P1. CARBOHYDRATES

Question 1

• Polyhyrdoxy aldehyde or ketone substances
• Compounds containing C, H, O
• Functional Groups: C=O [carbonyl groups] or CHO [functional group].

Answer 1

Carbohydrates

Question 2

4 Types of carbohydrates:

Answer 2

Monosaccharides
Disaccharides
Oligosaccharides
Polysacharrides

Question 3

examples of monosaccharides:

Answer 3

glucose
fructose

Question 4

examples of Disaccharides:

Answer 4

Sucrose (non-reducing)
Maltose (reducing)
Lactose (reducing)

Question 5

examples of Polysaccharides:

Answer 5

Starch
Glycogen
Cellulose
Chitin

Question 6

Types of Carbohydrates Testing:

Answer 6

1. Molish’s Test
2. Benedict’s Test
3. Fehling’s Test
4. Barfoed’s Test
5. Seliwanoff’s Test
6. Rapid Furfural Test
7. Osazone Test
8. Acid Hydrolysis Test

Question 7

• Carbohydrates when treated with concentrated H2SO4 undergo dehydration to give furfural derivatives.
• These compounds condense with ____ to form ____ colored products.

Answer 7

1. Molish’s test
2. a-naphthol
3. reddish-violet

Question 8

Reagents used in Molish’s Test:

Answer 8

• Molish’s reagent
• concentrated sulfuric acid (H2SO4)

Question 9

Composition of Molish’s reagent:

Answer 9

a-Naphthol in 95% ethanol

Question 10

Molish’s test is an ____ medium.

Answer 10

ACIDIC

Question 11

Substances tested in the Molish’s test:

1. Control [distilled water]
2. Glucose
3. Xylose
4. Lactose
5. Starch

What are the desciption of their visible results?

Answer 11

1. no purple ring at the junction of the two liquids
   2.-4. purple ring at the junction of two liquids

Question 12

• reduction of cupric ions to red cupruos oxide
• cupric hydroxide formed during the reaction is kept in solution by metal chelators like citrate

Positive result produces a green-yellow to brown or orange-red or brick red ppt (precipitate)

Answer 12

Benedict’s Test

Question 13

Reagents used in Benedict’s Test:

Answer 13

• Benedict’s reagent

Question 14

Composition of Benedict’s reagent:

Answer 14

copper sulfate
sodium carbonate
sodium citrate

Question 15

What are the positive color results of Benedict’s Test:

Answer 15

1. Green (+)
2. Yellow (+ +)
3. Orange (+ + +)
4. Red (+ + + +)

Question 16

approximate concentration of sugar in urine in color green:

Answer 16

0.1-0.5%

Question 17

approximate concentration of sugar in urine in color yellow:

Answer 17

0.5-1.0%

Question 18

approximate concentration of sugar in urine in color orange:

Answer 18

1.0-2.0%

Question 19

approximate concentration of sugar in urine in color red:

Answer 19

above 2.0%

Question 20

Benedict’s test is an ____ medium.

Answer 20

ALKALINE

Question 21

• tartarate solution chelates cupric ion, releasing its lowly for reduction thus preventing the formation of black cupric oxide.

Positive result produces a green-yellow to brown or orange-red ppt

Answer 21

Fehling’s Test

Question 22

Reagent used in Fehling’s test:

Answer 22

Fehling’s solution A & B.

Prepare fresh by mixing equal volumes of Fehling’s solutions A and B.

Question 23

Fehling’s solution A contains?

Answer 23

Copper Sulfate Solution

Question 24

Fehling’s solution B contains?

Answer 24

Potassium Hydroxide
Sodium Potassium Tartrate

Question 25

Fehling's Test is an ____ medium.

Answer 25

ALKALINE

Question 26

- differentiates between reducing **monosaccharides and disaccharides**. - **reduction** ## Footnote Positive result produces a **red ppt**. Negative result produces a **light-blue ppt(?)**

Answer 26

Barfoed’s Test

Question 27

Reagents used in Barfoed's Test:

Answer 27

Copper Acetate Glacial Acetic Acid

Question 28

Barfoed's Test is an ____ medium.

Answer 28

ACIDIC

Question 29

- **Concentrated HCl dehydrates ketohexoses** to form **furfural derivatives**. - condense with ____ to give ____ color solution. ## Footnote Positive results produces red color. Negative results produces pink color.

Answer 29

1. Seliwanoff's test 2. resorcinol 3. red

Question 30

Reagent's used in Seliwanoff's Test:

Answer 30

Seliwanoff's Reagent

Question 31

Composition of Seliwanoff's Reagent:

Answer 31

Resorcinol concentrated hydrochloric acid (HCl)

Question 32

Seliwanoff's Test is an ____ medium.

Answer 32

ACIDIC

Question 33

- test for ketohexoses. - Ketohexoses are rapidly converted to ____ by ____ and form ____ colored complex with 1% alcoholic ____.

Answer 33

1. Rapid Furfural Test 2. hydroxymethyl-furfural 3. HCl 4. purple 5. alpha-naphthol ## Footnote Positive results produces violet color within 30 sec of boiling (fructose)

Question 34

Reagents used in Rapid Furfural Test:

Answer 34

alcoholic alpha-naphthol HCl

Question 35

- **Conc. HCl** acts on ____ to form **furfurals**. - This condenses with **orcinol** to give ____ color compounds

Answer 35

1. Bial's Orcinol Test 2. pentoses 3. green ## Footnote Positive results produces **green** color solution.

Question 36

Reagents used in Bial's Orcinol Test:

Answer 36

Bial's reagent

Question 37

Composition of Bial's reagent:

Answer 37

diluted sol'n of ORCINOL in 30% HCL

Question 38

# Bial Orcinol Test: Substances Test: 1. Xylose 2. Glucose 3. Starch

Answer 38

Description of visible results: 1. blue-green color 2. yellow-brown color 3. no visible reaction

Question 39

Bial Orcino Test is an ____ medium.

Answer 39

ACIDIC

Question 40

- solution of **reducing sugar** when heated with **phenylhydrazine**, characteristic **yellow crystalline compounds** are formed. ## Footnote yellow crystalline compounts are called?

Answer 40

Osazone Test ## Footnote Osazone

Question 41

Reagents used in Osazone Test:

Answer 41

Phenylhydrazine Hydrochloride Glatial Acetic Acid Sodium Acetate

Question 42

# Results in Osazone Test: needle-shaped crystals arranged like a **broom**

Answer 42

Glucose/ Glucosazone

Question 43

# Results in Osazone Test: **sunflower**-shaped or **petal**-shaped crystals

Answer 43

Maltose/ Maltosazone

Question 44

# Results in Osazone Test: **hedgehog** or **pincushion** with **pins** or **powder puff** shaped crystals

Answer 44

Lactose/Lactosazone

Question 45

Osazone Test is an ____ medium.

Answer 45

WEAK ACIDIC