a) 2 and 3 (b) 1and 2
(c) 2 only (d) 1and 3
10.24 GRB Advanced Problems in Organic Chemistry for JEE

EXERCISE-4 MATRIX MATCHTYPE

1. Column (1) Column (I)

OH

(a) CH-CHCHO P. Carbohydrate

(b) HO Q. Amino acid

OH
NH,
OH
(c) R. Positive Tollen's test

(d) H OH S. Ninhydrin test

2. Column () Column ()
(a) a-D-Glucopyranose: P. Lobry De Bruyn Alberda van
B-D-Glucopyranose Ekenstein transformation
(b) GlucoseMannose . Mutarotation
(c) Fructose Glucose R. Tautomerisation
H, OH
H,

() H- OH -OH S. Epimerisation
HOH
HO -H
H,OH
H,OH
3. Column () Column (|)
(a) Sucrose P. 1,2-glycosidic linkage
(b) Cellulose 2. 1, 4-glycosidic linkage
(c) Maltose R. Polysaccharide
(d) Starch S. Disaccharide
4. Column () Column (I)
(a) Glucose P. Reduces Tollen's reagent
(b) Fructose Q. Exhibit mutarotation in mild alkaline
medium
(c) Mannose R. Produces tetraacetate derivative on
treatment with anhydride and pyridine
(d) Glucopyranoside S. Gets oxidised by Br,, H,0
Biomolecules 10.25

5. Column (1) Column (I)

(a) Maltose P. Invert sugar
(b) Sucrose Q. Reducing sugar
(c) Lactose R. Glycosidic linkage
(d) Fructose S. Disaccharide
6. Column () Column (I)
(a) Cellulose P. Polynmer
(b) Protein Q. Nitrogen containing
(c) Lipid R. Stored food in human
(d) Nucleicacid S. Ester

ANSWERS
Exercise-1 : Only One Correct Answer
1. (b) 2. (d) 3. (a) 4. (b) 5. (c) 6. (c) 7. (a) 8. (a) 9. (b) 10. (a)
11. (a) 12. (c) 13. (d) 14. (b) 15. (c) 16. (d) 17. (c) 18. (b) 19. (a) 20. (d)
21. (c) 22. (a) 23. (c) 24. (b) 25. (c) 26. (c) 27. (b) 28. (d) 29. (b) 30. (d)
31. (b) 32. (d) 33. (b) 34. (d) 35. (c) 36. (d) 37. (a) 38. (c) 39. (d) 40. (a)
41. (d) 42. (c) 43. (c) 44. (b) 45. (c) 46. (a) 47. (b) 48. (c) 49. (c) 50. (a)
51. (c) 52. (b) 53. (b) 54. (b) 55. (a)
Exercise-2: More Than One Correct Answers
1. (a, b, c) 2. (a, b, c) 3. (a, c, d) 4. (a, b, c)5. (a, c, d) 6. (a, b, c, d)
7. (b, c) 8. (a, b) 9. (a, b) 10. (b, c) 11. (C, d) 12. (b, c, d)
13. (C, d) 14. (a, b) 15. (a, b) 16. (a, b, c, d) 17. (a, b) 18. (a, d)
19. (a, b, c) 20. (a, b, c) 21. (a, b, C, d) 22. (b,c,d) 23. (b, c, d)
Exercise-3: Linked Comprehension Type
1. (a) 2. (c) 3. (b) 4. (c) 5. (d) 6. (d) 7. (c) 8. (d) 9. (b) 10. (a)
11. (a) 12. (d)
Exercise-4: Matrix Match Type
1. (a)’ R; (b)’ P,R; (c)’ Q, S; (d)’ P, R
2. (a) ’Q,R; (b) ’ P, S; (c)’P; (d)’ P,R
3. (a) ’P,S; (b) ’ Q,R; (c) ’ Q, S; (d) ’ Q,R
4. (a)’ P,Q,S; (b)’ P,Q; (d) ’ R
(c) ’ P,Q,R;
5. (a)’ Q,R, S; (b)’ P,R, S; (c) ’ Q,R, S; (d)’ Q
6. (a)’P; (b)’ P,Q; (c)’R, S; (d)’ P,Q