Pupil sheet · How plants make food
How plants make food — final check
Name ______________________ Date ____________
Work alone, with the lesson closed. Answer every question; there are no hints.
1. describe / state
Describe what photosynthesis is, and state its word equation.
(a) What photosynthesis is
(b) Word equation
2. state / explain
A student says: "Chlorophyll is the food that a plant makes." (a) State what chlorophyll is and where it is found. (b) Explain what chlorophyll does in photosynthesis.
(a) What and where
(b) What it does
3. explain
Supplement. (a) State the balanced chemical equation for photosynthesis. (b) In your equation, what does the 6 in front of CO₂ tell you, and what does the small 2 in CO₂ tell you? (c) Show that the hydrogen atoms balance.
(a) Balanced equation
(b) The 6 and the 2
(c) Hydrogen count
4. describe / explain
Describe how to test a leaf for starch. Give a reason for each step.
5. describe
Describe how you would show that a leaf needs carbon dioxide to make starch. Include the control and the results you would expect.
6. predict / explain
A destarched variegated leaf (green middle, cream edges) has a strip of foil folded over both surfaces across its middle, so that both green and cream parts are covered. After a day under a lamp it is tested for starch. The table names four parts of the leaf. (a) Which part or parts turn blue-black? (b) Explain why each other part stays orange-brown.
| Part of the leaf | Colour before | Covered by foil? |
|---|---|---|
| W | green | no |
| X | green | yes |
| Y | cream | no |
| Z | cream | yes |
(a) Blue-black parts
(b) Why the others stay orange-brown
7. outline
Outline how a plant uses and stores the glucose it makes in photosynthesis. Give five uses.
8. identify / explain
Plant A is small and weak, and its older leaves are yellow. Plant B is a fair size, but its older leaves are yellow between the veins. Each is short of one of these: nitrate ions or magnesium ions. (a) Which ion is each plant most likely short of? (b) Explain why each ion matters to a plant.
(a) Plant A and plant B
(b) Why each ion matters
9. evaluate / suggest
To find out whether wheat needs magnesium, a student grows one seedling in a complete solution on a sunny windowsill, and one seedling in a solution without magnesium in a dim corner of the room. After three weeks, the second seedling is shorter and paler. He concludes that wheat needs magnesium. (a) Give two reasons why his conclusion is not reliable. (b) Suggest how to improve the investigation.
(a) Why not reliable
(b) Improvements