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IGCSE Environmental Management Paper 1 — Topic 2 Land — Challenge

Principles of Environmental Management — Topic 2 Challenge
45 minutes
40
7
45:00
0680
This paper covers the whole of Topic 2. The questions are not in syllabus order and they are not one question per sub-topic. Material from 2.1 to 2.3 is mixed across every question, exactly as Cambridge mixes it, so do not expect Question 1 to be about 2.1.

Instructions

Question Navigation

Question 1 — What soil is made of, and why it matters
Total: 6 marks
(a)[2]
A soil contains mineral particles, organic content, gases and water. State the two things that the organic content of a soil consists of.
Model Answer — (a)
living organisms in the soil: plants, animals, fungi and bacteria
organic matter from decomposition, that is the partly broken down remains of dead plants and animals (humus)
one mark for each of the two; naming only earthworms, or only humus, gives one mark, not two
⚠ If you missed marks here: the organic content is a pair, not a single idea. Living organisms are the first half and dead, decomposing material is the second, and the syllabus lists both. Candidates who write "dead plants and animals" alone have written half the answer and score one. Note also that "organic content" is not the same as "organic matter": the content includes the living organisms as well.
(b)[2]
Explain why a sandy soil dries out quickly and loses nutrients.
Model Answer — (b)
sand particles are large, so the pore spaces between them are large
water drains through the large pores quickly and dissolved mineral ions are carried away with it, so both water and nutrients are lost
the mark is for the link from particle size to pore size to drainage, not for the word "sandy" on its own
⚠ If you missed marks here: this is a mechanism question and the mechanism is always the same: particle size controls pore size, and pore size controls everything else. An answer that says "sand does not hold water" restates the question rather than explaining it. Say large particles, large pores, fast drainage, nutrients washed out in the draining water and all of it is credited.
(c)[2]
A field floods and the soil stays waterlogged for two weeks. The crop dies even though there is plenty of water. Explain why.
Model Answer — (c)
the pore spaces fill with water, so air (oxygen) is excluded from the soil
the roots cannot respire, so root cells die and the plant can no longer take up water or ions
accept the same idea expressed as "no oxygen for aerobic respiration in the root"
⚠ If you missed marks here: this is the classic "but there is water everywhere" trap and the answer is about air, not water. Roots are living tissue and respire, and respiration needs oxygen. Answers that say the roots "drown" or "rot" describe what is seen rather than why it happens, so they do not score the second mark. The two marks are (1) water fills the pores so oxygen is excluded and (2) roots cannot respire.
Question 2 — Loam, plant nutrients and soil pH
Total: 6 marks
(a)[3]
Loam is described as a good medium for crop growth. Explain three reasons why, giving the mechanism in each case.
Model Answer — (a)
ideal combination of mineral particles and pore spaces: a mixture of large sand grains and small clay particles gives both large pores (air in, excess water out) and small pores (water held against gravity)
retains moisture: the clay and the organic matter hold water in the small pores, so the crop has a supply through a dry spell
contains organic content and inorganic ions: decomposing organic matter releases nitrate, phosphate and potassium ions steadily into the soil water
allows excess water to drain: the large pores let surplus water pass, so the soil does not waterlog and roots can still respire
easy to cultivate: neither as heavy and sticky as clay nor as loose as sand, so it can be ploughed over a wider range of weather
any three of the five, each with its mechanism, one mark each
⚠ If you missed marks here: a named reason on its own scores nothing here because the command word is explain. "Loam retains moisture" is the claim; "because the clay and organic matter hold water in the small pores" is the mark. The five syllabus reasons are worth learning as five, because a five-mark version of this question is a real possibility. The syllabus states plainly that you do not need to know what proportion of a soil is mineral, organic, air or water, so do not quote such figures: they cannot be asked for and they earn nothing.
(b)[2]
A crop is short of nitrogen. State the ion in which a plant takes up nitrogen from the soil, and state what the plant needs nitrogen for.
Model Answer — (b)
nitrate ions, NO₃⁻
needed to make amino acids and so proteins, and therefore for leaf and stem growth
accept "for growth of leaves" for the second mark; do not accept "for photosynthesis" alone
⚠ If you missed marks here: the syllabus names the exact ion for each of the three nutrients and expects it: nitrogen as nitrate, phosphorus as phosphate, potassium as potassium ions. Writing "nitrogen" when the question asks for the ion does not score, and neither does "nitrite". Remember that ions can only enter a root in solution, which is why the water content of a soil and its nutrient content are the same story told twice.
(c)[1]
Explain why a soil can be well supplied with mineral ions and still leave a crop short of nutrients.
Model Answer — (c)
