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

Questions

1. 1. What are microplastics?

   • a type of algae
   • tiny sea creatures
   • tiny pieces of plastic less than 5 mm long
   • plastic bottles
   Check

2. 2. Where do microplastics come from?

   • large plastics breaking apart, and some health and beauty products
   • rainwater only
   • volcanoes
   • fish scales
   Check

3. 3. Why are some microplastics found in mud on the sea bed?

   • They are made there.
   • Denser microplastics slowly sink.
   • They float up from the mud.
   • Fish bury them.
   Check

4. 4. Why might filter-feeding fish contain microplastics?

   • They make microplastics.
   • They take in microplastics with the zooplankton they filter.
   • They eat plastic bottles.
   • Microplastics are a fish food.
   Check

5. 5. What is bioaccumulation?

   • the build-up of a substance in an organism's body over time
   • the breakdown of food
   • the spread of seeds
   • the growth of a population
   Check

6. 6. Why may seals have more microplastics than the fish they eat?

   • Seals make plastic.
   • Seals live longer in water.
   • Each seal eats many fish, collecting their microplastics.
   • Fish have no microplastics.
   Check

7. 7. Why can't living things get rid of microplastics?

   • They cannot be broken down by living things.
   • They turn into food.
   • They dissolve too quickly.
   • They are too large to swallow.
   Check

8. 8. Which animals are most at risk from a toxic chemical spray?

   • the decomposers only
   • the first consumers only
   • the producers
   • those higher up the food chain
   Check

9. 9. Why might a chemical company's information about its spray be biased?

   • It has no interest in sales.
   • The company profits from selling the spray.
   • It is a university study.
   • It is a government department.
   Check

10. 10. Could a company selling predator insects also give biased information?

    • Only if it's a chemical company.
    • No, because it is environmentally friendly.
    • No, never.
    • Yes, it also profits from selling its product.
    Check

11. 11. What problem could predator insects cause if they eat other insects?

    • They would only help crops.
    • There would be no problem.
    • They would make maize grow.
    • They could reduce insects that are essential for the ecosystem.
    Check

12. 12. How could the farmers check information for bias?

    • ignore all information
    • trust the first advert
    • compare several independent sources, such as scientists not selling products
    • ask only the seller
    Check

13. 13. Microplastics in sea-bed mud rose from about 40 per kg in 1996 to about 140 in 2008. What was the increase?

    • about 180 per kg
    • about 3.5 per kg
    • about 100 per kg
    • about 40 per kg
    Check

14. 14. What does 'environmentally friendly' usually claim?

    • that something does little harm to the environment
    • that it kills all insects
    • that it is made of plastic
    • that it is cheap
    Check

15. 15. The department suggests growing crops the pests won't eat. Why would this work?

    • The crops poison the pests.
    • It attracts more pests.
    • Without food the pests will move away or die.
    • The pests prefer them.
    Check

16. 16. Why is DDT called a persistent chemical?

    • It doesn't break down, so it stays in the environment for years.
    • It kills insects very quickly.
    • It dissolves easily in water.
    • It is only used once.
    Check

17. 17. DDT in a food chain: minnows 0.50 ppm, cormorants 26.40 ppm. How many times greater is the concentration in a cormorant?

    • 0.019 times
    • 52.8 times
    • 13.2 times
    • 25.9 times
    Check

18. 18. What is biomagnification?

    • a microscope making things look bigger
    • the concentration of a substance increasing along a food chain
    • an animal growing larger as it ages
    • a substance breaking down in the soil
    Check

19. 19. Who wrote the book Silent Spring in 1962, showing that DDT was killing birds?

    • Rachel Carson
    • Isaac Newton
    • Ernest Rutherford
    • Mary Anning
    Check

20. 20. Winged loosestrife alone had 35 insect visits and 80 seeds per plant; next to purple loosestrife it had 26 visits and 58 seeds. Do the results support the idea that purple loosestrife reduces its pollination?

    • Yes
    • No
    Check