Photosynthesis

Question 1

2 problems

What are the problems with this experiment and how can they be negated?

Answer 1

1. Number of bubbles may be too fast to count accurately.
2. Bubbles are not all the same size.
   Fix: Place pondweed under funnel and catch bubbles in measuring cylinder.
   Use measuring cylinder to measure volume of oxygen produced.

Question 2

7 steps

What are the steps for recording photosynthesis rate?

Include terms: Boiling Tube, LED, Sodium Hydrogen Carbonate, Pondweed, Acclimatise, Stopwatch, Repeat, Mean,

Answer 2

1. Take** boiling tube and place 10cm away from LED light source** ( does not release much heat which would change temperature of experiment).
2. Fill tube with sodium hydrogen carbonate solution (releases CO2 needed for photosynthesis)
3. Put piece of pondweed into boiling tube with cut end at the top.
4. Leave for 5 minutes to acclimatise to boling tubes conditions.
5. Start stopwatch and count number of bubbles per minute.
6. Repeat step 5 two more times to calculate mean number of bubbles per minute.
7. Repeat experiment at 20cm, 30cm and 40cm away from LED light source.