1.3.3

Changes to Food Webs

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Changes to Food Webs - Plants

A food chain is a model that shows how energy flows through an ecosystem. A food chain shows which organisms eat other organisms. A food web is a series of food chains that overlap.

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Predator-prey relationships

  • Predator and prey numbers will change over time.
  • An increase in predators will lead to a decrease in prey organisms.
    • Prey numbers will decrease because there are more predators to eat the prey.
  • A decrease in predators will lead to an increase in prey organisms.
    • Prey numbers will increase because there are fewer predators to eat the prey.
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Plants competing for light

  • Competition between plants can occur above and below the ground.
  • Plants compete for light.
    • Plants need light for photosynthesis.
    • Plants grow tall and spread their leaves to maximise the amount of the light they receive.
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Plants competing for water

  • Plants compete for water.
    • Plants need water for photosynthesis.
    • Plants can spread their roots deeper to find water.
    • Plants can spread along the surface of the soil to absorb the water from rainfall.
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Nutrients and space

  • Plants compete for nutrients.
    • Plants absorb nutrients via their roots.
  • Plants compete for space.
    • Plants need space to grow.

Changes to Food Webs - Animals

Animals compete with one another. Animals compete for food. Animals compete to reproduce. Animals compete for space.

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Animals competing for food

  • Competition occurs in animals of the same and different species.
  • Animals compete for food.
    • Animals need food to get nutrients and glucose.
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Animals competing to reproduce

  • Animals compete to reproduce.
    • Animals need to reproduce to pass on their DNA to their offspring.
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Animals competing for space

  • Animals compete for space.
    • Animals often compete for territory.
    • Competition for territory can be intraspecific and interspecific.

Changes to Food Webs - Factors

Abiotic and biotic factors affect organisms. Abiotic factors are non-living factors. Biotic factors are living factors.

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Abiotic factors

  • Abiotic factors affect the population of organisms in an ecosystem.
    • Abiotic factors are non-living factors.
  • Light is an abiotic factor.
    • Plants need light for photosynthesis.
  • Temperature is an abiotic factor.
    • Organisms can adapt to live in hot or cold environments.
    • Moisture is an abiotic factor.
    • Plants need moisture.
    • Plants can also become overwatered.
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pH

  • pH is an abiotic factor.
    • Plants are adapted to grow in acidic or alkaline soils.
    • Fish are also adapted to live in waters with specific pHs.
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Gases

  • Carbon dioxide and oxygen are abiotic factors.
    • Plants need carbon dioxide for photosynthesis.
    • Plants and animals need oxygen for respiration.
  • Carbon dioxide-rich environments lack oxygen.
    • Organisms might not be able to survive in carbon dioxide-rich environments.
    • Freshwater species are adapted to survive at certain oxygen levels.
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Biotic factors

  • Biotic factors affect the population of organisms in an ecosystem.
    • Biotic factors are living factors.
  • New predators are a biotic factor.
    • New predators may outcompete existing predators.
  • Disease is a biotic factor.
    • The spread of disease can wipe out a community if it has not built up immunity.
  • Food is a biotic factor.
    • Organisms need nutrients to survive.

Jump to other topics

1Biology

1.1Cells, Tissues & Organs

1.2Reproduction & Variation

1.3Ecological Relationships & Classification

1.4Digestion & Nutrition

1.5Plants & Photosynthesis

1.6Biological Systems & Processes

2Chemistry

2.1Particles

2.2Chemical Reactions

2.3Atoms, Elements, Compounds

2.4The Periodic Table

2.5Materials & the Earth

2.6Reactivity

2.7Energetics

2.8Properties of Materials

3Physics

3.1Energy

3.2Forces & Motion

3.3Waves

3.4Electricity & Magnetism

3.5Matter

3.6Space Physics

4Thinking Scientifically

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