To investigate the influence of light intensity or carbon dioxide on the rate of photosynthesis

Question 1

Step 1

Answer 1

Add excess sodium bicarbonate to some water in a test tube
(Water is saturated with CO2 which ensures constant concentration of CO2)

Question 2

Step 2

Answer 2

Cut a section of elodea and place it in the test tube. (lamp placed 1 metre from apparatus)

Question 3

Step 3

Answer 3

Leave for 5 mins to allow elodea to adjust to the conditions

Question 4

Step 4

Answer 4

Count number of bubbles coming from the cut end of the stem per min. (3x)

Question 5

Step 5

Answer 5

Add the 3 no. and divide by 3 to calculate average

Question 6

Step 6

Answer 6

Increase the light intensity by moving the lamp closer

Question 7

Step 7

Answer 7

Repeat steps 3 & 5 every time the lamp is moved

Question 8

Step 8

Answer 8

Record results in a table

Question 9

Conclusion

Answer 9

As the lamp moves closer to the apparatus, the rate of bubbles increases. When it stops increasing, it’s because it is the said to be saturated with light