Food And Diet

Question 1

What is food needed for?

Answer 1

A source of energy and to provide material for growth

Question 2

Give the function and sources of sugar

Answer 2

To provide energy

Fruit, honey, milk, soft drinks

Question 3

Give the function and sources of starch

Answer 3

To provide energy

Potatoes, pasta, bread

Question 4

Give the function and sources of cellulose (fibre)

Answer 4

Helps prevent constipation

Green vegetables and cereal

Question 5

Give the function and sources of protein

Answer 5

For growth and repair of cells, to make muscle and hair

Lean meat, egg white, soya, nuts, fish

Question 6

Give the function and sources of fats

Answer 6

To provide and store energy
Insulation

Butter, milk, cheese, oils

Question 7

Give the functions and sources of Vitamin C

Answer 7

For healthy skin and gums
Prevent scurvy

Citrus fruits

Question 8

Give the functions and sources of Vitamin D

Answer 8

To build strong bones and teeth
Prevent rickets

Cheese, milk, yoghurts

Question 9

Give the functions and sources of iron

Answer 9

Needed to make red blood cells
Prevent anaemia

Red meat, liver, cabbage

Question 10

Give the functions and sources of calcium

Answer 10

For healthy bones and teeth

Milk, cheese, tinned salmon

Question 11

How do you test for the presence of starch?

Answer 11

1. Put 2 cm3 of starch solution in one test tube
2. Put the same volume of water into another test tube
3. Add iodine solution to each test tube
4. Note any colour changes
5. Iodine is blue when starch is present and brown/yellow when starch is not present

Question 12

How do you test for the presence of a reducing sugar (glucose)?

Answer 12

1. Put water and Benedict’s Solution into one test tube and glucose solution and Benedict’s solution into another.
2. Put both into a water bath of 100 degrees Celsius
3. Record any colour changes
4. Benedict’s solution turns brick-red in the presence of a reducing sugar

Question 13

How do you test for protein?

Answer 13

1. Put water and sodium hydroxide solution into one test tube and milk and sodium hydroxide solution into another test tube.
2. Put copper sulfate solution into both
3. Note any colour changes
4. Copper sulfate turns a purple/violet in the presence of protein

Question 14

How do you test for the presence of fats?

Answer 14

1. Rub butter on one piece of brown paper and put water on the other brown paper
2. Allow both pieces of paper to dry
3. Hold each piece up to light and compare the amount of light that passes through
4. The butter turns the paper translucent showing fat is present

Question 15

How do you investigate the conversion of chemical energy in food into heat energy?

Answer 15

1. Put 20 cm3 of water in a test tube in a retort stand
2. Record the water temperature using a thermometer
3. Stick a cracker on a mounted needle
4. Hold the cracker to a Bunsen burner until it ignites
5. Hold the burning cracker under the test tube
6. When the cracker burns out record the water temperature again
7. Compare the temperatures
8. The rise in water temperature shows the chemical energy in the cream cracker has changed to heat energy. Food contains energy