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Biomolecules > Qualitative Analysis of Carbohydrates > Flashcards

Qualitative Analysis of Carbohydrates Flashcards

1
Q

skeletons of
covalently bonded carbon atoms

A

organic compounds

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2
Q

are the
major components of cells and tissues

A

organic compounds

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3
Q

They provide energy for life processes, participate and
regulate metabolic reactions, and transmit information

A

organic compounds

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4
Q

Organic molecules in living organisms
can be classified either

A

carbohydrates
proteins
lipids
nucleic acids

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5
Q

are compounds that contain carbon, hydrogen and oxygen.

A

carbohydrates

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6
Q

includes a variety of compounds such as sugars, starches and cellulose.

A

carbohydrates

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7
Q

serve as energy sources for cells, while cellulose are structural components of the walls that
surround plant cells

what compounds (2)

A

sugars
starches

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8
Q

carbohydrates that have one sugar molecule

A

monosaccharides

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9
Q

carbohydrates with two sugar molecules

A

dissacharides

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10
Q

carbohydrates with many sugar unts

A

polysaccharides

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11
Q

is a chemical test which is used to check for the presence of carbohydrates in a given analyte

A

Molisch’s test

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12
Q

a solution of α-naphthol in ethanol

A

Molisch’s reagent

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13
Q

involves the addition of a solution of α-naphthol in ethanol to the analyte and the subsequent addition of a few drops of concentrated H2SO4 to the mixture

A

Molisch’s test

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14
Q

Molisch’s test reagents (2)

A

H2SO4 (sulfuric acid)
α-naphthol in ethanol

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15
Q

The formation of a ___or a ____-red ___at the point of contact between the H2SO4 and the analyte + Molisch’s reagent mixture confirms the presence of carbohydrates in the analyte.

A

purple
purplish-red

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16
Q

A positive reaction for Molisch’s test is given by almost all carbohydrates but exceptions

A

tetrose
triose

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17
Q

some compounds aside from carbohydrates that give positive results for Molisch’s test

A

glycoproteins
nucleic acids

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18
Q

tend to undergo hydrolysis when exposed to strong mineral acids and form monosaccharides

A

glycoproteins
nucleic acids

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19
Q

In Molisch’s test, the carbohydrate (if present) undergoes dehydration upon the introduction of concentrated hydrochloric or sulphuric acid, resulting in the formation of an ____

A

aldehyde

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20
Q

undergoes condensation along with two phenol-type molecules (such as α-naphthol, resorcinol, and thymol), resulting in the formation of a purple or reddish-purple coloured complex.

What kind of compound formed in molisch’s test

A

aldehydes

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21
Q

study the molisch’s test principle

A

+1

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22
Q

Molisch’s teast procedure

A
  1. Add 2 drops of Molisch reagent (prepared by dissolving 0.1g of ∞napthol in 2 mL of
    ethanol) to 2 mL of sugar solution (glucose, fructose, galactose, sucrose, maltose,
    lactose, starch) and mix.
  2. Incline the tube, and gently add 2 mL of concentrated sulfuric acid down the side of
    the test tube.
  3. A purple color at the interface between the sugar and acid indicates a positive result.
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23
Q

is a chemical test that can be used to check for the presence of reducing sugars
in a given sample

A

Benedict’s test

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24
Q

compounds that Benedict test can be used to dientify

A

free ketone/aldehyde

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25
Q

complex mixture of sodium citrate,
sodium carbonate, and the pentahydrate of copper(II) sulfate

A

Benedict’s solution

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26
Q

what is Benedict’s solution made up of (3)

A

sodium citrate
sodium carbonate
copper (II) sulfate

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27
Q

All those carbohydrates which contain a free aldehyde or Ketonic group and reduce Fehling’s solution and Tollen’s reagent are referred as a

A

reducing sugar

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28
Q

galactose, glucose, glyceraldehyde, fructose, ribose, and xylose

examples are

A

reducing sugar

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29
Q

When exposed to ____ sugars, the reactions undergone by Benedict’s reagent result in the
formation of a brick-red precipitate, which indicates a positive Benedict’s test

A

reducing

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30
Q

When a reducing sugar is subjected to heat in the presence of an alkali, it gets converted into
an ___

A

enediol

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31
Q

Therefore, when reducing sugars
are present in the analyte, the cupric ions (Cu2+) in Benedict’s reagent are reduced to ___ ions

A

cuprous (Cu+)

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32
Q

reagent that can be prepared by mixing 17.3 grams of copper sulfate
pentahydrate (CuSO4.5H2O), 100 grams of sodium carbonate (Na2CO3), and 173 grams of
sodium citrate in distilled water (required quantity).

