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IGCSE Environmental Management Paper 1 — Principles of Environmental Management

Principles of Environmental Management — Mock 1
105 minutes
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6
105:00
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Question 1 — Rocks, ores and mining
Total: 12 marks
(a)[1]
Define the term ore.
Model Answer — 1(a)
rock that contains minerals and metals
the word rock is required. "A metal found in the ground" does not score, because the ore is the rock, not the metal itself
accept "rock containing a metal (compound) in an amount worth extracting"
⚠ If you missed marks here: an ore is not the pure metal. It is the rock you dig up; the metal has still to be taken out of it. A one-mark definition is marked for the exact idea, so write the syllabus wording: rock containing minerals and metals.
(b)[4]
Sandstone is a sedimentary rock. Describe how sandstone is formed from an existing rock such as granite.
Model Answer — 1(b)
any 4 from:
weathering breaks the granite down in place into small particles or grains
erosion loosens and removes those particles from the rock surface
transportation by rivers, wind or ice carries the particles away
deposition / sedimentation: the particles settle out, usually in a sea or a lake, and build up in layers
compaction: the weight of the layers above squeezes the water out and presses the grains together
cementation: dissolved minerals crystallise between the grains and stick them together to form solid rock
the named processes are what earn the marks. A description with no process names is worth at most 2
⚠ If you missed marks here: weathering and erosion are two different words for two different things. Weathering breaks rock down where it is; erosion removes the loosened material. Using one word for both loses a mark. Compaction and cementation are also separate stages — squeezing the grains together is not the same as gluing them.
(c)[1]
Define the term permeability.
Model Answer — 1(c)
the ability of water to pass through the pore spaces of rock and soil
the idea of water passing through is required, and the marker looks for pore spaces
"lets water in" on its own is not enough — a sponge holds water without letting it pass through
⚠ If you missed marks here: permeability is about water going through the rock, not about the rock soaking water up. Sandstone and limestone are permeable; shale, granite and marble are not.
(d)[2]
Some copper is now obtained by phytomining, a method of biological extraction. Describe how phytomining works.
Model Answer — 1(d)
plants are grown on land containing low-grade ore, and they take the metal compounds up through their roots and store them in their tissues
the plants are then harvested and burned, and the metal compound is obtained from the concentrated ash
accept for the first mark: the plants concentrate the metal from ore too poor to be worth mining in the usual way
⚠ If you missed marks here: phytomining is a way of getting metal out, not a way of cleaning land up. Using plants and microorganisms to clean contaminated ground is bioremediation, which is a land restoration strategy. Bioleaching is the other biological method — that one uses bacteria, not plants.
(e)[4]
A company plans to open an opencast mine for copper ore on a hillside directly above a river valley in which crops are grown.
Explain two ways in which the mine could affect the environment of the valley below.
Model Answer — 1(e)
any 2 impacts, each worth 1 mark for the impact and 1 mark for the explanation:
loss of habitat and biodiversity — the vegetation and topsoil are stripped from a large surface area, so the species that lived there lose the conditions they need and their numbers fall
water pollution — rain running off the waste rock carries sediment and dissolved metals downhill into the river, lowering the water quality for the crops and for people downstream
air pollution — blasting and lorry movement raise dust, which settles on the leaves of the crops below and reduces the light reaching them for photosynthesis
noise pollution — blasting and heavy machinery disturb wildlife in the valley, so animals move away from the area
visual pollution — the open pit and the spoil heaps change the appearance of the hillside above the valley
water usage — processing the ore uses large volumes of water, so less is left in the river for irrigating the crops
waste management — overburden and waste rock are stored on the surface above the valley and can be washed down in heavy rain
the second mark in each pair is only for the mechanism: how the mine reaches the valley
⚠ If you missed marks here: "it causes pollution" is one word doing no work. Say which pollution and how it gets there — the mine is above the valley, so run-off, dust and noise all travel downhill. An explain question needs a because.
Question 2 — Soils, crop growth and soil erosion
Total: 12 marks
(a)[2]
Soil contains mineral particles of sand, silt and clay. State two other components of a soil.
