AQA GCSE Biology Biology Paper 2 (Foundation), June 2025: Question 6
8 marks · Low Demand difficulty · Short Answer
Answer questions about a freshwater food web, including identifying energy sources, trophic levels, pyramids of biomass, percentage biomass transfer, and tallying sample data.
Practise this questionQuestion
Question text
06 Different species in a habitat may depend on each other for food.
Several food chains may be linked together to form a food web.
Figure 10 shows a food web in a lake.
Figure 10
06.1 Most organisms in the food web get their energy by eating other organisms.
Where does the pondweed get energy from?
[1 mark]
Tick ( ) one box.
Carbon dioxide
Mineral ions
Sunlight
Water 27
06.2 Name one organism from Figure 10 that is a primary consumer.
[1 mark]
06.3 There are four trophic levels in Figure 10.
Which is the correct pyramid of biomass for the food web in Figure 10?
[1 mark]
Tick ( ) one box.
06.4 One of the food chains in Figure 10 is:
10% of the biomass in each trophic level is transferred to the next trophic level.
What percentage of the biomass in the algae is transferred to the fish?
[1 mark]
Tick ( ) one box.
10% 1% 28 0.1%
06.5 What are two ways that energy is lost from organisms in the food chain?
[2 marks]
Tick ( ) two boxes.
Diffusion
Faeces
Movement
Osmosis
Photosynthesis
06.6 Scientists counted the number of fish, snails and worms in a sample taken from
the lake.
Table 3 shows the results.
Table 3
Number of organisms
Tally
in the sample
Fish
Snails
Worms
Complete Table 3.
[2 marks]
Mark scheme
Show the mark scheme
Question 6
AO /
Question Answers Extra information Mark
Spec. Ref.
06.1 sunlight 1 AO1
4.7.4.3
AO /
Spec. Ref.
06.2 worm 1 AO3
or 4.7.4.1
snail
AO /
Spec. Ref.
06.3 1 AO3
4.7.4.2
4.7.4.3
AO /
Spec. Ref.
06.4 1% 1 AO2
4.7.4.3
AO /
Spec. Ref.
06.5 faeces 1 AO1
4.7.4.3
movement 1 4.7.5.2
AO /
Spec. Ref.
06.6 all correct = 2 marks 2 AO2
1 or 2 correct = 1 mark 4.7.2.1
(fish) 3
(snails) 12
(worms) 23
Total Question 6 8 17
How to answer it
Feeding Relationships, Biomass & Energy Transfers
This question assesses core ecological principles from AQA GCSE Biology:
- Producers & Energy Sources: Recall that plants convert light energy into chemical energy via photosynthesis.
- Trophic Classifications: Identifying primary consumers from a food web.
- Pyramids of Biomass: Understanding the characteristic pyramid shape representing dry mass across trophic levels.
- Energy Transfer Calculations: Calculating cumulative biomass loss across multiple feeding stages.
- Biological Energy Losses: Identifying metabolic and physiological pathways where energy is lost between trophic levels.
- Data Handling: Converting tallies into numerical values.
Energy Source for Producers
Identifying where aquatic plants obtain their initial energy
✅ Correct Answer
Sunlight [1 mark]
💡 Key Knowledge
Pondweed is a photosynthetic plant (a producer). Producers absorb light energy from the Sun and convert it into chemical energy stored in glucose.
❌ Common Errors
Confusing matter with energy: Water, carbon dioxide, and minerals provide raw chemical elements, but none of them supply the energy input.
Primary Consumers
Identifying organisms at trophic level 2 from a food web
✅ Correct Answer
Either of the following:
- worm [1 mark]
- snail [1 mark]
💡 Key Knowledge
Primary consumers are herbivores that eat producers. Looking at Figure 10, both worms and snails have arrows pointing directly to them from algae and pondweed.
🧠 Exam Technique
Follow the direction of the arrow. Arrows indicate the flow of biomass/energy from prey to predator. Algae/pondweed → worm/snail.
Pyramids of Biomass
Recognising the structure of a biomass pyramid
✅ Correct Answer
The first box (the pyramid that steps inwards symmetrically at each higher level) [1 mark].
Structure: Wide base at the bottom, progressively narrower tiers towards the top.
💡 Key Knowledge
Unlike pyramids of numbers (which can be inverted), a pyramid of biomass is ALWAYS a true pyramid shape. Biomass is lost at every trophic stage, so each tier must be narrower than the one below it.
❌ Common Errors
Selecting the inverted or irregular diagrams. Students sometimes confuse biomass pyramids with number pyramids (e.g. 1 oak tree feeding thousands of caterpillars).
Calculating Biomass Transfer
Determining percentage transfer over two feeding steps
✅ Correct Answer
1% [1 mark]
📐 Step-by-Step Calculation
- Identify starting baseline: Algae start with 100% of available biomass.
- Step 1 (Algae → Worm): 10% is transferred:
100% × 0.10 = 10% - Step 2 (Worm → Fish): 10% of the worm's biomass is transferred to the fish:
10% × 0.10 = 1%
❌ Common Errors
Ticking 10%. 10% is transferred at each stage, but the question asks how much of the original biomass in the algae reaches the fish (two stages).
Energy Loss in Food Chains
Identifying physiological processes that waste energy
✅ Correct Answers (Tick two)
- Faeces [1 mark]
- Movement [1 mark]
💡 Key Knowledge
Energy is lost at trophic levels through:
- Respiration: Fuels processes like movement and maintaining body temperature; energy is ultimately transferred to the surroundings as heat.
- Egestion: Undigested waste material passed out as faeces.
- Excretion: Metabolic waste such as urea in urine.
❌ Common Errors
Selecting Diffusion or Osmosis. While these are biological transport mechanisms, they are passive processes that do not represent major energy loss pathways in food chains.
Completing the Tally Chart
Accurately counting biological survey tallies
| Organism | Tally | Number of organisms in the sample |
|---|---|---|
| Fish | ||| | 3 |
| Snails | |||| |||| || | 12 |
| Worms | |||| |||| |||| |||| ||| | 23 |
Mark Scheme Criteria
• All 3 correct = 2 marks
• 1 or 2 correct = 1 mark
🧠 Exam Technique
A crossed-through tally group always represents 5. Count in multiples of 5 before adding the individual lines:
- Snails: 5 + 5 + 2 = 12
- Worms: (4 × 5) + 3 = 20 + 3 = 23
Topics
Biology · B7: Ecology
Question and mark scheme from the AQA GCSE Biology examination, Biology Paper 2 (Foundation), June 2025. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.