if the pH is too acidic or too alkaline the ions become locked into forms that the roots cannot absorb, so the nutrients are present but not available
⚠ If you missed marks here: the word to reach for is available. Present and available are not the same thing, and that distinction is the whole mark. This is also why farmers add lime: not to add nutrients but to raise the pH of an acidic soil so the nutrients already there can be taken up.
Question 3 — Weather, the growing season and photosynthesis
Total: 6 marks
(a)[1]
Define the term weather.
Model Answer — (a)
the day-to-day conditions of the atmosphere in a location
all three elements are needed: day-to-day, conditions of the atmosphere, in a location
⚠ If you missed marks here: this is a definition mark, marked against one exact form of words, and its partner definition is climate from Topic 4. Weather is what it is doing today; climate is the pattern over many years. Candidates lose this mark by writing the wrong one of the pair, or by writing "the rain and temperature outside", which leaves out the timescale.
(b)[2]
Explain why a long growing season increases the mass of crop obtained from one hectare of land in a year.
Model Answer — (b)
a longer period when temperature, water and light are all sufficient means more total photosynthesis, so more glucose is made and more plant material is built
a long season may also allow more than one harvest from the same land in a year
accept "more days of growth so a larger plant at harvest" for the first mark
⚠ If you missed marks here: the mark is not for saying "the crop has longer to grow", which is the question in different words. Name photosynthesis as the process whose total over the season sets the yield, and add the second harvest as the separate second mark. Note the growing season is limited by whichever factor runs out first, which may be cold in one place and the end of the wet season in another.
(c)[2]
A greenhouse grower raises the temperature well above the optimum for the crop. Explain why the rate of photosynthesis falls.
Model Answer — (c)
the enzymes that control photosynthesis are denatured, that is damaged so that they no longer work
so the reactions they control slow down and the rate falls; very high temperatures also cause water loss and wilting, which closes stomata and reduces carbon dioxide uptake
accept either the enzyme route or the water-loss route for the second mark, provided the first is the enzymes
⚠ If you missed marks here: the shape of the curve is what 0680 wants: the rate rises to an optimum and then falls. Answers that say "it is too hot so the plant dies" describe the outcome without the cause. The word the mark scheme looks for is denatured. The biochemistry beyond that belongs to Biology, so do not spend time on it here.
(d)[1]
Some areas of the world have a marked dry season. State one way in which a dry season limits crop growth.
Model Answer — (d)
there is too little water for photosynthesis and to keep cells turgid, so the crop wilts or fails
or: the growing season is limited to part of the year, so only one harvest is possible
or: the soil dries, cracks and is left bare, so it is blown away by the wind
⚠ If you missed marks here: this is a one-mark stated objective, so one clear consequence is enough, but it must be a consequence for crop growth. "It does not rain" is the definition of a dry season, not an effect of one. It is worth remembering that this objective is the reason irrigation, rainwater harvesting and mulching matter so much in 2.2.3.
Question 4 — Types of agriculture and sustainable food production
Total: 5 marks
(a)[2]
Define sustainable food production.
Model Answer — (a)
the production of sufficient food for the present generation
using methods that ensure future generations can grow food from the same land
one mark for each half of the definition
⚠ If you missed marks here: this definition has two halves and most candidates write only the second. Sustainability in this syllabus never means growing less food; it means growing enough, by methods that leave the land able to do it again. An answer that says "farm less intensively" without saying how the food is still produced has answered half the question and scores one.
(b)[3]
A farm grows a single crop of wheat across 400 hectares, using tractors and combine harvesters, and sells the whole harvest. Give three terms from the syllabus that describe this farm, and justify each one in a few words.
Model Answer — (b)
arable: it grows crops rather than raising livestock
commercial: the harvest is sold for profit rather than eaten by the farmer and the family
monoculture: a single crop species is grown over a large area
accept intensive in place of one of these only if it is justified by high inputs of machinery, fertiliser or pesticide per hectare
one mark for each correct term with a justification that fits
⚠ If you missed marks here: the point of this question is that the classifications sit on different axes, so one farm can be several of them at once, and saying so is the sign that you understand the classification rather than having memorised it. The term alone is not enough, because the command asks you to justify. Also note that "intensive" and "monoculture" are descriptions of how a farm operates, not verdicts on it, so do not turn this into a criticism of the farm.
Question 5 — Strategies to increase food production and crop yield
Total: 5 marks
(a)[2]