A

Benedict’s reagent

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33
Q

acts a source
of Cu
2+ ions in Benedict’s reagent

A

copper sulfate

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34
Q

in Benedcit’s reagent, provides an alkaline medium

A

sodium carbonate

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35
Q

review the results of Benedict’s test based on color

A

+1

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36
Q

can also be used to check for the presence of glucose in a
urine sample since this test detects any aldehydes and α-hydroxy ketones and glucose is an
aldose whose open-chain forms an aldehyde group, the test yields a positive result when
glucose is present in the analyte

A

Benedict’s test

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37
Q

However, a positive reaction can also be given by the
presence of ___ ____ in urine

A

ascorbic acid
homogentisic acid

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38
Q

False positive reactions may also be obtained if certain drugs are present, e.g. salicylates,
penicillin, streptomycin, isoniazid, and p-aminosalicyclic acid.

what kind of test

A

Benedict’s test

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39
Q

Chemicals present in a concentrated urine which may reduce Benedict’s reaction include

A

creatinine
urate
ascorbic acid

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40
Q

Benedict’s test procedure

A
  1. Add 1 mL of the 2% sugar solution (glucose, fructose, galactose, sucrose, maltose,
    lactose, starch) to 5 mL of Benedict’s solution (prepared by mixing 10 g sodium
    carbonate and 17.3 g monosodium citrate dehydrate in 85 mL water, and while
    stirring add 10 mL of water containing 1.73 g copper sulfate then to a final volume of
    100 mL).
  2. Place test tubes in a boiling water bath.
  3. Formation of red to brick precipitate is a positive result.
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41
Q

an be defined as the most important complex carbohydrate compounds. It is a polysaccharide and glucoside reserve of plants. It is a renewable and biodegradable product, so it can act as a perfect raw material and a substitute for fossil-fuel components in making detergents, glues, plastics, etc.

A

starch

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42
Q

comprise a large number of glucose units that are bound together by glycosidic bonds and are produced by all vegetables and other plant sources through the process of photosynthesis.

A

starch

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43
Q

performed to test the presence of carbohydrates/starch

A

iodine test

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44
Q

is a chemical test used to distinguish mono- or disaccharides from certain polysaccharides like amylase, dextrin, and glycogen.

A

iodine test

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45
Q

based on the fact that polyiodide ions form colored adsorption complex with helical chains of glucose residue of amylase (blue-black), dextrin (black), or glycogen (reddish-brown).

A

iodine test

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46
Q

what compounds remain colorless in iodine test (3)

A

monosaccharides
disaccharides
branched polysaccharides (e.g. cellulose)

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47
Q

produces an orange-yellow hue in iodine test

A

amylopectin

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48
Q

aqueous solution of elemental iodine and potassium iodide

A

Lugol’s iodine

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49
Q

on its own is insoluble in water

A

Iodine

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50
Q

Addition of potassium iodine results in a reversible reaction of the iodine ion with iodine to form a

A

triiodide ion

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51
Q

The appearance of blue-black or purple color represents a ___ test, indicating the presence of start

A

positive

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52
Q

This test cannot be performed under acidic conditions as the starch hydrolyses under such circumstances

A

acidic conditions

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53
Q

iodine test procedures

A
  1. Add 2-3 drops of Lugol/s iodine solution or (pepared by dissolving 1g of iodine and 2
    g potassium iodide in 100 mL distilled water) to 5 mL of 2% sugar solution (glucose,
    fructose, galactose, sucrose, maltose, lactose, starch).
  2. Starch gives a blue-black color.
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54
Q

is a chemical test used for detecting the presence of monosaccharides.

