Chapter 2: carbohydrates

Question 1

What is a carbohydrate molecules made up of?

Answer 1

A carbohydrate molecule is made up:
• carbon (C)
• hydrogen (H)
• oxygen (O)

• In plants, glucose is formed when carbon dioxide and water react during
photosynthesis in the presence of chlorophyll and sunlight.

Question 2

What are the end products of carbohydrates?

Answer 2

End products are glucose, fructose & galactose.

Question 3

What are monosaccharides?

Answer 3

• simplest form of sugar molecules
• known as single sugar
• dissolve easily in water to form colourless, sweet solutions
• types:
— glucose
— fructose
— galactose

Question 4

What are Disaccharides?

Answer 4

known as double sugars

• made up of two monosaccharide molecules
• white crystalline solids which are sweet and water-soluble
• types:

— sucrose
— lactose
— maltose

Question 5

What are Polysaccharides?

Answer 5

complex carbohydrates which are made up of many monosaccharide
molecules
• not sweet, not water-soluble
• types:
— starch
— cellulose (substances in cell walls of plants)
— pectin (soluble dietary fibre)
— glycogen

Question 6

What is fructose? (Monnosaccharides)

Answer 6

Fructose or fruit sugar is the sweetest natural sugar. It can be found in honey, fruit and certain vegetables (eg cabbage and french beans)

Question 7

What is galactose?(Monnosaccharide)

Answer 7

galactose does not exist alone in food.

It bonds with glucose to form lactose, a disaccharide found in milk

Question 8

What is glucose?(Monosaccharide)

Answer 8

Glucose is the most important monnosaccharide as it serves as a main source of energy.
Fruit, certain vegetables and honey are good sources of glucose

Question 9

What is lactose? (Disaccharide)

Answer 9

A molecule of lactose consist of a glucose molecule bonded to a galactose molecule. Lactose is found naturally in dairy milk.

Question 10

What is Maltose? (Disaccharide)

Answer 10

A molecule of maltose consist of two bonded glucose molecules. Maltose is found naturally in sugar molasses, germinating barley and cooked sweet potato

Question 11

What is sucrose? (Disaccharide)

Answer 11

A molecule of sucrose consist of a glucose molecule bonded to a fructose molecule.
Sucrose is found naturally in sugar cane, honey, sugar beet, fruit and certain vegetables (eg cabbage and carrot)

Question 12

What is starch? (Polysaccharide)

Answer 12

Starch consists of hundreds of gluctose molecules joined together into a chain-like molecular structure. It is abundant in cereals (eg white rice) and tubers (eg potato)

Question 13

What is Cellulose? (Polysaccharide)

Answer 13

Cellulose is an insoluble component fo cell walls that provides support to plants. Fruit (eg apple and orange), vegetables (eg carrot and chye sim) whole grains (eg brownrice) and beans (eg red beans) are good sourvces of cellulose

Question 14

What is Pectin? (Polysaccharide)

Answer 14

Pectin is a soluble component found in the cell walls of certain plants. Apple, apricot citrus fruit (eg lemon and grapefruit) and plum are good sources of pectin.

Question 15

What are examples of sources of simple carbohydrates?

Answer 15

Simple carbohydrates are food which is naturally rich is simple sugars - gluctose, fructose, lactose and maltose.

Question 16

What are examples of sources of complex carbohydrates?

Answer 16

complex carbohydrates are food that are high in polysaccharides - starch, cellulose and pectin.
Starchy vegetables, cereals, fruit, pulses, proccessed food.

Question 17

What are the functions of carbohydrates>

Answer 17

1. Provides a source of energy

2. Aids the digestion of food

Question 18

Explain the first function of carbohydrates?

Answer 18

• Carbohydrates which are consumed are
broken down into glucose to provide energy.
• Glucose which is not needed immediately is
converted into glycogen (a polysaccharide
stored in the muscles & liver in limited
amounts).
• Glycogen acts as short-term energy reserve in
the body when the blood is low in glucose.

Question 19

Explain the second function of carbohydrates?

Answer 19

• A type of carbohydrates - Non-starch polysaccharides (NSP) or dietary fibre helps to
eliminate waste materials from our body and prevent constipation.

Question 20

What are the Benefits of Non-Starch Polysaccharides (NSP)?

Answer 20

• more nutrients such as:
— B-group vitamins
— vitamin E
— iron
— magnesium
• good source of insoluble dietary fibre
• lower Glycemic Index (GI) compared to refined food — food with high GI causes the blood
sugar level to rise

Question 21

What are some ways to reduce sugar intake?

Answer 21

• Replace sweetened drinks e.g. soda and coke with plain water
• Choose fruit juices without added sugar.
• Reduce sugar in cake recipes (& bubble tea!)
• Choose food labelled as ‘no added sugar’ or ‘unsweetened’
,
‘less’ or

‘reduced sugar’
,
‘low in sugar’ or ‘sugar free’.

• Reduce spreads such as jam, kaya or marmalade on bread.
• Reduce intake of glazed doughnuts, chocolate, ice-cream and
candies.

Question 22

What are the Effects of insufficient

carbohydrate intake?

Answer 22

Disruptions to our
normal body
functions

Extreme
tiredness

Loss of
concentration

Weight loss
(in the long run)

Question 23

What are the effects of excessive

carbohydrate intake?

Answer 23

Tooth decay and
gum diseases Diabetes
mellitus
Weight
gain