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

Questions

1. 1. What are decomposers?

   • predators at the top of food chains
   • plants that make food
   • organisms like fungi that break down dead material
   • animals that eat plants
   Check

2. 2. What do decomposers release into the soil?

   • nutrients that help plants grow
   • sunlight
   • plastic
   • oxygen only
   Check

3. 3. What are the conditions in a tropical rainforest?

   • freezing all year
   • always hot with plenty of rainfall
   • cold and dry
   • hot with no rain
   Check

4. 4. What is a hydrothermal vent?

   • a hot spring in a desert
   • a cave in a mountain
   • a volcano on land
   • an opening in the deep sea bed where hot water rushes out
   Check

5. 5. Why can't plants live at a hydrothermal vent?

   • There is no water.
   • It is completely dark, so there is no light for photosynthesis.
   • There is too much oxygen.
   • It is too cold.
   Check

6. 6. What are the producers at a hydrothermal vent?

   • crabs
   • bacteria
   • plants
   • tube worms
   Check

7. 7. Where do vent bacteria get their energy?

   • from the air
   • from chemicals dissolved in the hot water
   • from eating crabs
   • from sunlight
   Check

8. 8. Which is a food chain at a hydrothermal vent?

   • plants → fish → shark
   • crab → sea anemone → zooplankton → bacteria
   • bacteria → zooplankton → sea anemone → crab
   • sunlight → bacteria → tree
   Check

9. 9. How do giant tube worms and some bacteria help each other?

   • They don't interact.
   • The worms eat all the bacteria.
   • The worms give the bacteria a home; the bacteria make food for the worms.
   • The bacteria eat the worms.
   Check

10. 10. Name two habitats in the hydrothermal vent ecosystem.

    • deserts and mountains
    • lakes and rivers
    • inside tube worms and bacterial mats on the sea floor
    • tree tops and caves
    Check

11. 11. Why do baby fish live among mangrove roots?

    • to be safe from predators like larger fish
    • to eat the roots
    • to find sunlight
    • to lay eggs on land
    Check

12. 12. Look at the table (mass of fish in kg per km² of reef). Yellowtail: 6715 near mangroves, 3098 without. What does this suggest?

    • Fish avoid mangroves.
    • Mangroves reduce fish.
    • Mangroves increase the mass of fish on nearby reefs.
    • Mangroves make no difference.
    Check

13. 13. Look at the table. Which fish had the largest mass on reefs where there are mangroves on the shore?

    • blue-striped grunt
    • striped parrotfish
    • yellowtail
    • schoolmaster
    Check

14. 14. Why might reefs near mangroves have more fish?

    • Fish are added by people.
    • Mangroves make the water colder.
    • Mangroves eat predators.
    • Young fish survive in the mangroves and then move to the reef.
    Check

15. 15. What temperature can water reach where it pours out of a vent?

    • about 0 °C
    • about 400 °C
    • about 4 °C
    • about 40 °C
    Check

16. 16. Look at the table. For every fish, how do reefs without mangroves compare with reefs with mangroves?

    • They have a larger mass of fish.
    • They have no fish at all.
    • They have the same mass of fish.
    • They have a smaller mass of fish.
    Check

17. 17. In the Arctic Ocean, what grows on the underside of the sea ice?

    • grass
    • tiny algae
    • rice plants
    • mangrove roots
    Check

18. 18. Is a rice paddy a natural ecosystem?

    • No, nothing lives in it.
    • Yes, it formed by itself.
    • Yes, nobody looks after it.
    • No, it is farmed by people.
    Check

19. 19. Which apparatus catches small animals, like beetles, that run over the ground?

    • a pitfall trap
    • a camera
    • a sweep net
    • a hand lens
    Check