IGCSE Environmental Management Paper 1 — Topic 3 Water — Challenge

Principles of Environmental Management — Topic 3 Challenge

Duration45 minutes

Total Marks40

Questions7

Time Remaining45:00

Syllabus0680

This paper covers the whole of Topic 3. The questions are not in syllabus order and they are not one question per sub-topic. Material from 3.1 to 3.6 is mixed across every question, exactly as Cambridge mixes it, so do not expect Question 1 to be about 3.1.

Instructions

Answer all questions in the spaces provided.
Show all working for calculations.
The number of marks is given in brackets at the end of each part.
Give non-exact answers to 3 significant figures unless the question says otherwise.
Your answers will be automatically graded when you submit, then you check each mark yourself against the mark scheme.

Question Navigation

Question 1 — Water in the cycle, and getting it to a tap

Total: 6 marks

(a)[1]

Define the term potable water.

Model Answer — 1(a)

water that is safe to drink

the idea of safe to drink is what is credited

"clean water" or "pure water" on its own does not score. Water can be clean of visible dirt and still carry the bacteria that cause cholera

⚠ If you missed marks here: potable is a definition mark, so it is marked for one exact idea. Learn the syllabus wording and write it: water that is safe to drink. Note also that potable water is not chemically pure water; treated tap water still contains dissolved ions, and that is fine.

water that is safe to drink

(b)[2]

In the water cycle, name the transfer in which water is caught and held on the leaves of vegetation before it reaches the ground, and name the transfer in which water soaks downwards from the ground surface into the soil.

Model Answer — 1(b)

interception (water held on vegetation)

infiltration (water soaking into the soil from the surface)

do not accept precipitation for the first: precipitation is water arriving from the atmosphere as rain, snow or hail. Interception is what happens to it on the way down

do not accept through-flow or ground water flow for the second: both are sideways movement once the water is already underground

⚠ If you missed marks here: interception and precipitation are the pair that gets mixed up most often in this topic. Precipitation is the journey out of the atmosphere; interception is the pause on the leaves. They are two different named transfers and the syllabus lists them separately, so one word cannot earn the other mark. Infiltration is into the soil; through-flow is sideways through it.

interception infiltration

(c)[2]

State the four stages used to treat water so that it is potable, in the correct order.

Model Answer — 1(c)

screening, then sedimentation, then filtration, then chlorination

1 mark for the first two named in that order, 1 mark for the second two named in that order

the order carries the marks. Chlorination must come last, because there is no point killing the bacteria and then stirring the water through unfiltered grit

⚠ If you missed marks here: this is an ordered chain and ordered chains are marked in order. A common slip is putting filtration before sedimentation. Sedimentation lets the heavy particles settle out under gravity first, so that the filter is not immediately clogged; filtration then takes out the fine material the settling missed.

screening then sedimentation, in that order filtration then chlorination, in that order

(d)[1]

Name the ocean that lies around the North Pole.

Model Answer — 1(d)

Arctic Ocean

the five oceans named by the syllabus are Pacific, Atlantic, Indian, Southern and Arctic

⚠ If you missed marks here: Arctic and Southern are the two that get swapped. Arctic is at the North Pole; Southern is the one that rings the continent at the South Pole. If you learn them as a pair, one reminds you of the other.

Arctic Ocean

Question 2 — Desalination and multipurpose dams

Total: 6 marks

(a)[3]

Describe the process of reverse osmosis.

Model Answer — 2(a)

the salt water is put under high pressure

it is forced through a membrane

the membrane lets water molecules pass through but stops most ions and other molecules, so the water leaving is potable

all three marking points are in the syllabus wording of 3.1.7(b); the mark scheme is looking for pressure, membrane and selective passage

⚠ If you missed marks here: the third mark is the one usually lost. It is not enough to say the membrane "filters the salt out". Say what gets through and what does not: water molecules pass, most ions and other molecules do not. That sentence is the whole reason the method works.

water is put under high pressure passed through a membrane membrane allows water molecules through but stops most ions and other molecules

(b)[1]

State one way in which distillation separates the water differently from reverse osmosis.

Model Answer — 2(b)

distillation separates by boiling point: the water is heated until it boils, the salt stays behind in the liquid and the steam is pure water, which is then cooled and condensed

reverse osmosis separates by molecule size at a membrane and uses pressure rather than heat

either half of that contrast, correctly stated, scores the mark

⚠ If you missed marks here: the two methods are not two names for the same thing. Distillation uses heat and a change of state; reverse osmosis uses pressure and never boils anything. If your answer would still be true with the two words swapped, it is not yet an answer.

distillation separates by boiling point and uses heat, whereas reverse osmosis separates by molecule size and uses pressure

(c)[2]

A dam is described as a multipurpose dam. State two uses of a multipurpose dam other than the storage of water.

