1. Photosynthesis in one sentence (5 marks)
Photosynthesis is a chemical reaction
that takes place in the chloroplasts
in green plant cells, where light energy
is used to convert carbon dioxide and water into glucose and oxygen.
In your books.
Then in another colour annotate any additions.

2. Specification Link
Demonstrate an understanding of how limiting factors affect the rate of photosynthesis, including:
a) light intensity
b) CO2 concentration
c) temperature
Investigate how factors, including the effect of light intensity, CO2

3. Biggest Greenhouse in the UK

4. Why would farmers spend so much money building this greenhouse?

5. What are the limiting factors of photosynthesis?
Rate of photosynthesis depends on the growing conditions.
Things that slow photosynthesis down are called limiting factors.
What are the limiting factors of
photosynthesis?
Farmers want to get the biggest crops possible
from their fields and greenhouses. To do this they
need to provide the best possible conditions for
photosynthesis and growth.

6. What is a limiting factor?
What is the ideal combination of factors for the maximum rate of photosynthesis?
enough light
enough carbon dioxide
ideal temperature (not too hot or cold)
What will happen to the rate of photosynthesis if one of these factors is restricted?
The rate of photosynthesis will be below the maximum possible rate.
The restricted factor controls how quickly photosynthesis occurs and so limits the rate. It is called the limiting factor.

7. Photosynthesis and light – limiting factors
How does the amount of light affect the rate of photosynthesis on this labelled graph? 1
As the amount of light increases, so does the rate. The limiting factor is light. 2
rate of photosynthesis 2
Here, increasing the amount of light has no affect on the rate. The limiting factor is now carbon dioxide or temperature.
What must be increased for the rate to increase? 1
light intensity

8. Photosynthesis and carbon dioxide – limiting factors
How does the amount of carbon dioxide affect the rate of photosynthesis on this labelled graph?
As the amount of carbon dioxide goes up, so does the rate. The limiting factor is carbon dioxide. 1 2
rate of photosynthesis
Here, increasing the amount of carbon dioxide has no affect on the rate. Light or warmth is now the limiting factor.
What must be increased for the rate to increase? 2 1
concentration of
carbon dioxide

9. Photosynthesis and temperature – limiting factors
How does temperature affect the rate of photosynthesis on this labelled graph? 1
As temperature increases, so does the rate because photosynthetic enzymes work best in the warmth. Here, the limiting factor is temperature.
rate of photosynthesis 2 1
Most plant enzymes are destroyed at about 45°C. Here, photosynthesis stops and the rate falls to zero.
What is the limiting factor? 2
0oC
temperature
45oC

11. Photosynthesis Investigation
In this investigation, you are going to study the photosynthesis of pondweed (Elodea).
Using the apparatus shown in the diagram, the photosynthesis can be measured by the number of bubbles of oxygen produced by pondweed in a certain amount of time.
clamp
pondweed
sodium hydrogencarbonate solution
bubbles of oxygen
test tube
beaker

12. Investigating limiting Factors
Aim- To see how light intensity can affect the rate of photosynthesis.
Distance of Lamp
Amount of Bubbles in 1 Minute
Extension- Write a conclusion for your experiment, if your experiment did not work very well then explain why you think this is and suggest possible improvements.