AQA GCSE Combined Science: Trilogy Biology Paper 2 (Foundation), 2023: Question 4
12 marks · Standard Demand difficulty · Short Answer
This multi-part biology question explores the classification of salmon, food chain dynamics, the process and consequences of selective breeding for disease resistance, and the evaluation of genetically modified (GM) salmon farming.
Practise this questionQuestion
Question text
04 Salmon are fish.
A species of salmon has the binomial name Oncorhynchus keta.
04.1 Table 3 shows the classification for this species of salmon.
Complete Table 3.
Choose answers from the box.
[3 marks]
Class Domain Genus Kingdom Species
Table 3
Group Classification for salmon
Animalia
Phylum Chordata
Family Salmonidae
Oncorhynchus
16 keta
Figure 5 shows sea lice attached to the skin of a salmon.
Figure 5
Sea lice are small animals that feed on the skin and blood of salmon.
On a salmon farm, the salmon are fed with food made from soya plants.
04.2 Which food chain represents the salmon, sea lice and soya plants?
[1 mark]
Tick ( ) one box.
salmon → sea lice → soya plants
sea lice → soya plants → salmon
soya plants → salmon 17→ sea lice
04.3 What do the arrows in a food chain represent?
[1 mark]
Tick ( ) one box.
The different numbers in the food chain
The predators in the food chain
The producers in the food chain
The transfer of energy in the food chain18
Some salmon are more resistant than other salmon to sea lice infections.
Salmon farmers selectively breed salmon.
04.4 Salmon farmers select salmon that are most resistant to sea lice and breed these
salmon together.
What is the next stage in selectively breeding salmon that are resistant to sea lice?
[1 mark]
Tick ( ) one box.
Breed together the offspring that are most resistant to sea lice.
Kill any offspring that are resistant to sea lice before the lice can attach.
Remove the gene for resistance to sea lice from the selected salmon.
04.5 When is the process of selective breeding finished?
[1 mark]
Tick ( ) one box.
After one generation have produced offspring
When all offspring are resistant to sea lice
When sea lice are living on all salmon19
04.6 Salmon that do not have sea lice are more profitable for the salmon farmer.
Suggest one reason why.
[1 mark]
04.7 What is a disadvantage of selectively breeding salmon?
[1 mark]
Tick ( ) one box.
All the salmon may suffer from the same diseases.
Fewer sea lice will infect the salmon.
The salmon will have a large variety of genes.20
Other fish farmers have produced genetically modified (GM) salmon.
GM salmon grow large enough to sell in 18 months.
Non-GM salmon grow large enough to sell in 3 years.
GM salmon need 25% less food than non-GM salmon to get to the same size.
04.8 Suggest two advantages of farming GM salmon instead of farming non-GM salmon.
[2 marks]
04.9 GM salmon are often farmed a long distance from where wild, non-GM salmon live.
*19* What is an advantage of farming GM salmon a long distance from where
wild salmon live?
[1 mark]
Tick ( ) one box.
To give the GM salmon different conditions to wild salmon
To increase the genetic differences between GM salmon and wild salmon
To reduce the risk of GM salmon breeding with wild salmon
Mark scheme
Show the mark scheme
Question 4
AO /
Question Answers Mark
Spec. Ref.
04.1
Group Classification for salmon
Kingdom 1 AO2
4.6.4
Genus 1
Species 1
ignore upper case and italics
AO /
Spec. Ref.
04.2
soya plants → salmon → sea lice 1 AO2
4.7.2.1
AO /
Question Answers Extra information Mark
Spec. Ref.
04.3 the transfer of energy in the food 1 AO1
chain 4.7.2.1
AO /
Spec. Ref.
04.4 breed together the offspring that 1 AO2
are most resistant to sea lice 4.6.2.3
AO /
Spec. Ref.