Model Answer — 2(a)
any 2 from:
organic content — living organisms (plants, animals, fungi and bacteria)
organic matter from decomposition (dead and decaying material)
gases (air in the pore spaces)
water
accept "living organisms" and "dead organic matter" as two separate answers
⚠ If you missed marks here: "nutrients" is too vague to score on its own — nutrients are not a separate component, they come from the organic content and from inorganic ions. "Pore spaces" is not a component either; it is the space that holds the gases and the water.
(b)[4]
Explain why a loam soil is a good medium for crop growth.
Model Answer — 2(b)
any 4 from:
it has an ideal combination of sand, silt and clay particles, giving plenty of pore spaces
it retains moisture, so the roots have water available between rainfall or irrigation
it lets excess water drain away, so the soil does not become waterlogged and the pore spaces still hold air for the roots
it contains organic content and inorganic ions, supplying nitrate, phosphate and potassium ions for growth
it is easy to cultivate, so a seedbed can be prepared without heavy machinery
⚠ If you missed marks here: "loam is the best soil" is a claim, not an explanation, and scores nothing. Every mark here comes from a property plus what that property does for the plant. Note that two of the marks are opposites that must both be said: loam holds water and also drains excess water — that balance is the whole point of it.
(c)[2]
In a hot, dry region a farmer floods a field with irrigation water every day. After several years the crop yield has fallen and a white crust has appeared on the soil surface.
Explain what has happened to the soil.
Model Answer — 2(c)
this is salinisation, caused by mismanagement of irrigation (the word salinisation, or "a build-up of salt", is required for this mark)
the irrigation water contains dissolved salts; in the heat the water evaporates from the surface and the salts are left behind, so the salt concentration in the topsoil rises
accept for the second mark: the salty soil makes it harder for roots to take up water, which is why the yield falls
⚠ If you missed marks here: this is salinisation, not waterlogging. Waterlogging is water filling the pore spaces so roots cannot get oxygen — the soil would be wet, not crusted. The white crust on the surface is the clue, and it appears because the water leaves and the salt does not.
(d)(i)[2]
Explain how contour ploughing reduces soil erosion.
Model Answer — 2(d)(i)
the furrows are ploughed across the slope, following the contour, instead of up and down it
each furrow acts as a small barrier that holds back and slows the water, so surface run-off is reduced and less soil is carried away
⚠ If you missed marks here: the mark is for the direction plus the effect on run-off. Ploughing up and down a slope makes a set of channels pointing straight downhill, and water runs faster in them and takes more soil with it — saying what contour ploughing avoids is a good way to show you understand it.
(d)(ii)[2]
The same farm also has a steep hillside where the soil is left bare after harvest.
Suggest one further strategy the farmer could use on that hillside, and justify your choice.
Model Answer — 2(d)(ii)
1 mark for a valid strategy: terracing OR maintaining vegetation cover (a cover crop) OR bunds OR wind breaks OR adding organic matter
1 mark for a justification that refers to the slope being steep or the soil being bare, for example:
terracing — cuts the steep slope into a series of near-flat steps, so water no longer runs the full length of the slope and soil movement downhill is reduced
maintaining vegetation cover — roots bind the bare soil and the leaves take the force of the raindrops; it also costs far less than terracing, which matters for a small farm
bunds — low banks built along the slope hold back run-off so the water soaks in instead of running off
organic matter — improves soil structure so the soil holds together and absorbs more water
no justification mark for "because it stops erosion", which only repeats the question
⚠ If you missed marks here: a suggest-and-justify question gives half its marks for the reason, so a named strategy on its own is capped at 1. Tie the reason to the situation you were given — here that means the slope is steep and the soil is bare, and terracing and vegetation cover each answer one of those directly.
Question 3 — Water supply, treatment and pollution
Total: 14 marks
(a)[1]
Define the term potable water.
Model Answer — 3(a)
water that is safe to drink
the words safe to drink are required
"clean water" or "pure water" on their own do not score
⚠ If you missed marks here: potable does not mean chemically pure. Potable water still contains dissolved substances — the test is only whether drinking it is safe. Distilled water is pure but is not what the definition asks for.
