# Food Supply and Habitat Destruction

> Biology · CIE IGCSE 0610
> Source: https://www.owlsprep.com/study/cie-0610-u15-food-supply-and-habitat-destruction/

This guide covers CIE IGCSE Biology 0610 syllabus 20.1 (how humans increase food production, plus the advantages and disadvantages of monocultures and intensive livestock) and 20.2 (biodiversity and habitat destruction). All content on this page is Core.

**Prerequisites:** [Basic understanding of ecosystem structure and trophic levels](https://www.owlsprep.com/study/cie-0610-u14-ecosystem-structure/); [Knowledge of food chains and food webs](https://www.owlsprep.com/study/cie-0610-u14-energy-flow-food-chains-food/)

## Learning objectives

- Describe how humans have increased food production: agricultural machinery, chemical fertilisers, insecticides, herbicides and selective breeding
- Describe the advantages and disadvantages of large-scale monocultures of crop plants and of intensive livestock production
- Describe the reasons for habitat destruction and explain the undesirable effects of deforestation

## Core: How Humans Increase Food Production

As the human population grows, more food is needed. Syllabus 20.1 requires you to describe five specific ways humans have increased food production. Learn all five and how each one raises the quantity or quality of food produced.

- **Agricultural machinery** (e.g. tractors, combine harvesters): allows much larger areas of land to be farmed and improves the efficiency of sowing, treating and harvesting crops
- **Chemical fertilisers**: add mineral ions such as nitrate, phosphate and potassium to the soil to improve crop yields
- **Insecticides**: kill insect pests that eat or damage crops, improving the quality and yield of the crop
- **Herbicides**: kill weeds so that crop plants face less competition for light, water and mineral ions
- **Selective breeding**: breeding crop plants and livestock that have desired features (e.g. high yield, disease resistance) over several generations to improve production

**Monoculture** — The large-scale cultivation of a single crop species in the same area of land, such as a field growing only wheat or only oil palm.

Monocultures make farming efficient, but growing only one crop species over a large area has clear trade-offs (syllabus 20.1.2):

- **Advantages**: machinery can be used efficiently over large uniform areas; a single crop is easier to sow, manage and harvest; produces a high yield of one valuable crop
- **Disadvantages**: low biodiversity, as few other species can live there; pests and diseases spread rapidly through the uniform crop; the same mineral ions are removed from the soil each year, so more fertiliser is needed

Intensive livestock production keeps animals in controlled, often crowded, conditions to maximise food output. Its advantages and disadvantages are also examinable (syllabus 20.1.3):

- **Advantages**: more meat, eggs or milk produced in a smaller area and in less time; food is cheaper for consumers; restricting movement and keeping animals warm means less energy is lost, so more food energy is converted into body mass (higher efficiency)
- **Disadvantages**: raises animal-welfare concerns; diseases spread easily in crowded conditions, often leading to routine antibiotic use and the risk of antibiotic resistance; large amounts of animal waste can pollute the surrounding environment

**Worked example:** Describe two advantages and two disadvantages of growing a large-scale monoculture of a single crop such as wheat.

1. Advantages: 1. Machinery (e.g. combine harvesters) can be used efficiently across the whole uniform field, reducing labour and cost. 2. A high yield of one valuable crop is produced, which is easy to harvest and sell.
2. Disadvantages: 1. Biodiversity is low because few other plant or animal species can live in a field of a single crop. 2. Pests and diseases that attack wheat can spread quickly through the whole crop, and the same mineral ions are removed from the soil each year, so more fertiliser is required.

> **Exam tip:** For 20.1, memorise the five named methods (machinery, chemical fertilisers, insecticides, herbicides, selective breeding). When asked to evaluate monoculture or intensive livestock, always give both advantages and disadvantages.

## Core: Biodiversity and Habitat Destruction

Biodiversity is the number of different species that live in an area (syllabus 20.2.1). Human activity often destroys habitats, reducing biodiversity and disrupting ecosystems.

**Habitat destruction** — The damaging of a natural habitat so that it can no longer support the species that normally live there, often leading to local extinction of those species.

The syllabus (20.2.2) gives three reasons for habitat destruction:

- Increased area for housing, crop plant production and livestock production (e.g. clearing forests and draining land for farms and settlements)
- Extraction of natural resources (e.g. mining and quarrying, and logging for timber)
- Freshwater and marine pollution, which damages aquatic habitats

Humans can also harm habitats indirectly: by altering food webs and food chains (for example through overharvesting a species), humans can have a negative impact on the whole habitat (syllabus 20.2.3).

Deforestation is a key example of habitat destruction. You must be able to explain its undesirable effects (syllabus 20.2.4): reducing biodiversity, extinction of species, loss of soil (erosion), flooding, and an increase of carbon dioxide in the atmosphere.