A

Barfoed’s test

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55
Q

reduction of cupric (II) acetate to cuprous (I) oxide (Cu2O),

A

Barfoed’s test

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56
Q

forms a brick-red precipitate when positive

A

Barfoed’s test

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57
Q

may react, but the reaction is much slower because they have to get hydrolyzed first and then react with the reagent cupric acetate to produce cuprous oxide

A

Disaccharides

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58
Q

brick red precipitate in Barfoed’s test

A

curpous (I) oxide (Cu2O)

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59
Q

This test is used to distinguish reducing monosaccharides from disaccharides by controlling pH and the time of heating.

A

Barfoed’s test

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60
Q

If a red precipitate is formed within two minutes, it means that a ____is present. If the red precipitate is formed after ten minutes of heating, a ___is present.

A

monosaccharides
disaccharides

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61
Q

Barfoed’s reagent is similar to Benedict’s reagent except that the pH is lower/higher (around 4.5), and the heating time is reduced to two minutes.

A

lower

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62
Q

____test would determine if the sample is a reducing sugar, and ____test would determine if it is a monosaccharide or disaccharide.

A

Benedict’s test
Barfoed’s test

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63
Q

Barfoed’s reagent is composed of
(2)

A

copper acetate monohydrate
glacial acetic acid

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64
Q

Barfoed’s reagent

A
  1. Add 1 mL of the 2% sugar solution (glucose, fructose, galactose, sucrose, maltose,
    lactose, starch) to 3 mL of Barfoed’s reagent (Mix 7 g of copper acetate monohydrate
    with 1 mL of glacial acetic acid in distilled water and make the final volume 100
    mL).
  2. Place test tubes into boiling water bath and heat for 3-10 minutes. Remove the tubes
    from the bath and allow cooling.
  3. Formation of scanty red precipitate is a positive result.
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65
Q

is used to differentiate between sugars that have a ketone group (ketose) and sugars that have an aldehyde group (aldoses).

A

Seliwanoff’s test

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66
Q

Seliwanoff’s reagent consists of

A

resorcinol
concentrated HCl

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67
Q

are more rapidly dehydrated than aldoses

A

ketoses

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68
Q

Ketoses undergo dehydration in the presence of concentrated acid to yield

A

5-hydroxymethy furfural

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69
Q

complex produced when dehydrated ketose reacts with two equivalents of resorcinol in series of condensation reactions

A

xanthenoid

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70
Q

deep cherry red complex seen in positive seliwanoff’s test

A

xanthenoid

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71
Q

Other carbohydrates like sucrose and inulin also give a positive result for this test as these are hydrolyzed by acid to give ___

A

fructose

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72
Q

is used in the method for the colorimetric determination of fructose in fermentation media.

A

Selifwanoff’s color reaction

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73
Q

Seliwanoff’s test procedures

A
  1. Add 1 mL of 1% sugar solution (glucose, fructose, galactose, sucrose, maltose,
    lactose, starch) to 10 mL of the reagent (Dissolve 0.1 g resorcinol in 33 mL
    concentrated hydrochloric acid (HCl) and make the final volume of 100 mL).
  2. Heat the solution in boiling water bath for 5 minutes.
  3. A deep cherry or red color within 5 minutes is a positive result.
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74
Q

Silver mirror test (Tollen’s reagent) procedures

A
  1. Wash the tube with a 10% solution of sodium hydroxide (1g NaOH in 10 mL distilled
    water).
  2. Add 2 mL of a 5% (0.5g in 10 mL distilled water) silver nitrate solution (AgNO3) into
    the washed tube, then add one drop of the 10% sodium hydroxide solution.
  3. Add one drop of 28% ammonia solution (add more drops if necessary). Shake
    constantly until silver oxide dissolves, then add 1 mL of 2% sugar solution.
  4. The formation of a silver mirror in the inner surface of the test tube is a positive
    result.
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75
Q

is a qualitative laboratory test used to distinguish between an aldehyde and a ketone by exploiting the fact that aldehydes are readily oxidized

