Exam practice
Exam questions
Write your answer. Then open the mark scheme and tick each point you made.
- Question 1 of 102 marks
Write the word equation for photosynthesis.
Mark scheme
- Carbon dioxide + water, before the arrow (in either order)
- Glucose + oxygen, after the arrow (in either order)
- Question 2 of 102 marks
State where the energy for photosynthesis comes from, and name the substance in a leaf that absorbs it.
Mark scheme
- Light (accept: sunlight, the Sun)
- Chlorophyll
- Question 3 of 102 marks
Give two ways in which a plant uses the glucose it makes.
Mark scheme
- As a source of energy (accept: for respiration)
- To build new tissue (accept: to grow)
- To store for later (accept: it is stored as starch)
- Question 4 of 103 marks
A plant has variegated leaves: each leaf is green in the middle and white round the edge. The plant is kept in the dark for two days, to use up the starch in its leaves. Next it is left in bright light for a day. Then one leaf is tested for starch with iodine solution. Describe the result and explain it.
Mark scheme
- The green part goes blue-black
- The white part stays orange-brown (accept: brown, yellow-brown)
- Only the green part has chlorophyll, so only the green part photosynthesised and made starch
- Question 5 of 102 marks
In a dark room, a student moves a lamp further away from some pondweed and counts the bubbles it gives off each minute. Nothing else changes. Describe what happens to the number of bubbles, and explain why.
Mark scheme
- The number of bubbles goes down
- Less light reaches the pondweed, so it photosynthesises more slowly (accept: it makes less oxygen)
- Question 6 of 102 marks
Most leaves are broad and thin. Explain how each of these two features helps a leaf to photosynthesise.
Mark scheme
- Broad: a large surface area absorbs more light
- Thin: carbon dioxide has only a short distance to go to reach the cells (accept: gases can get in and out quickly)
- Question 7 of 102 marks
Describe the job of the stomata and the job of the guard cells.
Mark scheme
- Stomata let carbon dioxide into the leaf and oxygen out (accept: let gases in and out)
- Guard cells open and close the stomata
- Question 8 of 102 marks
Explain how a root hair cell is adapted to take in water.
Mark scheme
- It has a long, thin part (accept: a hair) that gives it a large surface area
- So it can take in more water (accept: take in water more quickly)
- Question 9 of 102 marks
Name the mineral that a plant needs to make chlorophyll, and describe how a plant looks when it does not get enough of it.
Mark scheme
- Magnesium
- Its leaves are yellow (accept: pale)
- Question 10 of 102 marks
Give two reasons why animals depend on photosynthesis.
Mark scheme
- Plants and algae are producers: they make the food at the start of food chains (accept: animals eat plants, or eat animals that ate plants)
- Photosynthesis gives out the oxygen that animals need for respiration (accept: to breathe)