**Worked example:** Explain three undesirable effects of large-scale deforestation.

1. 1. Reduced biodiversity and extinction: trees provide food and shelter for many species, so removing them destroys habitats and can drive species to local or complete extinction, lowering biodiversity.
2. 2. Loss of soil and flooding: tree roots bind the soil and their leaves reduce the impact of rain, so without trees the soil is easily washed away (erosion), and water runs off the land quickly, increasing the risk of flooding.
3. 3. Increased atmospheric carbon dioxide: fewer trees remove less CO2 by photosynthesis, and burning or decay of the felled trees releases stored carbon as CO2, contributing to the enhanced greenhouse effect.

> **Exam tip:** For deforestation, the five mark-scheme effects are: reducing biodiversity, extinction, loss of soil, flooding, and increase of CO2. Always link the cause directly to the effect, e.g. 'roots bind soil, so removing trees leads to soil erosion'.

## Core: Structured Exam Practice

Practise writing full answers to these exam-style questions to reinforce your knowledge, as the exam includes structured response questions worth 3-8 marks.

**Check your understanding**

1. State three ways humans have increased food production.

   *Why:* Stick to the five named syllabus methods; do not invent extra factors such as 'better weather' or 'more workers'.

2. Explain one way habitat destruction reduces biodiversity.

   *Why:* Always link the change in habitat directly to the impact on species to get full marks.

3. State two advantages of intensive livestock production.

   *Why:* Do not confuse advantages with disadvantages; welfare and disease spread are disadvantages, not advantages.

## Common pitfalls

- **Wrong:** Listing vague or invented ways humans increase food production instead of the five named syllabus methods.
  - Why it fails: Mark schemes for 20.1.1 credit only the five listed methods: agricultural machinery, chemical fertilisers, insecticides, herbicides and selective breeding.
  - Correct: Memorise the five methods and how each raises yield or quality; do not write general answers like 'farming more land' without naming machinery.
- **Wrong:** Giving vague impacts of habitat destruction without explanation, e.g. 'deforestation harms animals'.
  - Why it fails: Exam mark schemes require a clear causal link between the human activity and the impact to award full marks.
  - Correct: Structure impacts as 'X activity causes Y change to the habitat, which leads to Z effect on species/ecosystem'.
- **Wrong:** Only giving advantages (or only disadvantages) when asked to describe both for monoculture or intensive livestock.
  - Why it fails: These questions (20.1.2, 20.1.3) require both sides, so a one-sided answer loses half the marks.
  - Correct: Plan at least two advantages and two disadvantages before writing your answer.
- **Wrong:** Confusing habitat destruction with pollution in exam answers.
  - Why it fails: Pollution is one cause of habitat destruction, but they are separate ideas, and mislabelling loses marks.
  - Correct: State the three syllabus reasons for habitat destruction: increased area for housing/crop/livestock, extraction of natural resources, and freshwater/marine pollution.
- **Wrong:** Forgetting one of the five undesirable effects of deforestation.
  - Why it fails: Structured questions on deforestation often expect several distinct effects; missing one caps your marks.
  - Correct: Recall all five: reducing biodiversity, extinction, loss of soil, flooding, and increase of atmospheric CO2.

## Cheatsheet

| Topic | Core Content (all candidates) |
| --- | --- |
| Increasing food production (20.1.1) | Agricultural machinery, chemical fertilisers, insecticides, herbicides, selective breeding |
| Monoculture (20.1.2) | Advantages: efficient machinery use, high yield of one crop. Disadvantages: low biodiversity, rapid pest/disease spread, soil nutrient depletion |
| Intensive livestock (20.1.3) | Advantages: more/cheaper food, higher energy efficiency. Disadvantages: welfare concerns, disease spread/antibiotics, waste pollution |
| Habitat destruction (20.2.2) | Reasons: area for housing/crops/livestock, resource extraction, freshwater/marine pollution |
| Deforestation effects (20.2.4) | Reducing biodiversity, extinction, loss of soil, flooding, increase of atmospheric CO2 |

## What's next

Now that you have covered how humans increase food production and the causes and effects of habitat destruction for CIE IGCSE Biology 0610, move on to the next sub-topic in the Human Influences on Ecosystems unit: pollution and conservation. There you will study the effects of sewage, excess fertiliser and plastics, the enhanced greenhouse effect, and how forests and fish stocks are conserved. Revising food chains and food webs from the previous unit will also help, as cross-topic questions on how humans disrupt ecosystems are common. Finally, practise structured exam questions on this topic so you can write clear, mark-scheme-aligned answers under timed conditions.

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