(b)[4]
Water taken from a river is treated at a water treatment works before it is supplied to homes.
Describe the four stages of this treatment, in order, and state what each stage does.
Model Answer — 3(b)
screening — the water passes through a mesh or screen that holds back large floating objects such as leaves, sticks and rubbish
sedimentation — the water is held still in a tank so the heavier suspended particles sink to the bottom
filtration — the water passes through beds of sand and gravel, which trap the smaller suspended particles still left
chlorination — chlorine is added, which kills bacteria and other microorganisms in the water
1 mark per stage. Both the name and what it does are needed for each mark
⚠ If you missed marks here: naming the four stages without saying what each one does is worth 0, because the question asked for both. Also keep the order: sedimentation before filtration. Sending untreated river water straight onto a sand filter would clog it, which is exactly why the big particles are settled out first.
(c)[3]
A coastal town has no river and takes its water from the sea. Describe how distillation produces potable water from sea water.
Model Answer — 3(c)
any 3 from:
the sea water is heated until it boils
the salt remains behind in the liquid, because the salt does not evaporate
the steam given off is pure water
the steam is cooled and condensed to form liquid potable water
⚠ If you missed marks here: the commonest error is writing that the salt evaporates and the water is left. It is the other way round: the water leaves as steam and the salt stays. The second common loss is stopping at "the steam is collected" — you have to cool and condense it, or you have not made any liquid water.
(d)[2]
The town builds a desalination plant that produces 6000 m³ of potable water each day. The town has 48 000 people, who each use an average of 180 litres of water per day.
Calculate the percentage of the town’s daily water demand that the plant supplies. (1 m³ = 1000 litres.)
Model Answer — 3(d)
M1 daily demand 48 000 × 180 = 8 640 000 litres = 8640 m³
A1 6000 ÷ 8640 × 100 = 69.4% (accept 69.4, 69.44, or 69%)
M1 is available for the correct demand in either unit, as long as both quantities are then compared in the same unit
⚠ If you missed marks here: the whole question is the unit conversion. Dividing 6000 m³ by 8 640 000 litres gives 0.0694%, which should look wrong immediately — a plant that size does not supply a fourteen-hundredth of a town. Convert one quantity so the two match before you divide, and write the unit next to every number as you go.
(e)[4]
A river flows past fields on which inorganic NPK fertiliser has been spread. After heavy rain the river water turns green, and two weeks later large numbers of dead fish are found.
Explain how the use of the fertiliser led to the death of the fish.
Model Answer — 3(e)
any 4 from, and the steps must lead on from one another:
rain leaches the fertiliser (nitrate and phosphate ions) out of the soil and into the river — nutrient enrichment
the extra nutrients cause rapid growth of algae at the surface, an algal bloom — this is why the water turns green
the layer of algae blocks the light, so the plants below it cannot photosynthesise and they die
bacteria and other decomposers break down the dead algae and dead plants, and their numbers increase
the decomposers use oxygen in aerobic respiration, so the concentration of dissolved oxygen in the water falls
the fish cannot get enough oxygen to respire and so they die
the whole process is called eutrophication; naming it does not by itself earn a mark
⚠ If you missed marks here: the algae do not poison the fish, and the fertiliser does not poison them either. The link is oxygen, and it runs through the decomposers — the fish died because the bacteria breaking down the dead algae used up the dissolved oxygen. If your answer jumps from "algae grow" straight to "fish die", you have skipped the two steps that carry most of the marks.
Question 4 — The atmosphere, climate change and acid rain
Total: 14 marks
(a)[1]
Define the term greenhouse gas.
Model Answer — 4(a)
a gas that absorbs radiation and emits the energy as thermal (heat) energy
both halves are required: it must say the gas absorbs radiation and that it gives the energy out again as heat
"a gas that traps heat" is not precise enough for the mark
⚠ If you missed marks here: a definition that only says "causes global warming" describes an effect, not what the gas does. Learn the two-step wording — absorbs radiation, emits the energy as thermal energy — and remember the three named examples: carbon dioxide (CO₂), water vapour (H₂O) and methane (CH₄).