Model Answer — 2(c)

any 2 from:

flood control

hydro-electric power

irrigation

transport

recreation

tourism

fish farming

storage of water is excluded by the question, so it earns nothing here

⚠ If you missed marks here: recreation and tourism are two separate uses in the syllabus list and both are creditable, but a marker will not award the same idea twice. If you write "people can visit it" and "tourists come", that is one mark, not two. Pick two clearly different uses from the list.

one correct use of a multipurpose dam other than water storage a second, different correct use

Question 3 — Water pollution and its effects

Total: 6 marks

(a)[2]

State two sources of water pollution.

Model Answer — 3(a)

any 2 from: domestic waste; sewage; plastic waste; industrial processes; agricultural practices

"factories" is accepted for industrial processes and "farming" for agricultural practices

"rubbish" is too vague on its own; say domestic waste or plastic waste

⚠ If you missed marks here: domestic waste and sewage are counted as two different sources by the syllabus, so both can score. But two versions of the same idea, such as "sewage" and "human waste from toilets", will only be credited once.

one correct source of water pollution a second, different correct source

(b)[3]

Fertiliser containing nitrate is applied to fields beside a river. Explain how this leads to eutrophication in the river.

Model Answer — 3(b)

nitrate is leached from the soil and carried into the river, so the water becomes enriched with nutrients

the extra nutrients cause rapid growth of algae at the surface, which blocks the light, so the plants below cannot photosynthesise and they die

the dead material is broken down by decomposers, whose respiration uses up the dissolved oxygen, so organisms that need oxygen die

the marks are for the chain, not for the word eutrophication itself

⚠ If you missed marks here: the last link is the one people leave out. It is not the algae that kill the fish; it is the bacteria decomposing the dead plants, because their respiration takes the oxygen out of the water. If your answer stops at "the algae block the light" you have written two thirds of the chain and earned two thirds of the marks.

nitrate leaches into the water, enriching it with nutrients algal growth blocks light so plants below die decomposers use up dissolved oxygen so organisms die

(c)[1]

State one effect of acid rain on organisms in rivers and lakes.

Model Answer — 3(c)

the pH of the water falls, so organisms that cannot tolerate the lower pH die

accept: fish eggs fail to develop; numbers of organisms fall; species are lost from the lake

accept: aluminium ions are released from the surrounding soil into the water and damage the gills of fish

⚠ If you missed marks here: the question asks about organisms, so an answer about buildings or about trees on the hillside does not score. Tie the answer to something living in the water.

a correct effect of acid rain on organisms living in rivers or lakes

Question 4 — Water related diseases

Total: 5 marks

(a)[3]

Describe how mosquitoes spread malaria between people.

Model Answer — 4(a)

the female Anopheles mosquito is the vector

the malaria Plasmodium parasite is passed into a person when that person is bitten by an infected mosquito

the parasite is passed back to non infected mosquitoes when they feed on the blood of an infected human

the third point is the return leg, and it is a separate syllabus statement, 3.3.1(c)

⚠ If you missed marks here: almost everyone writes the first two points and stops. The syllabus states three things and the third is that the parasite travels back into uninfected mosquitoes when they bite an infected person. Without that leg the cycle does not continue, which is exactly why an examiner asks for it. Write the loop, not the arrow.

female Anopheles mosquito is the vector Plasmodium parasite passed to a human bitten by an infected mosquito parasite passed to non infected mosquitoes that feed on the blood of an infected human

(b)[2]

State two strategies used to control cholera.

Model Answer — 4(b)

any 2 from: handwashing; adequate sanitation and sewage treatment; a potable water supply by boiling or chlorination; vaccination

these are the four listed in 3.3.3 and the mark scheme will not go beyond them

⚠ If you missed marks here: do not answer this one with malaria control. Nets, repellent and draining breeding sites do nothing about cholera, which is spread through water contaminated with sewage rather than by a biting insect. The two diseases have separate control lists and the examiner is checking that you know which list is which.

one correct cholera control strategy a second, different correct cholera control strategy

Question 5 — Oil pollution of marine and coastal ecosystems

Total: 5 marks

(a)[2]

State two causes of oil pollution of marine ecosystems, other than a shipping accident.

Model Answer — 5(a)

any 2 from: off shore oil extraction; on shore oil extraction; pipelines; the cleaning of tanks at sea; refineries

off shore and on shore extraction count as one idea unless the answer makes the difference clear

⚠ If you missed marks here: the routine sources matter as much as the dramatic ones. Cleaning tanks at sea and leaking pipelines release oil steadily rather than all at once, and the syllabus lists them for that reason. An answer that gives only accidents has missed the point of the objective.

one correct cause other than a shipping accident a second, different correct cause

(b)[1]

State one strategy used to prevent oil spills.

Model Answer — 5(b)

MARPOL, the International Convention for the Prevention of Pollution from Ships

double hulled oil tankers

risk assessments

regular maintenance

⚠ If you missed marks here: prevention and clean up are two different objectives here. Booms, sorbents, skimmers, detergent sprays and controlled burning are all ways of minimising the impact of a spill that has already happened, so none of them answers a prevention question.

one correct oil spill prevention strategy

(c)[2]

Explain how booms and sorbents reduce the impact of an oil spill.