A

Tollens’ test

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76
Q

Tollen’s reagent is composed of

A

alkaline silver nitrate
aqueous ammonia

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77
Q

alkaline silver nitrate chemical formula

A

AgNo3

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78
Q

aqueous ammonia solution

A

NH4OH

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79
Q

The reaction is accompanied by the reduction of silver ions into metallic silver

A

Tollen’s test

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80
Q

must be worn all the time inside the laboratory and especially
when handling the following chemicals

A

protective gloves

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81
Q

may cause liver, kidney damage, blood abnormalities, and severe eye
irritation

A

1-Naphthol

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82
Q

is extremely corrosive and can cause serious
burns when not handled properly

A

Sulfuric acid

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83
Q

(may cause eye and skin irritation

A

resorcinol

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84
Q

may explode if heated. Causes severe skin burns

A

Ammonia

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85
Q

If swallowed, causes severe irritation and chemical burns to the
gastrointestinal tract, and can cause permanent eye damage/blindness

A

Sodium hydroxide

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86
Q

study the table for positive reactions in sugar solution

A

+1

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87
Q

most abundant organic compounds found in living organisms

A

carbohydrates

88
Q

carbohydrates is composed of

A

Carbon, Hydrogen, and Oxygen

89
Q

 act as the primary source to provide energy for functioning of living organisms

A

carbohydrates

90
Q

 considered as hydrates of carbon

A

carbohydrates

91
Q

 called saccharides

A

carbohydrates

92
Q

carbohydrates are what

A

polyhydroxy aldheydes or polyhydeoxy ketones

93
Q

polyhydroxy aldehydes and ketones and their anhydrides

A

carbohydrates

94
Q

 contain potentially active aldehydes or ketone groups and their derivatives

A

carbohydrates

95
Q

carbohydrates  can be represented by stoichiometric formula

A

(CH2O)n

96
Q

is characterized by the presence of fructose in the urine after ingesting fructose. It arises as a result of a deficiency of the hepatic enzyme fructokinase and is an autosomal recessive genetic disorder.

A

fructosuria

97
Q
  • Urine galactose can be elevated in patients with galactosemia caused by either GALT deficiency or galactokinase deficiency
A

galactosuria

98
Q

cannot be hydroylzed into simpler carbohydrates

A

monosaccharides

99
Q

monosaccharides can be classified into based on number of carbon atoms present

A

triose
tetrose
pentose
hexose
heptose

100
Q

carbohydrates classified based on the functional group present

A

aldose
ketose

101
Q

example of monosaccharides

A

xylose
glucose
galactose
fructose

102
Q

give rise to two monosaccharide units upon hydrolysis

A

disaccharides

103
Q

formed when two monosaccharides undergo a condensation reaction

A

disaccharides

104
Q

reaction that involves the elimiation of a small molecule, such as water, from the functional groups only

A

disaccharides

105
Q

polymeric carbohydrate structures, formed of repeating units of either monosaccharides or disaccharides joined together by glycosidic bonds

A

polysaccharides

106
Q

monosaccharides + disaccharides forming polysaccharides are joined together by what bond

A

glycosidic bond

107
Q

contain more than 10 monosaccharide units

A

polysaccharide

108
Q

primary function of polysaccharides

A

energy storage
food reserve

109
Q

3 important polysaccharides

A

starch, glycogen, cellulose

110
Q

monosaccharide that contains only one aldehyde group per molecule

A

aldose

111
Q

monosaccharide that contains only one ketone group per molecule

A

ketose

112
Q

monosaccharide that contains five carbon atoms

A

pentose

113
Q

monosaccharide that contains five carbon atoms​

A

pentoses

114
Q

hexose with an aldehyde group on one end​

A

aldohexose

115
Q

ketone-containing hexose​

A

ketohexose

116
Q

a polysaccharide​

A

amylose

117
Q

a straight chain polymer of D-glucose units​

A

amylose

118
Q

constitutes about 20% of the starch​

A

amylose

119
Q

a polysaccharide​ that has a branched biopolymer consisting of linear chains of glucose residues