04.5 when all offspring are resistant 1 AO2
to sea lice 4.6.2.3
AO /
Spec. Ref.
allow converse for salmon that
04.6 have sea lice if clearly stated
any one from: 1 AO3
• salmon grow larger 4.6.2.3
• salmon grow faster
• salmon need less food
• salmon lose less energy
• do not have to remove sea
lice
• no / less need for pesticides allow no / less need for
insecticides
• not off-putting (to consumers /
buyers)
• (salmon) more likely to be
sold / bought
• salmon less likely to be
damaged / infected
• no / less need for antibiotics / do not accept the idea of
medication antibiotics / medication killing
sea lice
ignore sea lice are not feeding
on salmon unqualified
AO /
Spec. Ref.
04.7 all the salmon may suffer from 1 AO3
the same diseases 4.6.2.3
AO /
Spec. Ref.
answers must be comparative
04.8 allow converse for non-GM
salmon if clearly stated
any two from: 2 AO3
(GM salmon) 4.6.2.4
• more profit(able) / cost- allow sell for more money /
effective revenue
• cost less to feed ignore less food unqualified
• grow faster allow can be sold sooner
allow sell twice as many (in 3
years)
allow grow bigger (in 3 years)
• do not need to be farmed /
kept as long
• feeds more people allow cheaper to buy salmon
ignore reference to sea lice
AO /
Spec. Ref.
04.9 to reduce the risk of GM salmon 1 AO3
breeding with wild salmon 4.6.2.4
Total Question 4 12
How to answer it
Classification, Breeding, and GM in Salmon Farming
What this question tests
This question assesses your ability to recall the Linnaean classification system, interpret food chains, and understand the processes, advantages, and disadvantages of both selective breeding and genetic modification (GM).
Part (a): Question 4.1
Classification Hierarchy
💡 Key Knowledge
The Linnaean system ranks organisms in this order:
- Kingdom (Animalia)
- Phylum (Chordata)
- Class
- Order
- Family (Salmonidae)
- Genus (Oncorhynchus)
- Species (keta)
🧠 Exam Technique
Use the binomial name provided in the text: Oncorhynchus keta. The first word is always the Genus and the second is the Species.
✅ Correct Answers
1. Kingdom (top row)
2. Genus (fourth row)
3. Species (bottom row)
Parts (b) & (c): Questions 4.2 & 4.3
Food Chains and Energy
✅ Correct Answers
4.2: soya plants → salmon → sea lice
4.3: The transfer of energy in the food chain
🧠 Exam Technique
In a food chain, the arrow points away from the organism being eaten and towards the consumer. It shows the direction of energy flow.
Parts (d), (e), (f) & (g): Questions 4.4 – 4.7
Selective Breeding
💡 Key Knowledge
Selective breeding involves choosing parents with desired traits, breeding them, and then choosing the best offspring to breed again over many generations.
❌ Common Errors
Students often think selective breeding is "finished" after one go. It actually takes many generations until all offspring show the desired characteristic.
✅ Correct Answers
- 4.4: Breed together the offspring that are most resistant to sea lice.
- 4.5: When all offspring are resistant to sea lice.
- 4.6: Salmon grow faster / Salmon need less food / No need for expensive pesticides.
- 4.7: All the salmon may suffer from the same diseases (due to reduced genetic variation).
Parts (h) & (i): Questions 4.8 & 4.9
Genetic Modification (GM)
🧠 Exam Technique: Using the Data
For 4.8, look at the text provided: GM salmon take 18 months to grow, while non-GM take 3 years. This is a huge clue!
✅ Correct Answers (4.8)
Any two from:
- They grow faster (reach saleable size sooner).
- They are more profitable / cost-effective.
- They cost less to feed.
✅ Correct Answer (4.9)
To reduce the risk of GM salmon breeding with wild salmon.
❌ Examiner Warning
For 4.8, do not just say "less food." You must be comparative or specific (e.g., "cost less to feed" or "need 25% less food").
Diagram Description
📐 Visualizing the Process
If asked to draw a diagram of Selective Breeding, you should show:
- A large group of salmon with varying resistance.
- Arrows pointing to the two most resistant individuals being paired.
- A second generation of offspring.
- A repeat of the selection process for the "best" of that generation.
Topics
Biology · B6: Inheritance, Variation and Evolution · B7: Ecology
Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Biology Paper 2 (Foundation), 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.