Comparing the rate of photosynthesis with
different wavelengths of light
By Juvelle Taylor
Article submitted on October 17, 2008. Published by biologyonline.com.
Planning and Designing
CO2 can be bubbled into bromothymol blue to give
a yellow colour. If an Elodea plant is placed in the solution, the time taken
for the solution to change back to blue will be equal to the rate at which the
plant uses CO2 in photosynthesis. Plan and design an experiment to
compare the rate of photosynthesis with the different wavelengths of light.
Hypothesis: With a blue filter the photosynthetic rate
will be the highest, as blue is a highly absorbent color; it also has a short
wavelength so carries the most energy. The color to have the least
photosynthetic rate will be green as although it has quite a short wavelength a
lot of energy will be reflected by the plant and not absorbed.
Independent Variable: light
Dependent Variable: the
no. of oxygen bubbles given off per minute
Aim: To compare the rate of photosynthesis with
different wavelengths of light.