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Describe the practical for investigating the rate of photosynthesis
Set up a boiling tube containing 45 cm3 of sodium hydrogencarbonate solution (1%). Allow the tube to stand for a few minutes and shake to disperse any air bubbles that might form.
Cut a piece of the pondweed, Cabomba. The pondweed should be 8 cm long.
Use forcepts to place the pondweed in the boiling tube carefully. Make sure that you don't damage the pondweed, or cause the liquid to overflow.
Position the boiling tube so that the pondweed is 10 cm away from the light source. Allow the boiling tube to stand for five minutes. Count the number of bubbles emerging from the cut end of the stems in one minute. Repeat the count five times and record your results.
Calculate the average number of bubbles produced per minute. Repeat the experiment at different distances away from the light source.
What are the variables for this experiment
Light intensity- independent variable
Dependent variable – the number of bubbles produced per minute.
Control variables – concentration of sodium hydrogencarbonate solution, temperature, using the same piece of Cabomba pondweed each time.
Write out equation for inverse square law
Light intensity (proportional symbol ) 1/distance(d)2

How do farmers artificially create conditions required for photosynthesis
-in colder climates- Phone was often place crops in greenhouses which trap in heat (so it increases the temperature)
– They can also provide artificial light so photosynthesis can continue to occur all through the day and night
-Sometimes farmers may pump carbon dioxide into greenhouses or use paraffin heater which releases both heat and carbon dioxide as it burns
– Farmers may also use fertilisers to ensure plants have enough essential minerals and pesticides to kill any unwanted bugs
What is one problem that farmers may face bc of artificially controlling plant growth
Cost , controlluhg conditions in greenhouses are expensive