Required Practical - Photosynthesis

Question 1

What equipment do you need for this practical?

Answer 1

pondweed
scissors
boiling tube of water
test tube rack
large beaker of water
lamp
metre rule
stopwatch
thermometer

Question 2

What is the method for this practical?

Answer 2

1. Cut a piece of pondweed 8–10 cm long (pre cut). Place it in a boiling tube of water/bicarbonate with the cut end upwards.
2. Use the thermometer to measure the temperature of the water in the boiling tube.
3. Place the boiling tube in a large beaker of water to act as a heat shield and position it 10cm away from the lamp.
4. Wait until there is a steady flow of bubbles from the cut end of the pondweed. Count the number of bubbles in 2 minutes. Record this in the first blank column of the results table.
5. Measure the temperature of the water in the boiling tube again to make sure it has not changed.
6. Repeat steps 1–5 four more times but in step 3 increase the distance between the lamp and boiling tube by 10 cm each time.
7. Repeat the whole investigation (steps 1–6) two more times and record the results in the second and third blank columns of the table.
8. Calculate the mean number of bubbles for each distance, leaving out any anomalous values from your calculations. Record it in the fourth blank column, giving your answer to the nearest whole number.