This set mixes the five skills in ecosystems and environmental change: the climate, vegetation and soil chain, food-web and land-cover data, disturbance chains, conservation evidence and fair description. All numbers are invented for practice.
Work in order from easier to harder, with a calculator and a pencil. Cover the answers until you have written your own. The statistics and distribution explorer and the food-web and energy-flow explorer help you check working, and the mistake log is the place to record slips.
Questions
Q1 (easy). Give the order of the chain linking these: litter, climate, vegetation, soil, decomposition.
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Climate, vegetation, litter, decomposition, soil. Climate decides what grows, the vegetation drops litter, decomposers break it down, and the products form the soil.
Q2 (easy). Place A has 2,000 mm of rain a year and Place B has 500 mm. How many times more rain does A have?
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2,000 ÷ 500 = 4 times. Check: 500 × 4 = 2,000.
Q3 (easy). Explain why decomposition is slow in a cold place.
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Low temperature slows the activity of fungi and bacteria, so dead material breaks down slowly. Litter can build up and fewer nutrients are released each year.
Q4 (medium). A food chain has 12,000 kJ in producers. If 10% is passed on at each level, how much energy is in the secondary consumers?
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Primary: 10% of 12,000 = 1,200 kJ. Secondary: 10% of 1,200 = 120 kJ. Check: 12,000 × 0.1 × 0.1 = 120.
Q5 (medium). Mangrove cover in a bay was 800 km² in the first survey and 680 km² in the second. Give the change and the percentage change.
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Change = 680 − 800 = −120 km². Percentage change = −120 ÷ 800 × 100 = −15%. Check: 15% of 800 is 120.
Q6 (medium). In a region of 4,000 km², grassland covered 1,000 km² in Year 1 and 800 km² in Year 10. Give the fall in share in percentage points, and the percentage change of the grassland itself.
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Share in Year 1: 1,000 ÷ 4,000 = 25%. Share in Year 10: 800 ÷ 4,000 = 20%. Fall = 5 percentage points.
Percentage change of the grassland: −200 ÷ 1,000 × 100 = −20%. The two numbers differ because they use different totals.
Q7 (medium). Explain, using a causal chain, how a severe drought could reduce the number of insect-eating birds in a woodland.
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Drought leaves the soil dry, so plants wilt or die. Fewer plants mean less food and shelter for insects, so insect numbers fall. Insect-eating birds then have less food, so fewer survive and breed, and bird numbers fall. Each step uses a reason.
Q8 (harder). A project protects a lizard species. Counts were 60 in Year 1 and 69 in Year 4 in the protected area, and 55 and 58 in an unprotected area. Calculate both percentage changes and write a cautious evaluation.
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Protected: change +9, 9 ÷ 60 × 100 = +15%. Unprotected: change +3, 3 ÷ 55 × 100 = +5.5% (to 1 decimal place). Check: 5.5% of 55 is about 3.
Evaluation: the protected area rose by about 9.5 percentage points more, which suggests the protection may have helped. The period is short, there is one pair of sites, and the numbers are small, so a few animals could change the result. The evidence is consistent with a benefit but does not prove it.
Q9 (harder). In a survey, 18 of 72 households in a settlement near a wetland fish there. A student writes, “The people of this settlement are destroying the wetland.” Calculate the share and rewrite the claim fairly.
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18 ÷ 72 × 100 = 25%. Check: 72 ÷ 4 = 18.
Rewrite: “In the survey, 25% of households (18 of 72) fished in the wetland. The survey does not show how much they caught or its effect on the wetland.” The original names a whole group as the cause and uses data that does not measure damage.
Q10 (harder). Place C has 1,800 mm of rain and a mean temperature of 26 °C. Place D has 250 mm of rain and a mean temperature of 6 °C. Compare the likely nutrient stores in the two places, with reasons.
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In C, warmth and rain give fast growth and fast decomposition, so nutrients cycle quickly and are mainly held in the vegetation. The humus layer is thin. In D, cold and dryness give slow growth and slow decomposition, so more of the nutrient store is in slowly rotting litter and soil, and less is held in plants. The comparison uses climate, growth and decomposition in turn.
If you got these wrong
- Q1 to Q3 or Q10 wrong: the climate, vegetation and soil chain needs another look. Revise linking climate, vegetation and soil in a model.
- Q4 to Q6 wrong: the percentage or energy calculation slipped. Revise interpreting a food-web or land-cover dataset, and check percentage change against percentage points.
- Q7 wrong: your explanation listed effects without linking them. Revise explaining a disturbance with a causal chain.
- Q8 wrong: the calculation or the evaluation was too thin. Revise evaluating conservation evidence with limitations.
- Q9 wrong: the claim went beyond the data. Revise avoiding ecological or demographic stereotypes.
When your errors cluster in one place, a Geography tuition lesson can focus on that skill with your own answers in front of you.