investigating the rate of photosynthesis

experiment for investigating the rate of photosynthesis

the rate at which the pondweed produces oxygen corresponds to the rate that it is photosynthesising

set up pondweed experiment

place white light source at specific distance
leave the pondweed for a couple minutes to adjust to the new light intensity
leave to photosynthisise for set amount of time
oxygen will collect in capillary tube
use syringe to draw gas bubble from tube alongside ruler
measure length of gas bubble
repeat twice at same distance and calculate mean volume of o2 collected
repeat at different distances

control variables of pondweed experiment

time
same plant
amount of light

dependent variable in pondweed experiment

amount of o2 produced

independent variable of pondweed experiment

light intensity

calculating the rate of photosynthesis

total length of bubble / time taken to produce it

light intensity is directly proportional to

1/distance^2

the inverse square law means

half distance, light intensity 4 times largerthird distance, light intensity 9 times largerdouble distance, light intensity 4 times smallertreble distance, light intensity 9 times smaller