AQA GCSE Combined Science: Trilogy Biology Paper 1 (Higher), 2024: Question 1

13 marks · Standard Demand difficulty · Extended Answer

Describe food tests for sugar and protein and explain how protein and fat are digested in the human digestive system.

Practise this question

Question

Question text

01 Drinks contain different substances.

A drinks company claims that a drink contains sugar, protein and fat.

01.1 Glucose and fructose are different sugars.

Fructose has a much sweeter taste than glucose.

Suggest two reasons why the drinks company uses fructose in the drink rather than

using glucose.

Do not refer to sweetness in your answer.

[2 marks]

01.2 Describe how a student could test the drink for sugar.

Give the colour of a positive result.

[3 marks]

Test

Colour of positive result 3

01.3 Describe how a student could test the drink for protein.

Give the colour of a positive result.

[2 marks]

Test

*02* 4

Colour of positive result

01.4 The human digestive system breaks down protein and fat in the drink.

Describe how protein and fat are digested.

You should include:

• the enzymes involved

• where the enzymes are produced.

[6 marks]

Mark scheme

Show the mark scheme

Question 1

AO /

Question Answers Extra information Mark

Spec. Ref.

01.1 any two from: 2 AO3

• less (fructose / sugar) needed ignore fructose is sweeter than 4.2.2.1

glucose

• cheaper to produce / buy the allow less (sugar) tax

drink allow more profit

ignore cheaper unqualified

• less energy in the drink (so allow less calories / J / KJ in the

people are more likely to buy drink

it)

allow less (fructose / sugar)

needed so would be cheaper for

2 marks

AO /

Spec. Ref.

01.2 add Benedict’s (reagent / 1 AO1

solution) 4.2.2.1

RPA3

heat reagent / solution allow appropriate method of 1

heating

if a temperature is given, must

be at least 60 °C

ignore warm

green / yellow / orange / brown / ignore starting colour 1

(brick) red

AO /

Spec. Ref.

01.3 add Biuret (reagent / solution) allow add Biuret A and Biuret B 1 AO1

4.2.2.1

allow add potassium / sodium RPA3

hydroxide solution and copper

sulfate solution

mauve / purple / lilac / pink- ignore starting colour 1

purple – – –

AO /

Question Answers Mark

Spec. Ref

01.4 Level 2: Scientifically relevant facts, events or processes are 4‒6 AO1

identified and given in detail to form an accurate account. 4.2.2.1

Level 1: Facts, events or processes are identified and simply 1‒3

stated but their relevance is not clear.

No relevant content 0

Indicative content

Protein

• protease

o (protein) broken down into amino acids

o (protease) produced in the stomach

o (protease) produced in the pancreas

o (protease) produced in the small intestine

o (hydrochloric) acid provides the correct pH for protease

(in the stomach)

Fat

• lipase

o (fat) broken down into fatty acids

o (fat) broken down into glycerol

o (lipase) produced by the pancreas

o (lipase) produced by the small intestine

o bile

o (bile) produced by the liver

o (bile) released from the gall bladder

o emulsification of fats

o larger surface area for lipase

o neutralises acid to provide the correct pH for enzymes

For Level 2, answers must describe digestion of fat and protein

linked to correct type of enzyme for both

Total Question 1 13

How to answer it

Standard Demand

Food Tests and Digestion in a Drink

What this question tests

This question tests your knowledge of food tests for sugar and protein, why a company might choose one sugar over another, and how protein and fat are digested in the human digestive system. You need to name the correct reagents, give positive colours, and link enzymes to where they are produced and what they break down into.

Question 01.1

Part (a): Why use fructose instead of glucose?

2 marks

✅ Correct answers

Less fructose (or less sugar) is needed.
It could be cheaper to produce or buy the drink.
The drink could contain less energy, so it may be more attractive to customers.

Any two of these score the 2 marks.

💡 Key knowledge

You were told not to refer to sweetness.
The idea is that because fructose is sweeter, a company may use less of it.
Using less sugar can reduce cost and reduce energy content.

🧠 Exam technique

Give two separate reasons, not the same point repeated.
Make each reason practical or commercial.
Good answers explain a benefit to the company or customer.

Model answer:
1. Less fructose is needed.
2. This could make the drink cheaper to make and lower in energy.

❌ Common errors

Saying “because fructose is sweeter” on its own. The mark scheme says to ignore this.
Saying only “cheaper” without explaining why. “Cheaper to produce / buy the drink” is acceptable, but just one vague word is weak.
Repeating the same idea twice, such as “less sugar needed” and “uses a smaller amount”.

Question 01.2

Part (b): Test the drink for sugar

3 marks

✅ Correct answers

Add Benedict’s solution (or Benedict’s reagent).
Heat the mixture.
Positive result: green, yellow, orange, brown or brick-red.

1 mark for Benedict’s solution, 1 mark for heating, 1 mark for a correct positive colour.