(b)[4]
Describe the natural greenhouse effect.
Model Answer — 4(b)
any 4 from:
solar radiation passes through the Earth’s atmosphere
some of the solar radiation is absorbed by the land and the oceans, which heats the Earth
some of the solar radiation is reflected back into space
some is absorbed by greenhouse gases and clouds and re-emitted back towards the Earth’s surface
this natural process keeps the Earth warm enough to support life
⚠ If you missed marks here: the natural greenhouse effect is not a problem — without it the Earth would be too cold for life, and the last mark point is there to make you say so. The enhanced greenhouse effect is the one caused by higher concentrations of greenhouse gases. If the question says natural, describing pollution and fossil fuels earns nothing.
(c)[3]
A power station burns coal that contains sulfur compounds. A lake 200 km downwind of the power station has become more acidic and its fish population has fallen.
Explain how burning the coal has led to the fall in the fish population.
Model Answer — 4(c)
burning the coal releases sulfur dioxide (SO₂) into the atmosphere (the gas must be named)
the sulfur dioxide reacts with oxygen and water vapour in the atmosphere to form acid rain, which is carried by the wind before it falls — which is how a lake 200 km away is affected
the acid rain falls into the lake and acidifies the water, lowering its pH, and the fish cannot survive the lower pH, so the population falls
⚠ If you missed marks here: "acid rain killed the fish" is the conclusion, not the explanation, and it scores one mark at most. The chain has three links and the middle one is the one people drop: the sulfur dioxide has to react with oxygen and water vapour to become acid rain, and the wind carries it, which is why the damage happens 200 km away. Note the gas is sulfur dioxide, not carbon dioxide — carbon dioxide is the greenhouse gas, and it is oxides of nitrogen from vehicle engines that make up the other cause of acid rain.
(d)[6]
Two strategies used to manage the impacts of acid rain are flue-gas desulfurisation at power stations and catalytic converters on vehicles.
Discuss the benefits and limitations of these two strategies.
Model Answer — 4(d) — extended response, marked by level
LevelWhat the answer does
Level 3
5–6 marks		Benefits and limitations of both strategies, each developed with a reason rather than listed. Ends with a judgement that follows from the points actually made.
Level 2
3–4 marks		Both sides are present, but mostly about one strategy, or points are stated without development. A judgement may be given but is not supported by the points above it.
Level 1
1–2 marks		Simple statements, or one side only. An answer that gives only benefits, or only limitations, cannot go above 2 marks however long it is.
Level 0
0 marks		Nothing creditable.
Benefits — flue-gas desulfurisation: removes sulfur dioxide from the waste gases by reacting it with calcium carbonate or calcium oxide, so far less sulfur dioxide reaches the atmosphere; it treats one large source at a single point, so one installation cuts a large share of a country’s sulfur dioxide; the power station can keep running on the fuel it has.
Limitations — flue-gas desulfurisation: expensive to fit and to run, and the cost is usually passed on to electricity users; it uses energy, so more fuel is burned for the same electricity; it produces a solid waste that has to be handled; it does nothing about oxides of nitrogen, which are the other cause of acid rain.
Benefits — catalytic converters: remove oxides of nitrogen from vehicle exhausts, so they deal with the cause that flue-gas desulfurisation cannot; they reach a source spread across millions of vehicles that could never be treated at one point; once fitted they work without the driver doing anything.
Limitations — catalytic converters: they add to the cost of every vehicle; they only work on vehicles that have them, so legislation and enforcement are needed and older vehicles are not covered; they do not reduce sulfur dioxide; they do not reduce the number of vehicles, so a growing vehicle fleet can cancel out the gain.
