← Back to the activity

Class 8 Science — Ecosystems and food chains

Separate the living and non-living parts of a habitat, build a food chain, and name the three ways two organisms can live together.

Name: ________________________

  1. 1.The decomposers vanish from a forest overnight. What follows?

    • a) Dead matter piles up and nutrients stop returning to the soil
    • b) Nothing changes, since decomposers do no work in a forest
    • c) The soil becomes richer, since nothing is taking nutrients out of it
    • d) The plants grow faster, since nothing is breaking anything down

  2. 2.Match each pair of organisms to the kind of relationship they have.

    • Honeybees and flowers
    • An orchid on a tree branch
    • A tick on a dog
    • parasitism
    • mutualism
    • commensalism

  3. 3.Sort these ecosystems by whether they sit in water or on land.

    Groups: Aquatic ecosystem · Terrestrial ecosystem

    • Grassland
    • A pond
    • A forest
    • A river

  4. 4.Sort what you would find in a pond or a forest by whether it is living or not.

    Groups: Biotic · Abiotic

    • Grass
    • Sunlight
    • Water
    • Fish
    • Soil

  5. 5.Food chains in an ecosystem are not really separate. What are they, taken together?

    • a) A community, because the chains share a habitat
    • b) A food web, because an organism may be eaten by two or more kinds of organism
    • c) A population, because the chains hold organisms of the same kind
    • d) A trophic level, because each chain occupies one level

  6. 6.In the chain grass → grasshopper → frog → snake, the frogs disappear. What happens to the grasshoppers and the snakes?

    • a) Both increase, because one fewer animal is competing for space
    • b) Both stay the same, because the grass is unaffected
    • c) Grasshoppers decrease and snakes increase
    • d) Grasshoppers increase, because nothing is eating them; snakes decrease, because their food has gone

  7. 7.Sort these animals by what they eat.

    Groups: Herbivore · Carnivore · Omnivore

    • Leopard
    • Mouse
    • Hare
    • Crow
    • Deer
    • Fox

  8. 8.Put these four levels of nature in order, from the smallest upwards.

    • Community
    • Individual
    • Population
    • Ecosystem

Answer key — Class 8 Science — Ecosystems and food chains

  1. 1. a) Dead matter piles up and nutrients stop returning to the soil
  2. 2. Honeybees and flowers → mutualism; An orchid on a tree branch → commensalism; A tick on a dog → parasitism
  3. 3. A pond → Aquatic ecosystem; A river → Aquatic ecosystem; A forest → Terrestrial ecosystem; Grassland → Terrestrial ecosystem
  4. 4. Fish → Biotic; Grass → Biotic; Soil → Abiotic; Sunlight → Abiotic; Water → Abiotic
  5. 5. b) A food web, because an organism may be eaten by two or more kinds of organism
  6. 6. d) Grasshoppers increase, because nothing is eating them; snakes decrease, because their food has gone
  7. 7. Deer → Herbivore; Hare → Herbivore; Leopard → Carnivore; Crow → Omnivore; Fox → Omnivore; Mouse → Omnivore
  8. 8. 1. Individual 2. Population 3. Community 4. Ecosystem