A

glycogen

120
Q

the principal storage form of glucose in animal and human cells​

A

glycogen

121
Q

a polysaccharide​
consists of a linear chain of β(1→4) linked D-glucose units​

A

cellulose

122
Q

an important structural component of the primary cell wall of green plants​

A

cellulose

123
Q

a monosaccharide​

contains five carbon atoms (pentose), a formyl and aldehyde functional group​
A

xylose

124
Q

xylose is what (aldose,ketose, hexose,pentose)

A

aldopentose

125
Q

a monosaccharide​

contains six carbon atoms (hexose) and an aldehyde functional group (aldose).​

Aldohexose​

widely used aldohexose in living organisms​
A

glucose

126
Q

a monosaccharide​

contains six carbon atoms (hexose) and an aldehyde functional group (aldose)​

Aldohexose​

not normally found in nature but it is mostly hydrolyzed from lactose
A

galactose

127
Q

monosaccharide​

contains six carbon atoms (hexose) and a ketone functional group (ketose)​

Ketohexose​

Also known as levulose​

A

fructose

128
Q

fructose is also known as

A

levulose

129
Q

a disaccharide​

contains the units of galactose and glucose​
A

lactose

130
Q

a disaccharide​

contains two units of glucose
A

maltose

131
Q

a disaccharide​

contains the units of glucose and fructose.​

commonly referred to as "table sugar"​
A

sucrose

132
Q

sucrose is commonly referred to as

A

table sugar

133
Q

Some Important Tests for the Detection of Carbohydrates​
​

A

Molish Test​

Fehling’s Test​

Benedict’s Test​

Tollen’s test​

Iodine Test​

134
Q

used to detect the presence of carbohydrates in different samples.​

A

Molisch’s test

135
Q

can be used to detect the formation of carbohydrates as a by-product in different reactions and distinguish it from other biomolecules.​

A

Molisch test

136
Q

A test for all carbohydrates.​

Indicates presence of a carbohydrate

A

Molisch test

137
Q

in Molisch test, which give a rapid positive test while these other saccharides react slower

A

Monosaccharides give a rapid positive test.​

Disaccharides and polysaccharides react slower

138
Q

Principle of Molisch test

Hydrolysis of carbohydrates to ____ form​

A

monosaccharide

139
Q

Principle of Molisch test

Dehydration of monosaccharide to ___ derivatives ​

A

furfural

140
Q

When carbohydrates are exposed to concentrated H2SO4, they undergo dehydration to form

A

furaldehyde derivatives

141
Q

pentoses when reacting with H2SO4 form

A

furfural

142
Q

hexoses form what when reacting with H2SO4

A

hydromethyl furfural

143
Q

what reagent does carbohydrate condenses with to form a colored interphase

A

a-naphthol

144
Q

The formation of the purple colored ring occurs at the interface between the ____ ___and the test solution.

A

sulfuric acid

145
Q

remains above the test solution as the acid is denser than the test solution in Molisch’s test

A

Sulfuric acid

146
Q

Molisch test is positive for what

A

carbohydrates

147
Q

reagents of Molisch test

A

a-naphthol and 95% ethanol

148
Q

chemical analytical method used for the detection of reducing sugar in a solution.​

A

benedict’s test

149
Q

a qualitative test often used for the differentiation of carbohydrates (saccharides/sugars) into reducing and non-reducing types.​

A

benedict’s test

150
Q

It is widely used to identify monosaccharides (simple sugars) and other reducing sugars

A

Benedict’s test

151
Q

Benedict’s test is used as an alternative to

A

Fehling’s test

152
Q

To detect the presence of reducing sugar in the sample solution​

To diagnose diabetes mellitus by detecting glucose in the urine sample​

To estimate the concentration of reducing sugar in the sample solution​

To differentiate and identify the extracted carbohydrates ​

​what test

A

Benedict’s test

153
Q

Carbohydrates with a free aldehyde or keto group have the ability to reduce various metallic ions.

what test

A

Beenedict’s test

154
Q

In this test, ___ ions are reduced to ___ions by the ____formed from sugars in the alkaline medium of Benedict’s reagent.​

A

Cupric
Cuprous
Enediols

155
Q

Benedict’s test Result interpretation based on color

Blue
Green
Green ppt.
Yellow ppt.
Orange ppt.
Brick red ppt.

