Carbohydrates

Question 1

List 3 types of monosaccharides

Answer 1

Glucose
Fructose
Mannose

Question 2

Distinguish between ketoses and aldose

Answer 2

• If the sugar has a ketone group it is called a ketose e.g. fructose
• If the sugar has an aldehyde group it is called an aldose e.g. glucose

Question 3

List 3 types of disaccharide

Answer 3

Sucrose- sugar beet
Lactose - milk
Maltose - plants

Question 4

List 3 types of glucans

Answer 4

Starch
Cellulose
Glycogen

Question 5

Starch

Answer 5

Carbohydrate reserve found in plant tissue
Consists of * Amylose (Alpha 1-4 linkages)
* Amylopectin (Alpha 1-4 + Alpha 1-6 linkages)
Enzymes that break down starch:
Alpha amylase- Splits Alpha 1-4 bonds
Beta amylase - Hydrolyses Alpha 1-6 bonds
Amyloglucosidase - Hydrolyses both Alpha 1-4 and Alpha 1-6 bonds, at different rates.

Question 6

Glycogen

Answer 6

A reserve carbohydrate in animals, mainly stored in the liver.
- Glucose is the basic building block.
- Similar in structure to starch but is more branched.
Consists of * Amylose (Alpha 1-4 linkages)
* Amylopectin (Alpha 1-4 + Alpha 1-6 linkages)
Enzymes that break down starch:
Alpha amylase- Splits Alpha 1-4 bonds
Beta amylase - Hydrolyses Alpha 1-6 bonds
Amyloglucosidase - Hydrolyses both Alpha 1-4 and Alpha 1-6 bonds, at different rates.

Question 7

Modified Starch - Substitution

Answer 7

Involves etherification or esterification of a small number of hydroxyl groups.
Reduces retrogradation
Lowers gelatinisation temp.
Increases viscosity

Question 8

Modified Starch- Cross Linking

Answer 8

The introduction of linkages between the chains of amylose and amylopectin.
Increases gelatinisation temp.
Inhibits gel formation
Controls viscosity

Question 9

Dietry Fibre

Answer 9

Are not broken down in the small intestines by digestive enzymes
- Includes cellulose and resistant starch.

Question 10

Glycolysis

Answer 10

The breakdown of glucose

Question 11

Gluconeogenesis

Answer 11

The conversion of all non-carbohydrates to glucose.

Question 12

Glycogenolysis

Answer 12

The pathway in which glycogen stores are converted to glucose.

Question 13

Glycogenesis

Answer 13

The synthesis of glycogen from glucose

Question 14

Lipogenesis

Answer 14

Carbohydrates are converted to fat

Question 15

Glycemic Index

Answer 15

A measure of the power of foods to raise blood sugar levels after being eaten.
High GI foods contain rapidly digested carbohydrates which produce a large rapid rise and fall in blood sugar levels.
Low GI foods contain slowly digested carbohydrates which produces a gradual low rise in blood sugar levels.

Question 16

Health problems associated with carbohydrates in the diet

Answer 16

Energy balance and obesity
Diabetes
Tooth Decay
Lactose Intolerance