AQA GCSE Combined Science: Trilogy Biology Paper 2 (Higher), 2022: Question 6

✅ Correct answers

• Domain: eukaryota / eukaryote
• Kingdom: animalia / animal
• Phylum: chordata
• Family: ursidae

💡 Key knowledge

• The classification sequence is: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
• Ursus maritimus is the binomial name: Ursus = genus, maritimus = species.
• Polar bears are mammals, so they are in the animal kingdom and chordate phylum.

🧠 Exam technique

• Use the given clues in the table to work out the missing group names.
• Case and italics are not important here — the mark scheme says to ignore them.
• There are 2 marks for all 4 correct; 1 mark for 2 or 3 correct.

❌ Common errors

• Writing phylum or family in the name column instead of the taxon name.
• Mixing up class and order.
• Forgetting that the domain is eukaryote.

📐 Calculations — step by step

1. Choose two points on the trend line, not random dots.
2. From the graph, suitable readings are about 7.75 million km² in 1985 and 4.32 million km² in 2017.
3. Find the change in area: 7.75 - 4.32 = 3.43 million km².
4. Find the time interval: 2017 - 1985 = 32 years.
5. Calculate the rate: 3.43 ÷ 32 = 0.1071875 million km² per year.
6. Round appropriately: 0.11 million km² per year, or 0.1 million km² per year if using the graph estimate given in the mark scheme.

✅ Correct answer

• Rate of loss = 0.1 million square kilometres per year
• Accept values close to this if calculated from correct graph readings.

💡 Key knowledge

• Rate = change in y ÷ change in x.
• Here, y is area of sea ice and x is time.
• The unit must be written as million square kilometres per year.

❌ Common errors

• Using two random dots instead of the trend line.
• Subtracting the years in the wrong order and getting a negative rate.
• Forgetting the units or writing only 0.1 with no unit.
• Giving the area loss without dividing by time.

✅ Correct answers

Any two of the following:

• In autumn there are fewer seals left on the ice / most seals are in the sea.
• Seals are adults or older, so they swim faster.
• There is more competition between polar bears.

💡 Key knowledge

• In spring, seals are on the ice raising pups, so they are easier to find.
• By autumn, the ice area is at its lowest, so hunting opportunities are reduced.
• Polar bears may need to travel further, which uses more energy.

🧠 Exam technique

• Give two separate, clear reasons for 2 marks.
• Write the answer as cause → effect.
• Use wording from the mark scheme ideas, but not necessarily exact phrases.

❌ Common errors

• Saying only that “there are seals in the sea” without explaining why that makes catching them harder.
• Giving vague answers such as “it is colder” or “they are hungry” without linking to hunting success.
• Repeating the same idea twice.

💡 Key knowledge

• Global warming is melting sea ice.
• Less sea ice means less habitat and less hunting area.
• Polar bears may need to swim longer distances to find seals, wasting energy.
• Less food means they may build up less fat, so fewer survive winter.
• Decreased mass/height may reduce hunting ability and strength.
• Hunting bans or reduced hunting could help the population recover in some areas.
• Reducing carbon dioxide emissions could slow future habitat loss.

✅ What a strong answer includes

• A clear judgement: the population will likely decrease unless conditions improve.
• At least two reasons for decrease.
• At least one reason why numbers could increase or be maintained.
• A linked conclusion showing which effect is more likely overall.

🧠 Exam technique

• For Level 2, you must consider both decrease and increase/maintenance.
• Make a judgement such as: “Overall, the population is likely to decrease because…”
• Support each point with a chain of reasoning, not just a list of facts.
• Good evaluation answers are balanced and then reach a final conclusion.

❌ Common errors

• Only describing sea ice loss without linking it to polar bear survival.
• Talking about one side only, for example only why the population could fall.
• Not making a conclusion.
• Writing “global warming is bad” without explaining the biological effect.

💡 Top-level responses

• Used precise scientific terms like habitat, energy, fat stores, and competition.
• Gave a balanced evaluation in 06.4.
• Showed calculation steps clearly in 06.2.

❌ Where marks were lost

• Misreading the graph and using values from a single point instead of the trend line.
• Not stating the unit for the rate.
• Giving incomplete explanations, especially in 06.3 and 06.4.