A

B - No reducing sugar
G - trace reducing sugar (<0.5g%)
GPPT- trace reducing sugar (0.5-1%)
YPPT - low reducing sugar (1-1.5g%)
OPPT - moderate reducing sugar (1.5-2g%)
RPPT - high reducing sugar (>2g%)

156
Q

what disaccharide is positive for benedict’s test

A

lactose
maltose

157
Q

Benedict’s reagent

A

Copper sulphate, sodium citrate and sodium carbonate

158
Q

positive for benedict’s test is indicated by

A

brick red precipitate

159
Q

dissociate to give sufficient cupric ions (in the form of cupric hydroxide) for the reduction reactions to occur.​

A

copper sulfate

160
Q

keeps the cupric hydroxide in solution without getting precipitated​

A

sodium citrate

161
Q

ake the pH of the medium alkaline

A

sodium carbonate

162
Q

In the alkaline medium, sugars form ___ which are powerful ___agents.

A

enediols
reducing

163
Q

reduce blue cupric hydroxide to insoluble yellow to red cuprous oxide in Benedict’s test

A

Enediols

164
Q

a chemical test used to distinguish mono- or disaccharides from certain polysaccharides like amylase, dextrin, and glycogen.​

A

Iodine test

165
Q

a test for polysaccharides​

​

A

Iodine test

166
Q

To detect the presence of polysaccharides, primarily starch.​

This test is used to detect the presence of starch in various samples.​

Similarly, this test is performed to test the process of photosynthesis in plants.

what test

A

iodine test

167
Q

forms a coordinate complex between the helically coiled polysaccharide chain and iodine centrally located within the helix due to adsorption

A

iodine

168
Q

The color obtained depends upon the ___ of the unbranched or linear chain available for complex formation in Iodine test

A

length

169
Q

The appearance of blue-black or purple color represents a ___ test, indicating the presence of starch.​

A

positive

170
Q

iodine test is a positive for what

A

amylose
deep blue color

171
Q

reagents of Iodine test

A

2% solution of KI in water with few crystals of iodine

172
Q

is a chemical test used to detect the presence of monosaccharides which detects reducing monosaccharides in the presence of disaccharides.​

A

Barfoed’s test

173
Q

To detect reducing carbohydrates.​

To distinguish reducing monosaccharides from disaccharides.​

what test

A

Barfoed’s test

174
Q

This test is used to identify reducing monosaccharides and distinguish the reducing disaccharides from reducing monosaccharides.

what test

A

Barfoed’s test

175
Q

Barfoed’s test determines the presence of reducing sugars. Aldoses and Ketoses can reduce cupric ions (II) to cupric oxide (I) even in ___ conditions

A

acidic

176
Q

This test also distinguishes monosaccharides from disaccharides by what factor

A

controlling pH
time of heating

177
Q

react very fast (within 3-5 mins) in Barfoed’s test

A

monosaccharides

178
Q

react very slowly (more than 5 mins) in Barfoed’s test

A

Disaccharides

179
Q

The presence of red precipitate detects the presence of reducing ____ in the sample.​

Barfoed’s test

A

monosaccharides

180
Q

If the color appears within the first few minutes, the sample contains reducing monosaccharides.

what test

A

Barfoed’s test

181
Q

However, if the color appears later than the first 3 minutes, the sample is of reducing disaccharides.​

what test

A

Barfoed’s test

182
Q

A test to distinguish ketoses from aldoses in carbohydrates.​

A

Resorcinol (Seliwanoff)’s test

183
Q

identifies ketoses since the reaction occurs fast with ketoses.​

A

Resorcinol (Seliwanoff’s) Test

184
Q

also react but at much slower rate. in Seliwanoff’s test

A

aldose sugars

185
Q

To detect the presence of ketohexoses in a given sample.​

To distinguish ketoses from aldoses.​

​what test

A

Resorcinol (Seliwanoff’s test)

186
Q

is used in the method for the colorimetric determination of fructose in fermentation media

A

Seliwanoff’s color reaction

187
Q

A modified version of this test can be used for the determination of the concentration of ketoses in a given sample.

