The spinach leaf
Aim: The aim of this experiment is to investigate the effect of sodium carbonate and light intensity on the rate of oxygen produced by plants by observing the floating of the Spinach leaf. Hypothesis: When the light hit the leaf it is absorbed by it in order to be used in the process of photosynthesis, which is the process of producing oxygen, but at the same time, light reaches plants in different rates, which may play a role in the production of oxygen.
In the presence of a carbon source, if a leaf is to a higher intensity of light, then it will take a less time for the spinach disks to float, due to the increase of oxygen gas which pushes it up.
Variables: Controlled: 1) The temperature was constant for almost all the time 2) Volume of liquid in syringe 3) Spinach leaves 4) Number of disks made by hole puncher Independent: 1) Intensity of light that was used in the experiment Dependent: 1) the time it took each of the disks to float, since each of the disks had different time and the light it was getting Tools and materials: 1) plastic cups 2) stirring rod 3) stand 4) beakers 5) stopwatch 6) spinach leaves 7) microscopic light 8) ruler 9) hole puncher 10) liquid soap 11) syringe.
Procedure: 1) Label the 4 plastic cups with: – 20 cm CO2 light – 10 cm CO2 light – 10 cm Water/ soap light – CO2 dark 2) number the beakers 1 and 2 3) add 6. 3g of baking soda and mix it with 300ml of water using stirring rod 4) mix some soap with 200ml of water using stirring rod 5) add one drop of dilute soap in the beaker number 1.
6) Make 10 disks of the spinach leaf using the hole puncher 7) Remove the moving part of the syringe and add the disks in to it 8) Then put back the part of the syringe back in and slowly push it down to remove as much oxygen as possible
9) Dip the opening of the syringe in the beaker labeled with number 1, which is the bicarbonate solution, and pull it back filling it with 3 cc 10) Placing your finger on the opening push the syringe down as much as you can to create a vacuum and force as much air out. And then pull it back up to create a vacuum and hold it for 10 seconds. 11) Repeat it as much as you need until the leaf sinks 12) Then pour the disks and the solution in the right cup and add bicarbonate solution until the cup is 34 full 13) Then after that place the cups with the leafs above the 15w microscopic light.
14) Do the same for trial 2 and 3 but replace the cups 10 cm from the light stand 15) As soon as the leafs are exposed to light start timing 16) Record the time of number of disks floating everyminute 17) Keep doing this until all disks have floated or you’ve reached 30 min 18) Do the same for the dark but what changes is that you put it at first 10 cm above light for 14 min and count number of disks floating every minute and then turn of the light for 14 min abd put it in the dark during these 14 minutes. Also to make this experiment more accurate it can be done multiple times and better results will be obtained.