Judgements that would earn the final mark: the two are complements rather than alternatives, because one deals with sulfur dioxide and the other with oxides of nitrogen, so using only one leaves half the cause untouched. OR where most sulfur dioxide comes from a few power stations, flue-gas desulfurisation gives the larger reduction per unit of money spent; where road transport dominates, catalytic converters matter more. OR neither removes acid already in soils and lakes, so both limit further damage rather than reversing it, which is why transport policies that reduce vehicle numbers are also on the syllabus.
a judgement with no reason attached earns nothing
⚠ If you missed marks here: discuss means both sides, and the cap on a one-sided answer is real — three excellent paragraphs of benefits still score 2. Check your answer has the word however or but in it somewhere. The second thing markers look for is whether you noticed that these two strategies remove different gases; treating them as two ways of doing the same job misses the strongest judgement available.
Question 5 — Marabo: tectonic setting and a tropical cyclone
Total: 14 marks
Source A — read this before answering Question 5
Marabo is an island of 90 000 people in a tropical ocean, 12° south of the Equator. The island stands on the edge of an ocean trench, at a place where one oceanic plate is moving beneath another. Marabo has one active volcano, and small earthquakes are felt several times a year.

Almost everyone lives on the flat coastal strip. Until about 1995 a belt of mangrove forest roughly 300 m wide ran along most of that coast. Much of the forest has since been cleared for shrimp ponds and for building land.

In February 2024 a tropical cyclone crossed Marabo. A storm surge pushed sea water up to 1.5 km inland across the cleared coastal strip. Wells used for drinking water were flooded, and the island’s only sewage treatment works was out of action for eleven days. In the four weeks that followed, the island clinic recorded 480 cases of diarrhoeal illness, compared with about 35 cases in a normal month.
(Marabo is not a real place. Use only the information given here and your own knowledge of the syllabus.)
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Mean sea-surface temperature / °C28.428.929.128.627.826.926.125.826.327.227.928.2
Table 5.1 — mean monthly sea-surface temperature in the ocean around Marabo.
(a)[3]
Source A describes one oceanic plate moving beneath another.
Name this type of plate boundary and explain why an active volcano has formed on Marabo.
Model Answer — 5(a)
convergent OR destructive plate boundary (either word scores; "subduction zone" alone is not the name of the boundary, so allow it only if the word convergent or destructive also appears)
one plate is subducted, moving down beneath the other into the mantle, where it melts and forms magma
the magma is less dense than the rock around it, so it rises through the crust and reaches the surface, building a volcano (a line of volcanoes forms along such a boundary)
convection currents in the mantle are what drive the plates together in the first place — credit this in place of the second point
⚠ If you missed marks here: "moving beneath" in the source is the whole clue — that is subduction, which happens at a convergent (destructive) boundary. At a divergent (constructive) boundary the plates move apart, and at a conservative boundary they slide past each other and you get earthquakes with no volcano. Naming the boundary alone is 1 of 3 marks; the other two are for what happens to the subducted plate and what the magma then does.
(b)(i)[1]
Using Table 5.1, calculate the range of the mean sea-surface temperature around Marabo over the year.
Model Answer — 5(b)(i)
3.3 °C
from 29.1 °C in March, the highest value in the table, minus 25.8 °C in August, the lowest: 29.1 − 25.8 = 3.3
the unit is needed for the mark; a bare 3.3 with no unit does not score
⚠ If you missed marks here: a range is one number, not two — "25.8 °C to 29.1 °C" describes the spread but does not answer the question asked. And you have to scan every one of the twelve values: the lowest is August, two months after the middle of the year, not December.
(b)(ii)[2]
Farmers on the coastal strip of Marabo grow vegetables and graze a small number of cattle.
Explain why the crop yields on this land may stay low for several years after the storm surge described in Source A.
Model Answer — 5(b)(ii)
any 2 from, 1 mark each — each mark needs the effect and the reason:
sea water soaked into the soil and left salt behind when it drained or evaporated, so the soil is now salty (salinisation) and crops grow poorly in it
the salt has to be washed out of the soil by rainfall or irrigation, which takes more than one season, so the land does not recover in the first year
the surge washed away or buried the topsoil, which holds the nutrients and the humus, and topsoil is replaced only slowly
the crops standing in the fields at the time were lost, so seed and money are needed before the land can be planted again
cattle that drowned or that had no fresh water or grazing left less manure, so less organic matter is returned to the soil
do not credit "the plants were flooded" on its own — that explains the first harvest, not several years
⚠ If you missed marks here: the question says for several years, so an answer about the crops that were standing at the time only reaches the first mark. What lasts is what the sea water left in the ground: salt, and the loss of topsoil. This is the same salinisation that the syllabus attaches to irrigation, arriving here by a different route.
