Carbohydrates

Question 1

State 7 Differences between Monosaccharides and Polysaccharides.

Answer 1

Monosaccharides Polysaccharides
Soluble Insoluble
sweet Not sweet
Small Large
No glycosidicbonds Glycosidicbonds present
Osmotic effect No osmotic effect
Cannot be hydrolysed Can be hydrolysed
monomer Polymer

Question 2

What are Monosaccharides?

Answer 2

these are simple sugars, with the general
formula (CH20)n, where ncan be 3–7. The most common n = 6.
Monosaccharides provide a quick source of energy.

Question 3

What are Hexose Sugars?

Answer 3

Hexose sugars (6C) have a ring structure made of 5 carbons and 1
oxygen and an additional carbon above or below the ring.
Numbering of hexoses starts with the carbon on the right of
oxygen

Question 4

Give 3 examples of hexose monosaccharides.

Answer 4

Glucose
Galactose
Fructose

Question 5

Statet he general formula of Glucose

Answer 5

C6H12O6

Question 6

What is the name given to different forms Glucose can exist in and state the name of the forms.

Answer 6

Glucose exists in different forms called structural isomers. Two common
isomers are alpha glucose and beta glucose.

Question 7

What is the difference between alpha glucose and beta glucose?

Answer 7

The only difference between these two isomers is the position
of the –OH group attached to carbon 1. In alpha glucose it is
below the carbon and in beta glucose it is above the carbon

Question 8

Where is fructose found?

Answer 8

is the main sugar in fruits and
nectar. It is sweeter than glucose

Question 8

What is the role of Galactose?

Answer 8

has an important
role in the production of glycolipids and glycoproteins.

Question 9

What are the two important pentose molecules?

Answer 9

The structural isomers ribose and deoxyribose

Question 10

How are disaccharides formed?

Answer 10

2 monosaccharides joined by a glycosidic bond during a
condensation reaction which involves the removal of 1 water
molecule to form disaccharides

Question 11

How are Polysaccharides formed?

Answer 11

Plenty disccharides joined by glycosidic bonds to form
polysaccharides such as glycogen and starch

Question 12

What type of reaction is the formation of a disaccharide? why?

Answer 12

condensation , because we form water aswell

Question 13

What type of reaction is the Deconstruction of a disaccharide? why?

Answer 13

Hydrolisis, we use up water

Question 14

Name the three Disaccharides, their monosaccharide components, and the linkage they form.

Answer 14

Sucrose is made up of Glucose and Fructose and is made by a 1,4-alpha glycosidic bond
Maltose is made up of two Glucose molecules and is made by a 1,4-alpha glycosidic bond
Lactose is made up of Glucose and Galactose and is made by a 1,4-beta glycosidic bond

Question 15

Why do blood sugar levels change differently when the sugar comes from monosacchardies and Polysaccharide, Disaccharides?

Answer 15

 Monosaccharides are easily absorbed into the blood and
cause a spike in blood sugar levels.
 Polysaccharides and disaccharides are complex
carbohydrates.
 Complex carbohydrates have to be digested to
monosaccharides before absorption.
 Time is need to digest complex carbohydrates and so
the monosaccharides are slowly released.
 Thus, complex carbohydrates do not cause a spike in
blood sugar as they are gradually released.

Question 16

What kind of reaction is used to make Polysaccharides?

Answer 16

Polysaccharides are polymers containing many
monosaccharides linked by glycosidic bonds. Like
disaccharides, polysaccharides are formed by condensation
reactions.

Question 17

What are the main uses of Polysaccharides, and what are the major polysaccharides?

Answer 17

Polysaccharides are mainly used as an energy store and as
structural components of cells.
The major polysaccharides are starch and cellulose in
plants, and glycogen in animals.

Question 18

State Structures and Properties of Starch. (9)

Answer 18

Structure and properties of starch
 a-glucose polymer
 mixture of amylose and amylopectin
 joined by 1,4 and 1,6 glycosidic bonds
 insoluble storage product in plants
 energy store
 compact
 no osmotic effect
 can be rapidly hydrolysed into sugars
 source of organic carbon for synthesis of other
substances

Question 19

State information about Amylose (4).

Answer 19

Amylose:
 Straight chain molecule
 20% in starch
 Composed of glucose joined by 1,4-glycosidic bonds
 Spiral shape

Question 20

State information about Amylopectin(4).

Answer 20

Amylopectin:
 Branched molecule
 80% in starch
 Composed of glucose joined by 1,4-glycosidic bonds and 1,6
glycosidic bonds
 The 1,6-glycosidic bonds create the branche

Question 21

State using information about Starch why foods containing it are great for athletes.

Answer 21

 The combination of amylose and amylopectin in starch explain why
starchy, carbohydrate-rich foods are good for athetes doing sport.
 The amylopectin releases glucose for respiration very quickly. It is
a branched molecule so it can be hydrolysed from every branch.
 Amylose releases glycose slowly over a longer period, giving
sustained energy to the athlete.

Question 22

How does the differences of Structure of Glycogen and Starch indicate the higher metabolic requirements of animals compared to plants.

Answer 22

Glycogen is less dense and more soluble than starch, and is
broken down more rapidly. This indicates the higher
metabolic requirements of animals compared with plants

Question 23

State Structures and Properties of Glycogen. (9)

Answer 23

Structure and properties of glycogen
 a-glucose polymer
 joined by 1,4 and 1,6 glycosidic bonds
 branched structure
 insoluble storage product in animals
 energy store
 compact
 small granules suspended in cytoplasm of cells in
liver and muscle
 short chains – hydrolysed rapidly into sugars
 no osmotic effect