Gr 12 factors of photosynthesis

Photosynthesis is dependent on a number of favourable conditions, including:

Photosynthesis is controlled by enzymes, which are sensitive to temperature fluctuations
As temperature increases reaction rate will increase, as reactants have greater kinetic energy and more collisions result
Above a certain temperature the rate of photosynthesis will decrease as essential enzymes begin to denature

Light is absorbed by chlorophyll, which convert the radiant energy into chemical energy (ATP)
As light intensity increases reaction rate will increase, as more chlorophyll are being photo-activated
At a certain light intensity photosynthetic rate will plateau, as all available chlorophyll are saturated with light
Different wavelengths of light will have different effects on the rate of photosynthesis (e.g. green light is reflected)

arbon dioxide is involved in the fixation of carbon atoms to form organic molecules
As carbon dioxide concentration increases reaction rate will increase, as more organic molecules are being produced
At a certain concentration of CO₂ photosynthetic rate will plateau, as the enzymes responsible for carbon fixation are saturated

Measuring CO₂ Uptake

Carbon dioxide uptake can be measured by placing leaf tissue in an enclosed space with water
Water free of dissolved carbon dioxide can initially be produced by boiling and cooling water
Carbon dioxide interacts with the water molecules, producing bicarbonate and hydrogen ions, which changes the pH (↑ acidity)
Increased uptake of CO₂ by the plant will lower the concentration in solution and increase the alkalinity (measure with probe)
Alternatively, carbon dioxide levels may be monitored via a data logger

Measuring O₂ Production

Oxygen production can be measured by submerging a plant in an enclosed water-filled space attached to a sealed gas syringe
Any oxygen gas produced will bubble out of solution and can be measured by a change in meniscus level on the syringe
Alternatively, oxygen production could be measured by the time taken for submerged leaf discs to surface
Oxygen levels can also be measured with a data logger if the appropriate probe is available

Measuring Biomass (Indirect)

Glucose production can be indirectly measured by a change in the plant’s biomass (weight)
This requires the plant tissue to be completely dehydrated prior to weighing to ensure the change in biomass represents organic matter and not water content
An alternative method for measuring glucose production is to determine the change in starch levels (glucose is stored as starch)
Starch can be identified via iodine staining (turns starch solution purple) and quantitated using a colorimeter

Virtual Lab about Light Intensity

By following Instructions on this Virtual Lab Experiment, you will produce a graph of your results.

Collect and organize your data.

Analyze your data: Determine the average amount of gas produced

Find the optimal factors that cause the plant to grow the most

Respond in Writing:

Describe the experiments you performed.
What did you find out? Which factors had a positive effect on the plant, which ones had a negative effect on the plant? Use data from the virtual labs to support your answer.

You will create a table with your results and then a graph of these results

Your graph will have 3 lines

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