Green Spinach Research

I) Research Question: To what extent does light effect the rate of photosynthesis in green spinach leaves?

II) Hypothesis: If the leaf is exposed to light in the presence of a Carbon source, then the leaf disks float to the surface of the solution due to an increased rate of Oxygen (O2) production through photosynthesis.

III) Hypothesis Explanation: when light is absorbed by leaf pigments such as chlorophyll A or B, electrons within each photosystem are boosted to a higher energy level. Leafs then produce Adenosine Triphosphate (ATP) to reduce NADPH (ferredoxin), and incorporate Carbon dioxide (CO2) into organic molecules in a process called carbon fixation. When leaves are put in the water and undergo the process of the light-dependent reaction,

Using forceps, 5 leaf discs each are put into 10 syringes. They are pushed to the bottom of the syringe with the forceps.

5. 400ml of distilled water along with 8g of sodium bicarbonate are put in a large beaker to prepare a solution. They are stirred to mix them and prepare a solution.

6. The plunger is inserted is interested into the syringe and pushed nearly till the end of the syringe.

7. 6cc of the solution is sucked into the syringe.

8. One finger is place at the tip of the syringe to ensure air doesn’t enter it. The plunger of the syringe is pulled backwards to suck out all the air inside the leaf discs. While the finger is still placed at the tip of the syringe the plunger is now pushed inverts to ensure the solution enters the leaf discs. This is done with all 10 syringes.

9. Almost all of the solution is emptied out into a sink, leaving only about 2cc of the solution.

10. Almost 66cc of tap water is sucked into the syringe.

11. 5 of the syringes are kept close a light source which is 15cm above the syringes and named Set A. The remaining are kept in darkness and labelled Set B. At this point of time all the discs are at the lower end of the syringes.

12. The stopwatch is started as soon as the syringes are

However only one disc rose up in the syringes kept in darkness (Set B). This shows that in the presence of carbon dioxide and light the leaf starts to produce oxygen which is a product of the process of photosynthesis. From the abovementioned readings, it can be seen that almost all of the discs placed in the presence of the light source rose to the top of the syringe as opposed to just one disc out of 25 placed in darkness. Thus, on the basis of the hypothesis it can be said that it is light which facilitates the process of photosynthesis and in the absence of light, photosynthesis cannot occur. This can be said because it is ensured that all other factors except presence/ absence of light were kept constant for both sets of syringes.

IX) Conclusion:

Presence of light is one of the essential ingredients of the process of photosynthesis. In the absence of light, hardly any discs came up to the surface of the water in the syringes. Therefore, light influences photosynthesis to such a great extent, that in the absence of light, when all other factors are kept constant, the process of photosynthesis does not occur, which is demonstrated by negligible number of discs rising in Set B