1. Photosynthesis - Limiting Factors
WALT :
Explain that Photosynthesis rate is affected by environmental factors
Explain How to measure the rate of photosynthesis
WILF – Graph of Results
Questions answered

2. Limiting Factors Light Intensity Carbon dioxide Temperature
Resources that affect the maximum rate of photosynthesis
For your test you need to know 3:
Light Intensity
Carbon dioxide
Temperature

3. Light Levels What happens to the rate of photosynthesis when you
increase the light level at low temperatures
increase the light level at high temperatures

4. 1a) As you increase light intensity, the rate of Photosynthesis increases but levels off quickly at low temperatures 1b) At high temperatures the rate of photosynthesis continues to rise

5. 1b) When you increase the light levels at low temperature the rate of photosynthesis increases exponentially until another limiting factor takes over

6. Carbon dioxide levels
2) What happens to the rate of photosynthesis when you increase the CO2 level?

7. Temperature At low temperatures photosynthesis enzymes stop working
At high temperatures the photosynthesis enzymes are denatured (broken up)
3) What happens to the rate of photosynthesis when you increase the temperature that the plant is in?

8. 3) As you increase the temperature, the rate of photosynthesis increases up to a point. Beyond this temperature the enzymes denature and photosynthesis quickly stops

9. Practical – Measuring Rate of Photosynthesis
                                 

10. Graph the following results
Graph the following results. You may use the same paper, but be aware of the axes
Remember : What you change goes on the x axis, what you measure on the y axis

11. Increasing Light Intensity
Number of bubbles produced
1.0 4
2.6 8
4.2 11
5.2 14
6.5 13
7.3
8.6 16
10.0 17

12. Increasing CO2 Concentration
Concentration of CO2
Number of bubbles produced
2.0 16
2.3 18
2.9 20
3.8 26
4.5 27
5.2
6.0
6.7

13. What can we say about these results?
Discuss with your neighbour
Think of an ‘er, er’ rule we can make

14. The greater the light intensity the more bubbles are produced
What happens to the number of bubbles produced when CO2 levels are increased?

15. The number of bubbles produced levels off This is because a limited amout of something else occurs (eg light or temperature)