Science 8 · Unit 4: Ecosystems · Cambridge Lower Secondary Science Stage 8

Questions

1. 1. What is an invasive species?

   • a native species that is rare
   • an extinct species
   • a species only found in zoos
   • a species introduced to a new area where it spreads and causes harm
   Check

2. 2. What does 'aquatic' mean?

   • living in water
   • living in deserts
   • living in trees
   • living underground
   Check

3. 3. What is a herbivore?

   • a plant
   • a decomposer
   • an animal that eats plants
   • an animal that eats meat
   Check

4. 4. How do beavers change their habitat?

   • They plant trees.
   • They build dams that form deep, wide pools.
   • They dig deserts.
   • They make rivers flow faster.
   Check

5. 5. Why have beaver numbers increased so much in Tierra del Fuego?

   • It is too cold.
   • They eat fish.
   • They have no natural predators there.
   • People hunt them a lot.
   Check

6. 6. Why might introducing brown bears to Tierra del Fuego be a bad idea?

   • Bears don't eat anything.
   • The bears could become invasive and harm other native animals.
   • Bears would build dams too.
   • It would definitely solve the problem.
   Check

7. 7. Why are water hyacinths controlled in South America but not elsewhere?

   • There is less water.
   • South American herbivores eat them.
   • People pull them out by hand.
   • It is too cold there.
   Check

8. 8. How does water hyacinth kill native plants and fish?

   • It poisons the water.
   • It covers the water, so light and oxygen can't reach below.
   • It makes the water too hot.
   • It eats them.
   Check

9. 9. How does water hyacinth harm fishing on Lake Victoria?

   • It cleans the nets.
   • It makes fish bigger.
   • Boats can't move through it and nets catch hyacinth, not fish.
   • It attracts more fish.
   Check

10. 10. Why were cane toads brought to Australia in 1935?

    • as pets
    • to eat beetles that were destroying sugar cane
    • to pollinate flowers
    • to eat rabbits
    Check

11. 11. Why do cane toads harm Australian predators?

    • They are too big to eat.
    • They eat the predators.
    • The toads are poisonous and kill predators that eat them.
    • They carry the predators away.
    Check

12. 12. Why have cane toad numbers stayed constant in South America?

    • They have predators there that control their numbers.
    • There is no food.
    • It is too hot.
    • They are hunted by people only.
    Check

13. 13. Why do scientists feed quolls cane toad sausages that make them vomit?

    • to teach quolls to avoid eating cane toads
    • to fatten them
    • to kill them
    • to help them grow
    Check

14. 14. How could you test whether the sausage training works?

    • compare survival of trained and untrained quolls in areas with cane toads
    • count cane toads in South America
    • feed quolls only fruit
    • measure the temperature
    Check

15. 15. What is a native species?

    • one brought from another country
    • one that lives naturally in an area
    • one that is extinct
    • one that only lives in labs
    Check

16. 16. Why were stoats brought to New Zealand?

    • to pollinate flowers
    • to control the rabbits
    • to be farmed for wool
    • to eat the rats
    Check

17. 17. Why were New Zealand's native birds, such as the kiwi, so easily harmed by introduced animals?

    • The birds only lived in trees.
    • There was no food for the birds.
    • There were no predatory mammals there before humans arrived.
    • The birds were too big to hide.
    Check

18. 18. What does 'eradicate' mean?

    • to get rid of completely
    • to breed quickly
    • to protect from harm
    • to introduce to a new place
    Check

19. 19. Buffelgrass was planted in Arizona as cattle food and is now spreading through the Sonoran Desert. What kind of species is it there?

    • an introduced (invasive) species
    • an extinct species
    • a decomposer
    • a native species
    Check