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Biomolecules Lab Finals > Qualitative Analysis of Carbohydrates > Flashcards

Qualitative Analysis of Carbohydrates Flashcards

1
Q

most abundant organic compounds found in living organisms and are composed of carbon, hydrogen, and oxygen.

A

Carbohydrates

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2
Q

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

A

Carbohydrates

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3
Q

considered as hydrates of carbon

A

carbohydrates

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4
Q

general formula of Carbohydrates

A

Cx(H2O)y

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5
Q

defined as polyhydroxy aldehydes or polyhydroxy ketones or the compounds which produces such products on hydrolysis

A

carbohydrates

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6
Q

carbohydrates are defined as _________________________or the compounds which produces such products on hydrolysis

A

polyhydroxy aldehydes
polyhydroxy ketones

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7
Q

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

A

reducing sugars
non-reducing sugars

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8
Q

carbohydrates that can reduce Tollen’s, Benedict’s or Fehling’s reagent are called _____________

A

reducing sugars

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9
Q

sugar with free aldehyde or ketone group

A

reducing sugars

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10
Q

true or false: all monosaccharides and most of the disaccharides are reducing sugars

A

true

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11
Q

Carbohydrates that cannot reduce Tollen’s, Benedict’s or Fehling’s reagents are called

A

non-reducing sugars

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12
Q

True or False: Maltose and Lactose are non-reducing sugars

A

False; reducing

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13
Q

True or False: Sucrose is a reducing sugar

A

False; non-reducing

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14
Q

What are the different tests for the detection of carbohydrates?

A

Molisch’s test
Fehling’s test
Benedict’s test
Tollen’s test
Iodine test

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15
Q

10% alcoholic solution of α-naphthol

A

Molisch’s reagent

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16
Q

What is used in Molisch’s test?

A

concentrated sulfuric acid

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17
Q

carbohydrates undergo dehydration by sulfuring acid to form _______ that reacts with α-naphthol

A

furfural (furfuraldehyde)

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18
Q

carbohydrates undergo dehydration by sulfuring acid to form furfural that reacts with α-naphthol to form a _______ colored product

A

violet

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19
Q

carbohydrates undergo dehydration by sulfuring acid to form furfural that reacts with α-naphthol to form a violet colored product

A

molisch’s test

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20
Q

Fehling’s A is a _____________ while Fehling’s B solution is potassium sodium tartrate

A

copper sulphate

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21
Q

Fehling’s B solution is ___________ while Fehling’s A is copper sulphate

A

potassium sodium tartrate

22
Q

On heating, carbohydrate reduces deep blue solution of __________ to red precipitate of insoluble copper oxide

A

copper II ions

23
Q

On heating, carbohydrate reduces deep blue solution of copper II ions to red precipitate of insoluble ____________

A

copper oxide

24
Q

The copper ions present in Fehling’s solution in +3 state is reduced to _________________

A

+2 oxidation state

25
Q

In alkaline medium, copper ions present in Fehling’s solution is precipitated as _____________

A

red cuprous oxide

26
Q

distinguishes reducing sugar from non-reducing sugar

A

Benedict’s test

27
Q

Benedict’s reagent contains

A

Blue copper (II) ions (Cu2 cupric ions)

28
Q

Benedict’s reagent contains Blue copper (II) ions (Cu2 cupric ions) that are reduced to

A

copper (I) ions (Cu2+ cupric ions)

29
Q

In alkaline medium, __________ converts glucose to enediol which reduce cupric to cuprous forming cuprous hydroxide

A

sodium carbonate

30
Q

In alkaline medium, sodium carbonate converts __________ to enediol which reduce cupric to cuprous forming cuprous hydroxide

A

glucose

31
Q

In alkaline medium, sodium carbonate converts glucose to ________ which reduce cupric to cuprous forming cuprous hydroxide

A

enediol

32
Q

reduce cupric to cuprous forming cuprous hydroxide

A

enediol

33
Q

Where is the Benedict’s solution kept?

A

sodium citrate

34
Q

upon boiling, Benedict’s reagent forms

A

cuprous oxide

35
Q

ammoniacal silver nitrate solution

A

Tollen’s reagent

36
Q

Carbohydrates reacts with Tollens reagent forms a ________ mirror on the inner walls of the test tibe

A

silver

37
Q

used to detect presence of starch

A

Iodine test

38
Q

True or False: Iodine is not much soluble in water

A

true

39
Q

Where is iodine solution prepared?

A

dissolving iodine in water in the presence of potassium iodide

40
Q

Iodine dissolved in an aqueous solution of potassium iodide reacts with starch to form a ____________ which gives characteristics blue black color

A

starch/iodine complex

41
Q

True or False: In iodine test, when heating the blue color disappears and on cooling the blue color reappears

A

True

42
Q

positive in molisch’s test

A

maltose
lactose
sucrose

43
Q

negative on molisch’s test

A

starch

44
Q

Fehling’s test positive

A

maltose
lactose
sucrose

45
Q

Fehling’s test negative

A

starch

46
Q

Benedict’s test positive

A

maltose lactose sucrose

47
Q

Benedict’s test negative

A

starch

48
Q

Tollen’s test positive

A

maltose
lactose

49
Q

Tollen’s test negative

A

sucrose
starch

50
Q

Iodine test positive

A

starch

51
Q

iodine test negative

A

maltose lactose sucrose

Biomolecules Lab Finals (3 decks)

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