A

Seliwanoff’s test

188
Q

Seliwanoff’s test is used to distinguish aldoses from ketoses. On treatment with conc. acid, ___ are dehydrated more rapidly to give furfural derivatives and on condensation with resorcinol give cherry red complex. ​

A

ketoses

189
Q

Ketohexoses when treated with hydrochloric acid form ____

A

5-hydroxy methyl furfural

190
Q

a cherry red colored precipitate within 5 minutes is obtained in Seliwanoff’s test indicate

A

presence of ketones

191
Q

If the reaction is allowed for longer time, aldoses also produce positive results. A faint __ color is produced.​

A

red

192
Q

The formation of the cherry red-colored complex indicates a positive result which means that the given sample contains

A

ketones

193
Q

The absence of such color or the appearance of the color after a prolonged period of time indicates a negative result which means that the test sample doesn’t have ____ .​

Seliwanoff’s test

A

ketones

194
Q

Seliwanoff’s test is positive for

A

Ketose Sugars

195
Q

Ketose sugars include

A

Sucrose
Fructose

196
Q

positive seliwanoff’s test looks like

A

cherry red solution

197
Q

reagent of Seliwanoff’s test

A

Resorcinol
Hcl

198
Q

chemical test used to differentiate reducing sugars from non-reducing sugars.​

A

silver mirror test (Tollen’s reagent)

199
Q

This test is also called the silver mirror test based on the end product of this test

A

Tollen’s test

200
Q

To distinguish reducing sugars from non-reducing sugars.​

To detect the presence of aldehyde containing carbohydrates and differentiate them from ketone containing carbohydrates.​

what test

A

Tollen’s test

201
Q

is routinely performed in chemical laboratories for the qualitative organic analysis, which distinguishes aldehydes from ketones.​

A

Tollen’s test

202
Q

is also used for the differentiation of reducing sugars from non-reducing sugars.​

A

Tollen’s test

203
Q

Tollen’s reagent is composed of

A

ammonia
silver nitrate
sodium hydroxide

204
Q

On reacting with carbohydrate, elemental ___ is precipitating out of the solution, occasionally onto the inner surface of the reaction vessel. This produces silver mirror on the inner wall of the reaction vessel.​

A

silver

205
Q

The formation of a dark grey precipitate or silver mirror on the bottom and sides of the test tube indicates a positive result, which means that the given sample contains reducing ____

A

sugars/aldoses

206
Q

The absence of such precipitate indicates a ___ result, which means that the test sample doesn’t have reducing sugars/ aldoses/ α-hydroxy ketoses.​

A

negative

207
Q

Study flowchart (in your gallery)

A

+1

208
Q

Glucose result on the ff test:

Molisch
Fehling
Benedict
Tollen
Iodine

A

M - + (purple ring)
F - + (red precipitate)
B - + (red precipitate)
T - + (silver mirror)
I - - (no reaction)

209
Q

Lactose result on the ff test:

Molisch
Fehling
Benedict
Tollen
Iodine

A

M - + (purple ring)
Fehling - + (red precipitate)
Benedict - + (red precipitate)
Tollen - + (silver mirror)
Iodine - - (no rx)

210
Q

Sucrose result on the ff test:

Molisch
Fehling
Benedict
Tollen
Iodine

A

m +
f -
b -
t -
i -

211
Q

starch result on the ff test:

Molisch
Fehling
Benedict
Tollen
Iodine

A

m - +
f - -
b - -
t - -
i - +

212
Q

Based on the reactivity with Tollen’s, Benedict’s or Fehling’s reagent, carbohydrates are classified as;​

A

Reducing
Non reducing

213
Q

Sugar with free aldehyde or ketone group​

All monosaccharides and most of the disaccharides

A

reducing sugars

214
Q

can reduce Tollen’s, Benedict’s or Fehling’s reagents​

A

reducing sugars

215
Q

They do not get oxidized​

Sucrose is their most common source​

A

non reducing sugars

216
Q

Cannot reduce Tollen’s, Benedict’s or Fehling’s reagents​

A

non-reducing sugars

Biomolecules (19 decks)

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