Explain two ways in which crop rotation raises the yield obtained from a field.
Model Answer — (a)
different crops take up different ions in different proportions, so no single nutrient is stripped out of the soil; including a legume restores nitrogen naturally
pests and diseases specific to one crop cannot build up in the soil from year to year, so losses to them are smaller
one mark each, and each needs its mechanism, not just the words "it is better for the soil"
⚠ If you missed marks here: rotation is a describe and explain objective, so a named strategy alone scores one mark at most and usually none. There are two separate mechanisms here, one about nutrients and one about pests, and a good answer gives both rather than two versions of the same one. The legume detail is worth adding because it turns a vague "the soil recovers" into a stated mechanism.
(b)[2]
A farmer replaces flood irrigation with trickle (drip) irrigation. Explain two advantages of this change.
Model Answer — (b)
water is delivered through pipes directly to the base of each plant, so almost none is lost to evaporation or to the bare ground between plants: more of the water applied reaches the crop
the soil is not saturated, so waterlogging and salinisation are reduced and the roots can still respire
accept "the amount can be matched to what the crop needs" as an alternative second mark
⚠ If you missed marks here: the common answer here is "it saves water", which is the claim rather than the explanation. Say where the water goes and why less is lost. The second mark is the one most often missed: drip irrigation is not just efficient, it also avoids the salinisation and waterlogging that mismanaged flood irrigation causes, and that link back to 2.2.4 is worth making.
(c)[1]
State what is meant by a genetically modified organism.
Model Answer — (c)
an organism whose genetic material has been changed by removing, changing or inserting individual genes to give favourable characteristics
⚠ If you missed marks here: this is a definition taken word for word from the syllabus, so learn it word for word. "An organism that has been changed in a laboratory" is too vague to score. The three verbs matter (removing, changing, inserting) and so does the purpose (to give favourable characteristics).
Question 6 — What happens when a strategy is pushed too far
Total: 4 marks
(a)[3]
A farmer applies far more inorganic NPK fertiliser than the crop can absorb. Six months later the fish in a lake beside the farm are dead. Describe the chain of events that links the two.
Model Answer — (a)
leaching: the excess fertiliser dissolves in rainwater and drains out of the soil into the lake
nutrient enrichment and algal bloom: the added nitrate and phosphate feed the algae, which multiply into a bloom covering the surface and blocking the light, so the plants beneath die
decomposers and oxygen: when the algae and plants die the decomposers multiply and use up the dissolved oxygen in the water, so the fish suffocate
this is marked as an ordered chain: the three marks are for the three linked stages, in order
⚠ If you missed marks here: the final mark is nearly always the dissolved oxygen, and it is the one most often missing. The fish do not die because the algae poison them and they do not die because the water is green. They die because decomposers respiring aerobically have removed the oxygen dissolved in the water. Write "dissolved oxygen" and you have it. Naming the word "eutrophication" without the chain scores one mark at most, because the command word is describe.
(b)[1]
Explain why pest resurgence happens after a broad-acting insecticide has been used.
Model Answer — (b)
the insecticide also kills the natural predators of the pest, so when the pest population recovers there is nothing left to hold it back and its numbers rebound higher than before
⚠ If you missed marks here: resurgence and resistance are two different things and they are constantly swapped. Resistance is about the pests themselves: a few survive, breed, and the resistant form spreads. Resurgence is about the predators: they are killed too, so the pest comes back unchecked. If your answer mentions surviving pests breeding, you have described resistance and this mark is lost.
Question 7 — Soil erosion on a hillside farm
Total: 8 marks
(a)[2]
Deforestation of a hillside is listed as a cause of soil erosion. Explain why clearing the trees increases the rate at which soil is eroded from the slope.
Model Answer — (a)
the tree roots bound the soil particles together; once the trees are gone there is nothing holding the soil
the canopy intercepted the rain, so drops reached the ground gently; on bare ground rain strikes the soil at full force, dislodging particles, and surface run-off increases because less water soaks in
one mark for roots, one mark for interception and run-off
⚠ If you missed marks here: there are two separate mechanisms here and most answers give only the roots. Interception is the second one and it is worth a mark on its own: a canopy takes the energy out of the falling rain before it reaches the soil. "Trees stop erosion" is the claim, not the explanation. Remember also that topsoil forms at a rate of millimetres per century, so this loss is permanent on any human timescale.
(b)[6]
A farmer works a steep hillside in a region with a heavy wet season and a long dry season. She is losing topsoil in both seasons and her yields are falling.

