gce winter 2010 - question paper - KCSE Online

6
Examiner
only
(b)
The following apparatus was assembled, using different coloured filters, to investigate
the effect of light wavelength on the rate of photosynthesis. The dissolved oxygen
electrode measures the concentration of oxygen in the solution around the Canadian
pondweed. The experiment was repeated a number of times.
black box
light
source
computer
interface
(i)
coloured
filter
Canadian
pondweed
dissolved
oxygen
electrode
Explain how the use of dissolved oxygen electrode allowed the rate of
photosynthesis to be determined. [2]
.........................................................................................................................................................................................................
.........................................................................................................................................................................................................
(ii)
Give two sources of inaccuracy with this experimental set up and explain how it
could be corrected. [2]
1. Inaccuracy ......................................................................................................................................................
Correction ......................................................................................................................................................
2. Inaccuracy ......................................................................................................................................................
Correction ......................................................................................................................................................
(314-01)