2. Describe and Explain
If a question asks you to describe what is happening in a graph then tell me what is happening – don’t try and tell me why.
If you can include figures.

3. Describe and Explain
Rate of photosynthesis/arbitrary units
Describe the effect of CO2 conc. on the rate of photosynthesis. (2)
Rate of photosynthesis increases from 0 to 0.1% carbon dioxide.
After 0.1% there is no further increase in the rate of photosynthesis.

4. Describe and Explain
If a question asks you to explain what is happening in a graph then tell me why it is happening – don’t tell me what has happened.
Think about how you would answer reaction questions in chemistry – collisions – and biology terms – other limiting factors, denaturing.

5. Describe and Explain
Rate of photosynthesis/arbitrary units
Explain the effect of CO2 conc. on the rate of photosynthesis. (3)
Rate of photosynthesis increases from 0 to 0.1% carbon dioxide because carbon dioxide is one of the reactants for photosynthesis.
After 0.1% there is no further increase in the rate of photosynthesis because other limiting factors are involved e.g. light, temperature.

6. Describe and Explain
Describe the effect of increasing walking speed on oxygen use. (3)
Between 0 and 3 km/hr oxygen use increases slowly with an increase in walking speed.
Between 3 and 4 km/hr the rate of oxygen used increases more.
From 4 km/hr onwards there is a rapid increase in the amount of oxygen used as speed increases.

7. Describe and Explain
Explain the effect of increasing walking speed on oxygen use. (2)
When walking at faster speeds a person needs to respire more so that they can provide energy for their muscles to contract.
This means that they need to use more oxygen so that they can respire aerobically.

8. Describe and Explain
Describe the effect of temperature on the rate of reaction. (3)
The rate of reaction increases as temperature increases, up to 40⁰C, which is the optimum temperature.
Beyond 40 ⁰C the rate of reaction decreases as temperature increases.

9. Describe and Explain
Explain the effect of temperature on the rate of reaction. (4)
Up to 40 ⁰C the rate of reaction increases as higher temperatures give the enzyme and substrate more energy so there are more successful collisions. 40 ⁰C is the optimum temperature.
Beyond 40 ⁰C the rate of reaction decreases as enzymes are denatured by high temperatures.

10. Describe and Explain
Describe the effect of temperature on the time taken to digest the egg white. (3)
The time taken to digest the egg white decreases as temperature increases, up to 40⁰C, which is the optimum temperature.
Beyond 40 ⁰C the time taken to digest the egg white decreases as temperature increases.

11. Describe and Explain
Explain the effect of temperature on the time taken to digest the egg white. (4)
Up to 40 ⁰C the time taken to digest the egg white decreases as higher temperatures give the enzyme and substrate more energy so there are more successful collisions. 40 ⁰C is the optimum temperature.
Beyond 40 ⁰C the time taken to digest the egg white increases as enzymes are denatured by high temperatures.