AQA GCSE Combined Science: Trilogy Chemistry Paper 2 (Foundation), 2022: Question 2

8 marks · Standard Demand difficulty · Short Answer

Identify biological and chemical processes related to fossil fuels and analyze UK electricity generation trends from a stacked bar chart.

Practise this question

Question

The image shows a multi-part GCSE science question about fuels. Question 02.1 asks for the name of the process in leaves that uses carbon dioxide. Question 02.2 is a multiple-choice question asking how coal is formed, with options: burned, compressed, or melted. Questions 02.3 and 02.4 ask for the name of the gas produced when sulfur burns and two problems it causes. Question 02.5 presents Figure 4, a stacked bar chart showing the relative amount of electricity generated in the UK from 2012 to 2018 from four sources: Fossil fuels, Renewable fuels, Nuclear fuel, and Other.
Question text

02 This question is about fuels.

Coal deposits were formed from the remains of trees.

02.1 Name the process in the leaves of trees that uses carbon dioxide.

[1 mark]

02.2 How is coal formed after trees die?

[1 mark]

Tick ( ) one box.

The trees are burned.

The trees are compressed.

The trees are melted.

Coal contains small amounts of sulfur.

02.3 Name the gas produced when sulfur burns in oxygen.

[1 mark]

02.4 Give two problems caused by the gas produced when sulfur burns in oxygen.

[2 marks]

02.5 Figure 4 shows the relative amount of electricity generated from different fuel sources

in the UK from 2012 to 2018.

Figure 4

Describe what happens to the amounts of fuels used to generate electricity

in the UK from 2012 to 2018.

[3 marks]

Mark scheme

Show the mark scheme The mark scheme table lists the correct answers for questions 02.1 to 02.5. 02.1 is 'photosynthesis'. 02.2 is 'the trees are compressed'. 02.3 is 'sulfur dioxide' or 'SO2'. 02.4 lists 'acid rain' and 'respiratory problems' as two separate marking points. 02.5 awards up to 3 marks for describing trends: fossil fuels decreased, renewable fuels increased, and nuclear or other fuels remained constant between 2012 and 2018.

Question 2

AO /

Question Answers Extra information Mark

Spec. Ref.

02.1 photosynthesis 1 AO1

5.9.1.4

AO /

Spec. Ref.

02.2 the trees are compressed 1 AO1

5.9.1.4

AO /

Spec. Ref.

02.3 sulfur dioxide allow SO2 1 AO1

5.9.3.1

AO /

Spec. Ref.

02.4 allow ecf from question 02.3 AO1

5.9.3.2

acid rain allow specified damage caused 1

by acid rain

respiratory problems allow named respiratory 1

problem

AO /

Spec. Ref.

02.5 any three from: 3 AO2

5.10.1.1

(from 2012 to 2018)

• fossil fuels decreased 9

• renewable fuels increased

• nuclear fuel remain constant

• other (sources) remain

constant

Total Question 2 8

How to answer it

Fossil Fuels, Pollutants, and Energy Trends

What this question tests

This question assesses your understanding of how fossil fuels are formed, the environmental impact of burning impurities like sulfur, and your ability to describe trends in national energy usage from a bar chart.

Part 02.1 & 02.2

Coal Formation

The origins of fossil fuels

Correct Answers

  • 02.1: Photosynthesis
  • 02.2: The trees are compressed

Key Knowledge

Coal is formed from trees and ferns that grew in vast swamps millions of years ago. When they died, they were buried by sediment, preventing decay. Over time, high pressure and heat compressed the remains into coal.

Exam Technique

For 02.1, the question asks for the process that uses carbon dioxide. Remember: Photosynthesis takes CO₂ in, while Respiration and Combustion release it back out.

Part 02.3 & 02.4

Sulfur Impurities

Pollution and its effects

Correct Answers

  • 02.3: Sulfur dioxide (or SO₂)
  • 02.4: Acid rain AND Respiratory problems (e.g., asthma)

Common Errors

  • Confusing sulfur dioxide with carbon dioxide (global warming).
  • Writing "pollution" as a problem—this is too vague! You must name a specific environmental or health effect.

Examiner Insight

If you get the gas wrong in 02.3, you can still get marks in 02.4 if the problems you list match the gas you named. This is called Error Carried Forward (ecf). However, it's always best to learn the specific link: Sulfur → Acid Rain.

Part 02.5

Interpreting Data

UK Electricity Generation Trends

Correct Answers (Any 3)

  • Fossil fuels decreased
  • Renewable fuels increased
  • Nuclear fuel remained constant (the same)
  • "Other" sources remained constant

How to score 3/3

When "describing" a chart like Figure 4:

  1. Look at the start (2012) and the end (2018).
  2. Identify which segments got bigger, smaller, or stayed the same.
  3. Use comparative language like "increased" or "decreased."

Visual Guide to Figure 4

If you were to redraw this trend as a simple line graph, you would see:

  • Fossil Fuels: A downward sloping line.
  • Renewables: An upward sloping line.
  • Nuclear: A flat, horizontal line.

Common Pitfalls

Don't try to explain why this is happening (e.g., "because of global warming"). The question only asks you to describe what happens to the amounts based on the provided image.

Topics

Biology · Chemistry · Physics · B4: Bioenergetics · C9: Chemistry of the Atmosphere · C10: Using Resources · P1: Energy

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Chemistry Paper 2 (Foundation), 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.