CARBOHYDRATES SEMIS

Question 1

A polyhydroxy aldehyde, a polyhydroxy ketone, or a compound that yields polyhydroxy aldehydes or polyhydroxy ketones upon hydrolysis.

Answer 1

CARBOHYDRATES

Question 2

Also known as simple sugars
Highly soluble in water
Less soluble in ethanol
Insoluble in ether

Answer 2

MONOSACCHARIDES

Question 3

Monosaccharides may also be classified into:

Answer 3

Tetroses
Pentoses
Hexoses

Question 4

Formed by two molecules monosaccharides

Answer 4

Disaccharides

Question 5

Are abundant in germinating barley

Answer 5

Maltose

Question 6

Also known as cane sugar or beet sugar

Answer 6

Sucrose

Question 7

This does not taste very sweet and is not fermented by yeast

Answer 7

Lactose

Question 8

Found in nature function either as structural units or for storage such as starch, dextrin, glycogen, insulin

Answer 8

Polysaccharides

Question 9

Give the 4 Polysaccharides for storage

Answer 9

Starch
Dextrin
Glycogen
Insulin

Question 10

Give the 3 general tests for carbohydrates

Answer 10

Molisch test
Bial’s orcinol test
Seliwanoff’s test

Question 11

The general test for carbohydrates

Answer 11

Molisch test

Question 12

In Molisch test the sugars are with a ____

Answer 12

A-naphthol

Question 13

The concentrated H2SO4 will dehydrate the sugar allowing it to react with the alcohol forming a _____

Answer 13

Furfural or hydroxymethyl-furfural

Question 14

When the Molisch test result is colorless, the result is?

Answer 14

Negative

Question 15

When the Molisch test result has a purple/violet ring, the result is?

Answer 15

Positive

Question 16

Used to determine the presence of pentoses and nucleotides and nucleotides that contain pentose sugars

Answer 16

Bial’s Orcinol Test

Question 17

When pentoses are treated with orcinol, furfurals are formed and they will yield a _____ compound in the presence of ferric ion

Answer 17

Blue-green compound

Question 18

Hydroxymethyl furfural is formed from hexoses to give ________ condensation products.

Answer 18

Yellow-brown

Question 19

In Bial’s Orcinol Test what color indicates pentoses

Answer 19

Blue-green color

Question 20

In Bial’s Orcinol Test what color indicates hexoses (negative)

Answer 20

Yellow-brown color

Question 21

This test is used to differentiate keohexoses from aldohexoses

Answer 21

Seliwanoff’s test

Question 22

This react faster with the solution containing hydrochloric acid and resorcinol

Answer 22

Ketohexoses

Question 23

The dehydrated positive ketohexoses form a ______

Answer 23

Bright cherry red condensation product

Question 24

Aldohexose yields a ______ that is a negative result

Answer 24

Pale pink color

Question 25

Any sugar that, in a solution, has an aldehyde or a ketone group

Answer 25

Reducing sugar

Question 26

Name the 8 reducing sugars

Answer 26

Glucose Galactose Fructose Ribose Glyceraldehyde Xylose Cellobiose Lactose

Question 27

Give the 3 test based on reducing property of sugars

Answer 27

Benedict’s test Barfoed test Tollen’s test

Question 28

It is a very sensitive test done in mildly alkaline conditions

Answer 28

Benedict’s test

Question 29

Benedict’s reagent are composed of;

Answer 29

CuSO4 Na2CO3 Sodium citrate

Question 30

When the Benedict’s reagent changes color the result is?

Answer 30

Positive

Question 31

Used to test the presence of glucose in urine

Answer 31

Benedict’s test

Question 32

Benedicts solution and simple carbohydrates are heated, the solution changes to what color?

Answer 32

Orange red/brick red

Question 33

What is the color of the Benedict’s solution when there are traces of reducing sugar?

Answer 33

Green/yellow

Question 34

What is the color of the Benedict’s solution when there are moderate amount of reducing sugar?

Answer 34

Orange red

Question 35

What is the color of the Benedict’s solution when there are large amount of reducing sugar?

Answer 35

Brick-red

Question 36

A copper reduction test in which heating a mixture of a monosaccharides in a given time interval results in the conversion of cupric ions in the reagent to cuprous ions with the formation of copper (I) oxide seen as a brick red precipitate in the mixture

Answer 36

Barfoed Test

Question 37

Copper reduction in Barfoes’s test occurs in an

Answer 37

Acidic medium (pH 4.6)

Question 38

In Barfoed test when red precipitate is formed faster what is present?

Answer 38

Monosaccharides

Question 39

In Barfoed test when red precipitate is formed slower what is present?

Answer 39

Disaccharide

Question 40

Also known as silver mirror test

Answer 40

Tollen’s test

Question 41

Sugars with ________ are capable reducing Tollen’s reagent

Answer 41

Aldehyde groups

Question 42

What is the Tollen’s reagent?

Answer 42

Ammoniacal solution of silver

Question 43

What is the color of a positive result Tollen’s test?

Answer 43

Gray - black precipitate (silver mirror)

Question 44

Reducing sugars that reduce silver ions in the test reagent to elemental silver

Answer 44

Glucose & lactose

Question 45

Common dietary monosaccharides

Answer 45

Glucose Galactose Fructose

Question 46

Examples of Pentose

Answer 46

Ribose & cellobiose

Question 47

2 Examples of Pentose

Answer 47

Ribose & cellubiose

Question 48

4 Examples of hexoses

Answer 48

Glucose, fructose, galactose, maltose

Question 49

Most important sugars

Answer 49

Pentoses & hexoses

Question 50

3 Examples of aldehyde

Answer 50

Glucose, maltose, galactose

Question 51

Example of ketone

Answer 51

Fructose

Question 52

Molisch test is based on dehydration by ____

Answer 52

Sulfuric acid