Q8. Peter burns a piece of crispbread to find out how much energy is stored in it. Energy from the burning crispbread raises the temperature of the water in the test-tube.

(a) Describe one way Peter has arranged the apparatus so that he is working safely.

any one from

• the test-tube is pointing away from him - do not accept 'the test-tube is at an angle' - so that the contents cannot spit into his face.
• he used a cork and a pin to hold the burning crispbread instead of holding the crispbread himself as he might drop it.
• the test-tube is held in a clamp instead of holding it in tongs as he might drop it.
• the apparatus is away from the edge of the bench so it cannot be accidentally knocked.
• the apparatus is arranged over the base of the stand for stability so it will not easily tip over.

Do not accept 'he is wearing goggles' - He is! ...but the question asks about the apparatus arrangement!

Note that there are two mark for one safty point. That means that you do not have to just name the safety point, but you need to expand on why it improves safety to get the additional mark.

Always look carefully at mark allocation. It gives you a clue as to how much detail is required.

2 marks

(b) Peter wants to find out if potato crisps contain as much energy as crispbread. He does the experiment again using a piece of potato crisp. Suggest two things he must do to make the experiment a fair test.

any two from

• He must use the same volume of water in the test tube.
• He must use the same mass or weight of crisp accept 'use the same mass of food.' Do not accept 'use the same amount of food' I would recommend that you avoid using the word 'amount' as it is very vague. It can mean volume or mass.
• The crisp must be the same distance from the test tube as the crispbread was in the previous experiment.
• He must start with water at the same temperature as in the previous experiment.
• He should shield both experiments from draughts.

1 mark

(c) The table shows some of the nutritional information from a packet of crispbread and a packet of potato crisps.

	energy/kJ	protein/g	carbohydrate/g	fat/g	fibre/g
100g of crispbread	1455	11.6	58.1	7.3	14.7
100g of potato crisps	2072	5.8	57.9	28.7	4.3

Peter burns 1.0 g of potato crisp instead of 1.0 g of crispbread in a similar experiment. What result will he get when he burns the potato crisp?

A	The change in the temperature of the water will be greater.
B	The change in the temperature of the water will be the same.
C	The change in the temperature of the water will be smaller.
D	There will be no change in the temperature of the water.

1 mark

(d)

(i) Fibre contains energy. Explain why this energy can not be used by the human body.

Fibre cannot be digested. Accept 'it is not absorbed by the body' or 'it does not get broken down in the digestive system'. Do not accept 'it is insoluble.'

1 mark

(ii) Use the table in part (b) to give two reasons for choosing crispbread rather than potato crisps as part of a balanced diet.

any two from

• it contains less fat
• 'it is less fattening' or 'it contains less energy'
• it contains more fibre
• it contains more protein

do not accept 'more carbohydrate'

2 marks

(e) Crispbread does not contain vitamin C. Which of the foods in the list below is the best source of vitamin C?

• CHEESE
• EGGS
• FISH
• ORANGES

1 mark

Maximum 8 marks