Science 6 · Unit 4: Food chains and food webs · Cambridge Primary Science Stage 6

Questions

1. 1. What does 'toxic' mean?

   • healthy
   • helpful
   • invisible
   • harmful or poisonous
   Check

2. 2. What does 'accumulate' mean?

   • to break down
   • to build up or increase
   • to move away
   • to disappear
   Check

3. 3. Which is a toxic metal found in food chains?

   • iron
   • calcium
   • mercury
   • oxygen
   Check

4. 4. What are microplastics?

   • big plastic bottles
   • tiny pieces of plastic less than 5 mm across
   • a kind of plankton
   • small fish
   Check

5. 5. How do microplastics form?

   • They grow from seeds.
   • Rain makes them.
   • Fish make them.
   • Larger plastics are broken down by sunlight and waves.
   Check

6. 6. Why do farmers use pesticides?

   • to feed the crops
   • to water the crops
   • to attract birds
   • to get rid of pests that eat their crops
   Check

7. 7. How can a pesticide harm a butterfly that is not a pest?

   • It can't be harmed.
   • It eats the farmer.
   • It gets too much sun.
   • It drinks nectar from a sprayed flower.
   Check

8. 8. How does a pesticide move through a food chain?

   • It blows in the wind only.
   • Only plants are affected.
   • Each animal takes in the pesticide from what it eats.
   • It disappears at each link.
   Check

9. 9. Why do top predators get the most of a toxic substance?

   • They eat only plants.
   • They eat many animals that each contain some.
   • Toxins break down before they reach them.
   • They are the smallest.
   Check

10. 10. A bug has 5 units of pesticide. A lizard eats 3 bugs. How many units does the lizard have?

    • 3
    • 5
    • 8
    • 15
    Check

11. 11. The lizard has 15 units. An eagle eats 2 lizards. How many units does the eagle have?

    • 15
    • 17
    • 30
    • 2
    Check

12. 12. How did DDT harm birds of prey like eagles?

    • Their eggs had very thin shells that cracked.
    • It made their eggs bigger.
    • It made them fly faster.
    • It gave them more food.
    Check

13. 13. Why was DDT used a lot in the past?

    • to make plants grow
    • to kill mosquitoes that spread malaria and to spray crops
    • to clean water
    • to feed birds
    Check

14. 14. Why can DDT move through food chains?

    • It breaks down quickly.
    • It turns into water.
    • Animals' bodies cannot get rid of it; it is stored in fat.
    • It only stays in plants.
    Check

15. 15. Chemical X: pond weed 4 units, tadpole 20, fish 240, heron 500. Which has the most?

    • the fish
    • the pond weed
    • the tadpole
    • the heron
    Check

16. 16. How do plastics harm sea animals?

    • Plastic cleans the water.
    • Plastic feeds them.
    • Plastic keeps them warm.
    • Animals swallow plastic, which can block their digestive systems.
    Check

17. 17. How do ecobricks help reduce plastic waste?

    • They throw plastic in the sea.
    • Plastic waste is packed into bottles used to build schools.
    • They make more plastic.
    • They burn plastic.
    Check

18. 18. Can toxic substances in food chains affect humans?

    • Only if we touch them.
    • No, never.
    • Only plants are affected.
    • Yes, if we eat plants or animals that contain them.
    Check