Model Answer — 5(c)

booms float on the surface and surround the slick, so the oil is contained in one place and cannot spread to the shore

sorbents soak up the oil, so the oil can be lifted out of the water and removed rather than left in the ecosystem

1 mark for each, and each mark needs the mechanism, not just the name

⚠ If you missed marks here: an explain question needs a because or a so that. "Booms stop the oil" names the equipment without saying what it does; "booms float around the slick so the oil is held in one place and does not reach the shore" is the same length and earns the mark.

booms float and contain the slick so it does not spread to the shore sorbents soak up the oil so that it can be removed from the water

Question 6 — Plastics in the marine environment

Total: 4 marks

(a)[2]

A student writes: "All bioplastics rot away in the soil, so bioplastics cannot pollute."
Explain why this statement is not correct.

Model Answer — 6(a)

bioplastics can be biodegradable or non biodegradable, so not all of them decompose

the word bio describes what the plastic is made from, namely biological raw materials, fully or partly, instead of fossil fuels. It does not describe what happens to the plastic afterwards

accept as a third route to the second mark: biodegradable plastics decompose at different rates depending on biotic and abiotic factors, so even a biodegradable one may persist

⚠ If you missed marks here: this is the single most common misreading in 3.6. Bioplastic is a statement about the raw material; biodegradable is a statement about the fate. A plastic can be made from plant material and still be non biodegradable, and a plastic made from fossil fuels can be designed to be biodegradable. Keep the two ideas in separate boxes in your head.

bioplastics may be biodegradable or non biodegradable bio refers to being made from biological raw materials rather than fossil fuels, not to decomposing

(b)[2]

Describe what is meant by microplastics.

Model Answer — 6(b)

plastics that are less than 5 mm in length

formed when larger plastics break down, and also used deliberately in commercial products

the size figure is required for the first mark

⚠ If you missed marks here: "very small pieces of plastic" does not score, because the syllabus gives a number and the number is the mark. Write less than 5 mm. The second mark needs an origin, and there are two: fragments of larger plastic, and microplastics manufactured into products in the first place.

plastics less than 5 mm in length formed when larger plastics break down, or used in commercial products

Question 7 — Managing the harvesting of marine species

Total: 8 marks

(a)[2]

Define marine aquaculture and state the three groups of organism that the syllabus includes within it.

Model Answer — 7(a)

the farming of marine species in captivity

fish, crustaceans and seaweeds

all three groups are needed for the second mark

⚠ If you missed marks here: the phrase in captivity is doing real work in this definition and is often dropped. Catching wild organisms from the sea is fishing; growing them under human control is aquaculture. Note also that seaweeds count, so an answer only about animals is incomplete.

farming of marine species in captivity fish, crustaceans and seaweeds

(b)[6]

Discuss the benefits and limitations of strategies for the management of the harvesting of marine species.

Model Answer — 7(b)

this is a levels style question. Award up to 4 marks for benefits and limitations, at least one of each, then up to 2 for a judgement that is supported by what has gone before.

Benefits, any of:

quotas, closed seasons and limits on the number of fishing days cap the catch, so the stock has time to breed and future catches can be maintained

an increased mesh size lets young organisms escape the net, so they survive to reproduce, and it also reduces the bycatch of species that were not being targeted

sustainable methods such as pole and line take one organism at a time, so bycatch is almost eliminated and the sea bed is not disturbed

protected areas and conservation laws shelter the whole food chain rather than the target species alone, so the ecosystem that supports the fishery is kept intact

international agreements matter because stocks move across borders, and a rule that stops at a national boundary does not protect a stock that does not

Limitations, any of:

the income of fishing communities falls in the short term, and the people who lose that income are usually not the people who benefit from the recovered stock years later

monitoring and enforcement are expensive, and at sea and beyond national waters they are extremely hard, so a rule that is not enforced changes nothing

quotas can push boats to discard undersized or over quota catch dead over the side, so the organisms are killed anyway and never appear in the figures

limits on boat and net size can be worked around, for example by more boats or more trips

an international agreement binds only the countries that sign it and can be left

Judgement, up to 2 marks:

a judgement that names what the decision actually turns on, for example that these strategies work only where monitoring and enforcement exist, so the limiting factor is capacity to enforce rather than the choice of rule

a judgement that separates who gains from who pays, and over what timescale: the cost falls on this year’s fishing community, the benefit falls on a future one

a bare conclusion such as "so they are good" with nothing behind it scores 0 of the 2

⚠ If you missed marks here: two things cost marks here. The first is imbalance: three paragraphs of benefits and one line of limitations is not a discussion, and the mark scheme caps you. The second is stopping before the judgement. The last 2 marks are not for more content, they are for saying what the decision turns on. Use the frame from the Challenge Prep guide: benefit, limitation, who bears the cost, over what timescale, judgement.

one clear benefit of a named management strategy, with a reason a second, different benefit, with a reason one clear limitation, with a reason a second, different limitation, with a reason a judgement is reached, not just a list the judgement is supported by the points already made, naming who bears the cost or over what timescale

Self-Assessment

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