Justins Lab Report
Introduction
The aim of this practical 1 is to determine the rate of photosynthesis by measuring the rate of oxygen production, which is a direct consequence of PSII activity.
Results
Graph 1
Graph 2
Discussion
i. It took 2 minutes before any increase in the O2 concentration of the chamber was observed, it took 2minutes, after illuminating the leaf. ii. There are 2 main parts of the photosynthesis, light dependent part and light independent part, the O2 is released in last part which is light-independent part. Also it takes time to let the produces from the fore part, light dependent part to the light independent part. Therefore, the O2 evolution didn’t begin at the moment that light was supplied. iii. After O2 evolution from the leaf began to increase, it didn’t increase continue in a linear manner because after reaching saturation point, CO2 became a limiting factor of the experiment.
Calculations
Area of the leaf = 21.875cm2 = 0.0021875m2
Condition
Slope (%O2/min)
Photosynthetic Rate (μmol O2/m2/min)
(correct to 3 decimal places)
Phase 1
0.032
281.026
Phase 2
0.045
395.193
Phase 3
0.035
307.372
Phase 4 (Dark)
0.026
228.333
Table 1
Conclusion
In this experiment, we found that the highest rate of photosynthesis is phase 2 and the O2 concentration in the chamber didn’t reach steady state in the light but decline gradually when the light was turned off.
Questions to answer
(i) The highest photosynthetic rate is in Phase 2.
(ii) Estimate the CO2 concentration in the chamber at the point of maximum photosynthetic rate (Phase 2):
100%-78% (N2 concentration) - 6.5% (O2 concentration)
=15.5%(CO2 concentration)
(iii) Photosynthetic rate decline towards the end of the experiment in the light because the CO2 is the limited factor in chamber. The photosynthetic rate is higher than the rate of respiration so the CO2 concentration decline.
(iv) The O2 concentration in the chamber didn’t reach steady state in the light because the photosynthetic rate
The aim of this practical 1 is to determine the rate of photosynthesis by measuring the rate of oxygen production, which is a direct consequence of PSII activity.
Results
Graph 1
Graph 2
Discussion
i. It took 2 minutes before any increase in the O2 concentration of the chamber was observed, it took 2minutes, after illuminating the leaf. ii. There are 2 main parts of the photosynthesis, light dependent part and light independent part, the O2 is released in last part which is light-independent part. Also it takes time to let the produces from the fore part, light dependent part to the light independent part. Therefore, the O2 evolution didn’t begin at the moment that light was supplied. iii. After O2 evolution from the leaf began to increase, it didn’t increase continue in a linear manner because after reaching saturation point, CO2 became a limiting factor of the experiment.
Calculations
Area of the leaf = 21.875cm2 = 0.0021875m2
Condition
Slope (%O2/min)
Photosynthetic Rate (μmol O2/m2/min)
(correct to 3 decimal places)
Phase 1
0.032
281.026
Phase 2
0.045
395.193
Phase 3
0.035
307.372
Phase 4 (Dark)
0.026
228.333
Table 1
Conclusion
In this experiment, we found that the highest rate of photosynthesis is phase 2 and the O2 concentration in the chamber didn’t reach steady state in the light but decline gradually when the light was turned off.
Questions to answer
(i) The highest photosynthetic rate is in Phase 2.
(ii) Estimate the CO2 concentration in the chamber at the point of maximum photosynthetic rate (Phase 2):
100%-78% (N2 concentration) - 6.5% (O2 concentration)
=15.5%(CO2 concentration)
(iii) Photosynthetic rate decline towards the end of the experiment in the light because the CO2 is the limited factor in chamber. The photosynthetic rate is higher than the rate of respiration so the CO2 concentration decline.
(iv) The O2 concentration in the chamber didn’t reach steady state in the light because the photosynthetic rate