(c)[4]
Explain two ways in which the events described in Source A could have affected human health on Marabo.
Model Answer — 5(c)
any 2, each worth 1 mark for the effect and 1 mark for the explanation:
contamination of drinking-water supplies — the storm surge flooded the wells with sea water, so the water is salty and no longer potable and people have to drink from other, less safe sources
water-related disease — with the sewage works out of action for eleven days, untreated sewage reached the water people were using, and bacterial diseases such as cholera spread; Source A shows this happening, with 480 cases against about 35 in a normal month
injury and loss of life — buildings on the coastal strip are damaged and debris is carried inland by the surge
loss of crops and livestock — the surge covered the flat coastal strip with salt water, so food supply on a small island falls and malnutrition becomes more likely
standing flood water left behind gives mosquitoes places to breed, raising the risk of malaria
answers that use the numbers in Source A are credited, but the numbers are not required
⚠ If you missed marks here: a source is put in front of you so that you use it. The eleven days without sewage treatment and the jump from 35 cases to 480 are the evidence for the disease answer, and quoting them turns a general point into an explained one. Do not write two versions of the same point — "people got ill" and "people caught diseases" is one mark, not two.
(d)[2]
Explain how the clearance of the mangrove forest since 1995 increased the damage done by the storm surge.
Model Answer — 5(d)
any 2 from:
the belt of forest slowed the water and took some of its energy, so with 300 m of it removed the surge travelled further inland — Source A gives 1.5 km
the roots of the trees bound the soil together; without them the coastal soil is eroded more easily and the coast is less stable
vegetation intercepts water and increases infiltration, reducing surface run-off, so its removal leaves more water flowing across the surface
the ponds and cleared ground that replaced the forest are flat and open, so there is nothing to slow the water at all
⚠ If you missed marks here: "the trees stopped the water" states the outcome without the mechanism, and that is 1 mark at most. Say how: the trees slow the water and take energy out of it, and their roots hold the soil. This is one of the impacts of deforestation on the syllabus — silting and flooding — so it is examinable as forest management as well as as a hazard.
(e)[2]
Describe two strategies that the government of Marabo could use before the next tropical cyclone to reduce its impacts.
Model Answer — 5(e)
any 2 from, 1 mark each:
monitoring and warning — track storms by satellite and issue warnings in time for people to act
disaster preparation — written plans, practice drills, stores of emergency supplies, and trained emergency rescue teams
structure of buildings — build or strengthen buildings so they withstand high winds and flood water
shelters — build shelters on higher ground, above the reach of a storm surge
evacuation — plan routes and transport in advance so the coastal strip can be cleared when a warning is given
a bare list of two words is enough here, since the question says describe — but a short phrase of detail protects the mark
⚠ If you missed marks here: read the word before. Rebuilding damaged areas and international aid are real strategies but they belong after the event, so they score nothing on this question. Watch this on flooding and tectonic questions too, where the syllabus splits the same list into before, during and after.
Question 6 — The Tanoa forest: energy, carbon and conservation
Total: 14 marks
Source B — read this before answering Question 6
The Tanoa forest covers about 3 000 km² of tropical hills. In 2016 a road was cut through it to reach a new copper mine. Since then about 12% of the forest has gone: some cleared for the mine and the ground where its waste rock is tipped, some for cattle pasture along the road, and some by families who clear a small plot, grow crops on it for a few years and then clear another. Timber that cannot be sold is burned where it falls.

Several of the forest’s tree species grow nowhere else. Government scientists estimate that the number of forest cats has fallen from about 400 in 2016 to about 240 today. The government has to decide how the remaining forest will be managed.
(Tanoa is not a real place. Use only the information given here and your own knowledge of the syllabus.)