💡 Key knowledge

Benedict’s test is for reducing sugars.
The sample must be heated.
If a temperature is given, it must be at least 60 °C.
The colour can vary depending on how much sugar is present.

🧠 Exam technique

State both the reagent and the heating step.
Then separately state the colour of a positive result.
Use the wording from required practicals because that matches mark schemes well.

Model answer:
Add Benedict’s solution to the drink and heat it in a hot water bath. A positive result is a colour change to green, yellow, orange or brick-red.

❌ Common errors

Forgetting to mention heating. This loses a mark.
Saying the result is “blue”. Blue is the starting colour, not a positive result.
Saying just “it changes colour” without naming the colour.
Writing “warm” instead of actually describing heating properly. The mark scheme says ignore warm.

Question 01.3

Part (c): Test the drink for protein

2 marks

✅ Correct answers

Add Biuret solution (or Biuret reagent).
Positive result: mauve, purple, lilac or pink-purple.

1 mark for the correct test, 1 mark for the correct positive colour.

💡 Key knowledge

Biuret test is used for proteins.
The reagent may be described as Biuret A and Biuret B.
It is also acceptable to describe adding sodium hydroxide or potassium hydroxide and copper sulfate.

🧠 Exam technique

This is a short-answer question, so be precise.
Name the reagent clearly, then give the positive colour.
Keep sugar and protein tests separate in your memory.

Model answer:
Add Biuret solution to the drink. A positive result is purple (or lilac / mauve).

❌ Common errors

Mixing this up with Benedict’s test.
Giving the wrong positive colour, such as brick-red.
Not naming the reagent at all.

Question 01.4

Part (d): How protein and fat are digested

6 marks

✅ Correct answers

Protein: Protease digests proteins into amino acids.
Protease is produced in the stomach, pancreas and small intestine.
Hydrochloric acid in the stomach provides the correct pH for protease.
Fat: Lipase digests fats into fatty acids and glycerol.
Lipase is produced by the pancreas and small intestine.
Bile is produced by the liver and released from the gall bladder into the small intestine.
Bile emulsifies fats, increasing the surface area for lipase.
Bile also neutralises stomach acid to give a better pH for enzymes in the small intestine.

To reach Level 2 (4–6 marks), the answer must describe digestion of both fat and protein and link each to the correct enzyme type.

💡 Key knowledge

Protease → protein → amino acids
Lipase → fat → fatty acids + glycerol
Bile is not an enzyme.
Bile helps fat digestion by emulsifying fat and neutralising acid.
The question specifically asked for the enzymes involved and where they are produced.

🧠 Exam technique

For 6-mark questions, organise your answer into two clear parts: protein, then fat.
For each one, include:
- the enzyme name
- where it is produced
- what it breaks the food into
Then add bile details for fat digestion to push into the top of the level.
Top answers are linked explanations, not just lists of facts.

Model 6-mark answer:
Protein is digested by protease enzymes. Protease is produced in the stomach, pancreas and small intestine. Protease breaks proteins down into amino acids. In the stomach, hydrochloric acid provides the correct pH for protease to work.

Fat is digested by lipase enzymes. Lipase is produced by the pancreas and small intestine. Lipase breaks fats down into fatty acids and glycerol. Bile is produced by the liver and released from the gall bladder into the small intestine. Bile emulsifies the fat, which increases the surface area for lipase, and it also neutralises acid to provide the correct pH for the enzymes in the small intestine.

❌ Common errors

Not mentioning both protein and fat. That limits the level.
Saying bile is an enzyme. It is not.
Forgetting what the food is broken into:
- protein → amino acids
- fat → fatty acids and glycerol
Only naming organs with no link to the enzymes they produce.
Talking generally about digestion without referring to enzyme names.

📐 Mark breakdown and level guidance

1–3 marks (Level 1): some correct facts are given, but the explanation is simple or incomplete.
4–6 marks (Level 2): accurate, relevant detail about both protein and fat digestion, with correct enzymes and where they are produced.
To get full marks, link each enzyme to its substrate and products, and include the role of acid and bile.

Quick full-answer checklist

💡 Must-know facts

Benedict’s + heat → sugar test
Positive Benedict’s colour: green / yellow / orange / brown / brick-red
Biuret → protein test
Positive Biuret colour: purple / lilac / mauve
Protease breaks protein into amino acids
Lipase breaks fat into fatty acids and glycerol
Bile is made by the liver and released from the gall bladder

🧠 Examiner insight

Students often lost marks by confusing food tests.
In the sugar test, many forgot the heating step.
In the 6-marker, stronger answers linked enzyme, organ, and digestion product together in full sentences.
The best responses also included the role of hydrochloric acid and bile.

Topics

Biology · Required Practicals · B2: Organisation · Biology Required Practicals

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Biology Paper 1 (Higher), 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.