These eight questions move from reading a value to judging a plan. Write each answer on paper before opening the explanation.
The set covers the cluster on environmental sustainability. The timed practice session builder can turn it into a timed run.
Questions
Question 1 (1 mark). Dissolved oxygen in an invented pond was 7.5 mg/L on Monday and 5.0 mg/L on Friday. State the direction of change.
Answer
It decreased. The value fell from 7.5 to 5.0 mg/L, a drop of 2.5 mg/L.
Question 2 (2 marks). An invented air-quality table gives 45 on Tuesday, 52 on Wednesday and 88 on Thursday, where a higher number means worse air. State the day with the worst air and the size of the rise from Wednesday.
Answer
Thursday had the worst air, with a value of 88. The rise from Wednesday was 88 − 52 = 36.
Question 3 (2 marks). A student says “The factory caused the drop” after seeing one table of river readings taken on one day. Give one reason the claim is not supported.
Answer
One day of readings shows a difference in place or time but not its cause. The table needs evidence linking the factory, such as readings before and after it opened, to support that claim. A safer wording is “consistent with”.
Question 4 (3 marks). Explain how fertiliser washed into a lake can reduce the oxygen available to fish.
Answer
Nutrients in the fertiliser make algae grow and multiply quickly. When the algae die, bacteria decompose them and use up dissolved oxygen. Less oxygen is left for the fish.
Each link is a mark. A one-jump answer such as “fertiliser pollutes the lake” earns at most one.
Question 5 (3 marks). An invented factory chimney releases sulfur dioxide. Describe how this could reduce the growth of crops on nearby farms.
Answer
The gas dissolves in moisture in the air and forms acidic droplets. Rain carries the acid to the soil, making it more acidic. Crops take up nutrients poorly from acidic soil, so they grow badly.
Question 6 (3 marks). A town produces 50 tonnes of waste a day. Plan X diverts 30% through recycling and composting. Calculate the waste sent to landfill each day.
Answer
Diverted: 0.30 × 50 = 15 tonnes. To landfill: 50 − 15 = 35 tonnes a day.
This assumes the town still produces 50 tonnes a day and the 30% diversion is achieved.
Question 7 (4 marks). Compare landfill and incineration on two criteria.
Answer
Land needed: landfill needs a large area that fills up, but incineration needs little land because it reduces the waste volume. Energy: incineration can recover heat to generate electricity, but landfill recovers nothing from the waste.
A conclusion is optional here. Naming the criterion in each sentence is what earns the marks.
Question 8 (5 marks). An invented school proposes a tank that collects 6 000 litres of rainwater in a month. The school’s garden needs 10 000 litres. Evaluate the proposal.
Answer
Aim: reduce tap water use for the garden. Evidence for: 6 000 ÷ 10 000 = 0.6, so the tank covers 60% of the need. Limit: the 6 000 litres assumes an average rainfall month, and a dry month would collect less. Cost was not given, so it cannot be judged.
Conclusion: worthwhile for partial cover if rainfall is reliable, with tap water kept as a backup for the remaining 40%.
If you got these wrong
Missed questions 1 to 3: revisit interpreting environmental indicator data. Missed 4 and 5: go to explaining pollution pathways.
Missed 6 and 7: read comparing waste-management approaches. Missed 8: work through evaluating a sustainability proposal.
Log each error in the mistake log and paper-error review. For a teacher to mark your wording, see online one-to-one Science tuition.