Forest catTree snakeTree frogFruit batForest ratLeaf beetleTanoa treeGround shrubeach arrow points from the organism that is eaten to the organism that eats it
Fig. 6.1 — part of the food web of the Tanoa forest. The tanoa tree and the ground shrub are green plants.
(a)(i)[1]
Using Fig. 6.1, name the apex predator of this food web.
Model Answer — 6(a)(i)
the forest cat
it is the one predator in Fig. 6.1 with no arrow leaving it, so nothing in this web feeds on it
⚠ If you missed marks here: an apex predator is the one at the top of the chain, so look for the organism that no arrow leaves. The tree snake is a predator too, but an arrow runs from it to the forest cat, so something eats it. Reading the arrows the wrong way round is the usual cause of picking a plant.
(a)(ii)[2]
Using Fig. 6.1, name one secondary consumer and explain how the food web shows that it is a secondary consumer.
Model Answer — 6(a)(ii)
the tree snake OR the tree frog — either scores the first mark
the second mark is for reading the chain back to a plant: the tree snake feeds on the fruit bat, and the fruit bat feeds on the tanoa tree, which is a producer — so the snake is the second consumer along the chain
for the tree frog: it feeds on the leaf beetle, and the leaf beetle feeds on the ground shrub, which is a producer
allow the wording "it eats a primary consumer" for the second mark, provided the primary consumer is named from Fig. 6.1
the forest rat is a primary consumer, not a secondary one, even though it feeds on two different plants
⚠ If you missed marks here: count steps from the plant, not arrows into the organism. The forest rat has two arrows arriving at it, but both come from green plants, so it is still only one step away and is a primary consumer. And the explanation mark needs the chain written out — naming the animal and stopping there is 1 mark of 2.
(b)(i)[2]
The producers in one square metre of the Tanoa forest transfer 24 000 kJ of energy each year.
Calculate the energy per year that is available to the apex predator in that square metre. Show your working.
Model Answer — 6(b)(i)
M1 uses 10% of the energy passing to the next trophic level, applied over the three transfers between the producer and the forest cat: 24 000 × 0.1 × 0.1 × 0.1, or 24 000 ÷ 1 000
A1 24 kJ per year (accept 24 kJ per m² per year)
the chain is producer → primary consumer → secondary consumer → tertiary consumer: tanoa tree → fruit bat → tree snake → forest cat, so 24 000 → 2 400 → 240 → 24
M1 is available even if the arithmetic goes wrong, provided three transfers of 10% are clearly shown
if you named a different animal in (a)(i), mark this part on the number of transfers your animal actually needs — the error is not penalised twice
⚠ If you missed marks here: the answer people write is 240 kJ, because they count the boxes instead of the arrows. There are four trophic levels but only three transfers between them, so the energy is divided by ten three times, not twice. Write the chain out before you start dividing.
(b)(ii)[2]
Explain why so little of the energy captured by the tanoa trees reaches the apex predator.
Model Answer — 6(b)(ii)
only about 10% of the energy at one trophic level is passed on to the next, and there are three of these steps between the tanoa tree and the forest cat, so the energy falls to a thousandth
the other 90% is used or lost in life processes — any 2 named from: movement, respiration, digestion and excretion (two must be named for this mark)
allow, in place of one of the named processes, that energy released by respiration is lost to the surroundings as heat
allow that not all of an organism is eaten, or not all of what is eaten is digested, so the energy in it is not passed on
⚠ If you missed marks here: "the cat is at the top so there is less left" just restates the question. The two marks are for the 10% rule applied over the right number of steps, and for saying where the missing energy actually goes: into movement, respiration, digestion and excretion. Name two of those processes — one is not enough.
(c)[2]
Timber that cannot be sold is burned where it falls.
Using the carbon cycle, explain how clearing and burning part of the Tanoa forest changes the amount of carbon dioxide in the atmosphere.
