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

Questions

1. 1. What is an ecosystem?

   • a single habitat with no living things
   • only the animals in an area
   • the living things in an area and their non-living environment, interacting together
   • just the plants in an area
   Check

2. 2. What is a habitat?

   • the food an organism eats
   • an organism's offspring
   • the place where an organism lives
   • a type of cell
   Check

3. 3. Describe the habitat of the saguaro cactus.

   • deep ocean
   • hot, dry desert where it rarely rains
   • cold mountain tops
   • wet rainforest
   Check

4. 4. How do the saguaro's roots help it survive?

   • They grow very deep to find rivers.
   • They absorb sunlight.
   • They spread widely just below the surface to capture rain quickly.
   • They store fat.
   Check

5. 5. Why does the saguaro have no leaves?

   • Water would evaporate from leaves and the plant would dry out.
   • Leaves are too heavy.
   • Animals eat leaves first.
   • It can't make leaves.
   Check

6. 6. Without leaves, how does the saguaro make food?

   • it doesn't need food
   • by eating insects
   • by photosynthesis in its green stems
   • by absorbing food from soil
   Check

7. 7. Why can't saguaros grow on high mountains?

   • There are no animals.
   • The soil is too sandy.
   • It is too cold; their cells die if they freeze.
   • There is too much sunlight.
   Check

8. 8. What protects the saguaro from being eaten?

   • soft stems
   • a sweet smell
   • sharp spines
   • bright flowers
   Check

9. 9. Which animal pollinates saguaro flowers?

   • desert tortoises
   • elf owls
   • Harris hawks
   • bats
   Check

10. 10. What would happen to elf owls if all Gila woodpeckers and gilded flickers died out?

    • They would lose nest holes, since they use old woodpecker holes.
    • They would grow bigger.
    • Nothing would change.
    • They would have more food.
    Check

11. 11. What would happen if all saguaro cacti died out?

    • Nothing would change.
    • Many species would lose food and nesting places.
    • More animals would live there.
    • Bats would have more food.
    Check

12. 12. Why don't saguaros grow in wetter parts of Arizona?

    • Other plants grow better there and outcompete them.
    • Water kills all cacti instantly.
    • Bats live there.
    • There is no sunlight.
    Check

13. 13. Where do Harris hawks nest?

    • on the sand
    • in holes underground
    • in nests of sticks where the cactus arms branch
    • in old woodpecker holes only
    Check

14. 14. Which animals eat saguaro fruits?

    • only insects
    • birds, mammals and reptiles like desert tortoises
    • only fish
    • nothing eats them
    Check

15. 15. How long can saguaro cacti live?

    • about 20 years
    • about 2 years
    • about 2000 years
    • about 200 years
    Check

16. 16. Why do cactus wrens build their nests in the very spiky teddy bear cholla cactus?

    • Its flowers feed the young birds.
    • It gives them water to drink.
    • It is the warmest place in the desert.
    • Few predators will get close to it.
    Check

17. 17. Why are many desert animals, like kangaroo rats, nocturnal?

    • because there is more rain at night
    • to avoid overheating and drying out in the day
    • to see their food more easily
    • because plants only grow at night
    Check

18. 18. What is the difference between an ecosystem and a habitat?

    • A habitat has living things; an ecosystem has only non-living things.
    • An ecosystem is one organism's home; a habitat is a whole desert.
    • A habitat is where an organism lives; an ecosystem is all the interactions between the organisms and their surroundings.
    • They mean the same thing.
    Check