Biology TAS

I can only suggest you with some points ...

Principle of design:
The experimental set-up is designed to collect and mesaure the volume of oxygen given out within a given perios of tim when a table lamp is placed in front of the Hydrilla at a certain distance. A beaker of water which hold the Hydrilla inside a test tube acts as a heat shield.

Sources of error: (for this part i copy from TAS answer)
1. the method of estimating the rate is inaccurate, as bubbles size may not be uniform and the bubbles are difficult to count. It would be better to collect the oxygen and express the rate as volume of O2 evoloved per min.

2. theinstructions do not suggest on acclimatisation period before making observations thus the plants may be photosynthesising at varying rates during the observation. Five or ten min should be allowed to elapse after moving the lamp.

3. Only one obeservation at wach distance is sugested but more accurate results would be obtained by making several counts and then taking an average.

I hv the procedures too. Tell me if you want, i will type it for you.
Hope these help you.