Model Answer — 6(c)
the amount of carbon dioxide rises. 1 mark for each of two different routes, from:
combustion — burning the timber releases the carbon that was stored in the wood back to the atmosphere as carbon dioxide
less photosynthesis — the trees that would have taken carbon dioxide out of the air have gone, so less is removed; the forest was a carbon sink and store, and the store is now smaller
decomposition — decomposers break down the dead roots and leaf litter left behind and release carbon dioxide by respiration
a mark needs the direction of the carbon stated. Naming a process on its own, with nothing about carbon entering or leaving the air, does not score
both marks may not be taken from the same route, so "burning releases carbon dioxide" twice in different words is 1 mark
⚠ If you missed marks here: this needs two routes, not one, and they pull in opposite directions in the cycle: carbon is added by combustion and is no longer removed because the trees are gone. The second one is the one that gets left out. Note also that the trees do not have to be burned for the carbon to return — decomposers respire it back just as surely, only more slowly.
(d)[5]
The government must choose one of two ways of managing the forest that is left.

Option 1 — make the whole of the remaining forest a national park, in which logging, mining and farming are not allowed.
Option 2 — license sustainable forestry, in which a set number of trees may be cut each year and replacement trees must be planted.

Discuss the benefits and limitations of each option, and recommend which option the government should choose.
Model Answer — 6(d)
How the 5 marks are awarded: 1 mark for a developed benefit of one option, 1 for a developed limitation of that same option, 1 for a developed benefit of the other option, 1 for a developed limitation of that option, and 1 for a recommendation that follows from the points made. A point is developed when it says what follows for the forest, its wildlife or the people, not only what the option is.
Maximum 2 marks if only one option is discussed, however well — the question names both.
Option 1, national park — benefits, any from: it protects the whole habitat at once, so every species in it is conserved together, including the tree species that grow nowhere else; it protects the forest cat, whose numbers have already fallen from about 400 to about 240; it keeps the forest as a carbon sink and store and keeps its part in the water cycle, so flooding and soil erosion downstream are reduced; it can earn money from ecotourism and education, and can be used for research.
Option 1 — limitations, any from: it earns nothing from timber, so the boundary, the staff and the patrols all have to be paid for from elsewhere; a park boundary is hard to enforce when a mine road already runs through the forest; it takes away land and timber that families and the mining company are using now, so it may be resisted or simply ignored; the clearing along the road has already fragmented the forest, and a line on a map does not put that back.
Option 2, sustainable forestry — benefits, any from: timber income continues, so the strategy pays for its own monitoring and is more likely to be accepted and kept to; replanting keeps tree cover, so soil erosion, silting and carbon release are limited; local people keep their work, which reduces the reason to clear new plots; it is what sustainable management of forests means — balancing the needs of the environment, wildlife and people while conserving the forest for future generations.
Option 2 — limitations, any from: someone has to check that the agreed number of trees is not exceeded, and monitoring costs money and can be evaded; even selective logging needs tracks, which fragment the habitat and open the forest to others; replanted forest usually holds fewer species than the forest it replaces, so biodiversity and genetic diversity still fall; the rare tree species may be exactly the ones worth cutting; the yield is lower than clearing the land outright, so the pressure to break the licence remains.
Recommendation: either option can earn the fifth mark. For example: sustainable forestry, because it pays for itself and a poor government cannot fund patrols indefinitely; or the national park, because the tree species found nowhere else cannot be replanted once they are gone, so the risk of getting the logging quota wrong is not worth taking. A third answer — park the areas holding the unique species and license forestry in the rest — is creditworthy if it is argued from the points made. The mark is for a conclusion that follows from the answer, not for choosing correctly; there is no correct choice here.
⚠ If you missed marks here: the word discuss is what caps most answers. Four of the five marks require you to write against your own preference: a benefit and a limitation for each option, so a strong one-sided case is worth 2. Plan four boxes before you write. The fifth mark is not for picking the right side — it is for a recommendation that uses the points you actually made, so refer back to one of them by name.

Self-Assessment

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IGCSE Environmental Management 0680 — Paper 1 — Principles of Environmental Management — Principles of Environmental Management — Mock 1
For examination preparation only. Not an official Cambridge Assessment paper.