Discuss the strategies she could use to reduce soil erosion on her land, and come to a judgement about which she should do first.
Model Answer — (b)
Wet season, water on a slope. Terracing cuts the long slope into level steps, so water reaching a step stops and soaks in rather than running on, never builds up the speed needed to carry soil, and any soil that does move is caught on the step below. Contour ploughing runs each furrow across the slope so it acts as a small barrier holding water back and letting it infiltrate; ploughing up and down does the opposite and turns every furrow into a channel. Bunds are low banks of earth or stone built across the slope that trap water behind them and catch soil already moving.
Dry season, wind on bare ground. Wind breaks are rows of trees or hedges planted across the prevailing wind; they slow the air before it reaches the field so it can no longer lift dry particles, and they shelter the crop as well. Bunds also stand above the surface and break the wind at ground level, which is why the syllabus credits them for both agents.
Keeping the soil covered. Maintaining vegetation cover, for example a cover crop between harvests or grass strips, means the leaves intercept the rain, the roots bind the particles and the plants take up water so less runs off. Adding organic matter such as manure, compost or returned crop residue binds fine particles into larger, heavier crumbs and leaves larger pores so water soaks in instead of running off.
Weighing them against each other. Terracing is the most effective on steep land and makes it farmable at all, but it is very labour-intensive to build and must be maintained, or a collapsed terrace concentrates the water instead of spreading it. Contour ploughing costs nothing beyond driving in a different direction. Wind breaks occupy land and compete with the crop at the field edge, and take years to grow. Organic matter works slowly and has to be repeated.
A judgement, not a list. A creditable judgement might be: begin with contour ploughing and a cover crop, because both are cheap, can be done this season and address the bare soil that is the immediate cause; build terraces on the steepest part over several seasons as labour allows; plant the wind break at the same time so it is established before it is needed. Any judgement is acceptable if it follows from the points made.
Support the judgement. The strongest answers say who bears the cost and over what timescale: contour ploughing is free and immediate, terracing is expensive and slow but permanent, and topsoil once lost is not replaced within a human lifetime, so the cost of doing nothing rises every year. Credit also for naming what she is trying to avoid: falling yields, silting of the river below, desertification if the land dries out and vegetation cannot re-establish, and mass movement — a landslide or mudslide — on a deforested slope saturated by the wet season.
⚠ If you missed marks here: the command word is discuss, so a list of six named strategies scores about two marks however long it is. A named strategy on its own scores one mark and no more: the marks live in the mechanism ("terracing, because a level step stops the water and lets it soak in"), in the limitation ("but it is labour-intensive and a collapsed terrace concentrates the water"), and in the judgement that follows from them. Two more traps: the question names both a wet season and a dry season, so an answer that only deals with water misses half the problem; and a judgement has to choose, so "all of them would help" is not a judgement. Finally, keep the tone technical. This is a farmer trying to keep her land productive, not a villain, and the mark scheme has no marks in it for blame. If you are stuck, work back from the one sentence that unlocks the whole sub-topic: soil is lost when it is left bare and held when it is covered.

Self-Assessment

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IGCSE Environmental Management 0680 — Paper 1 — Topic 2 Land — Challenge
For examination preparation only. Not an official Cambridge Assessment paper.