Science 9 · Unit 1: Photosynthesis and the carbon cycle · Cambridge Lower Secondary Science Stage 9

Questions

1. 1. A lizard eats grasshoppers, and grasshoppers eat grass. Why does the lizard depend on photosynthesis for energy?

   • Grasshoppers make energy from oxygen.
   • The lizard gets energy straight from the soil.
   • Lizards can photosynthesise in sunlight.
   • The energy in its food was first captured from sunlight by the grass.
   Check

2. 2. Inside which part of a plant cell is chlorophyll kept?

   • nucleus
   • cell wall
   • chloroplasts
   • vacuole
   Check

3. 3. Why do plants store some of the glucose they make as starch?

   • So they can photosynthesise in the dark.
   • Because glucose is poisonous to plants.
   • So they have food to use later, for example at night.
   • Because starch is a gas that can leave the leaf.
   Check

4. 4. In which layer of a leaf do the cells do most of the photosynthesis?

   • the spongy layer
   • the lower epidermis
   • the waxy layer
   • the palisade layer
   Check

5. 5. How does carbon dioxide get into a leaf?

   • It is made by the palisade cells.
   • It diffuses from the air through tiny holes called stomata.
   • It is taken up from the soil by the roots.
   • It travels up the veins with the water.
   Check

6. 6. Farmers add fertiliser to get a higher yield. What does 'yield' mean?

   • the minerals in the soil
   • the time the crop takes to grow
   • the quantity of crop that is harvested
   • the size of the field
   Check

7. 7. Why do plants need magnesium?

   • to make proteins
   • to take in carbon dioxide
   • to make chlorophyll
   • to make starch
   Check

8. 8. A plant is short of nitrate. Why does it stay small?

   • It cannot store starch.
   • Its leaves cannot get any water.
   • It cannot take in carbon dioxide.
   • It cannot turn carbohydrates into the proteins it needs to make new cells.
   Check

9. 📖 This question is about a text that students read in the app.

   9. How many grains of fertiliser does Sofia put into dish D?

   • 2
   • 0
   • 3
   • 4
   Check

10. 📖 This question is about a text that students read in the app.

    10. Which variable does Sofia change in her experiment?

    • the quantity of fertiliser
    • the light intensity
    • the number of duckweed plants
    • the volume of water
    Check

11. 📖 This question is about a text that students read in the app.

    11. Which of these should Sofia NOT keep the same in her experiment?

    • the temperature
    • the volume of water
    • the number of plants at the start
    • the quantity of fertiliser
    Check

12. 📖 This question is about a text that students read in the app.

    12. Which dish had the most duckweed plants at the end of the experiment?

    • C, with two grains of fertiliser
    • E, with four grains of fertiliser
    • A, with no fertiliser
    • D, with three grains of fertiliser
    Check

13. 📖 This question is about a text that students read in the app.

    13. Sofia concludes: duckweed grows more with extra nitrate fertiliser, but too much stops it growing. Which results support this?

    • Dish A had the most plants.
    • Dishes B, C and D had more plants than A, but dish E, with the most fertiliser, had none.
    • Every dish with fertiliser had more plants than dish A.
    • All the dishes had the same number of plants.
    Check

14. 📖 This question is about a text that students read in the app.

    14. How can Sofia improve her experiment?

    • Put a different number of duckweed plants in each dish.
    • Use a different kind of water plant in each dish.
    • Use three sets of dishes for each quantity of fertiliser.
    • Put each dish in a different temperature.
    Check

15. 15. What is the substance that makes leaves green?

    • chlorophyll
    • iodine
    • glucose
    • starch
    Check

16. 16. Zara's leaf has green parts and white parts. She predicts that the green parts will contain starch, but the white parts will not. Why is her prediction likely to be correct?

    • Starch is green.
    • The white parts get no light.
    • The white parts have no cells.
    • Only the green parts have chlorophyll, so only they can photosynthesise.
    Check

17. 17. In the starch test, why is the leaf put into boiling water first?

    • To add starch to the leaf.
    • To remove the chlorophyll.
    • To make the leaf go green.
    • To break the cell membranes so the iodine can get into the cells.
    Check

18. 18. In the starch test, why is the leaf then put into hot ethanol?

    • To soften the leaf.
    • To remove the green colour, so the colour change is easy to see.
    • To kill the leaf.
    • To make starch.
    Check

19. 19. Why must the burner be turned off before the ethanol is used?

    • Ethanol freezes when heated.
    • Ethanol does not work when it is hot.
    • Ethanol catches fire easily.
    • The leaf would turn blue-black.
    Check

20. 20. What substance causes the iodine to turn blue-black?

    • starch
    • glucose
    • water
    • chlorophyll
    Check