How Light Affects The Rate Of Photosynthesis

We can see through the results that there isn’t a normal proportional relationship between the wavelength of the light and the rate of photosynthesis and instead it starts relatively high then decreases and increases again. The colour red gives the highest rate of photosynthesis (89 bubbles per minute) with blue giving the second highest rate of photosynthesis (70 bubbles per minute), and yellow giving the third highest rate of photosynthesis (64 bubbles per minute) and green with by far the least (44 bubbles per minute). Although, we can see no direct correlation between the rate of photosynthesis and the wavelength of the light used, we can see a relationship between the colour of the leaf, the rate of photosynthesis and the colour of light used. With colours that are similar to the colour of the leaf such as green and yellow, lower rates of photosynthesis were identified while colours that were opposite to the colour of the leaf gave the highest rate of photosynthesis such as red. All of the results compared to the control showed a lower rate of photosynthesis as white light is made up of a mixture of all wavelengths of light, including wavelengths that cause a very high rate of photosynthesis.
This relationship can be explained by the fact that wavelengths of light that are a similar colour to the plant leaf would be reflected off as it cannot be absorbed and thus allow the leaf to be that colour, while the wavelengths of light that are different from the colour of the leaf would be absorbed.
As the process of photosynthesis requires light in the beginning of the process, also known as the light dependent reactions, we can assume that more light absorbed would cause a greater rate of photosynthesis as long as all other limiting factors are in excess such as carbon dioxide concentration, concentration of chlorophyll and
water.
In the light dependent reaction light it used to split water so that hydrogen ions are released and oxygen is produced. The light absorbed by the chlorophyll allows the electrons to be excited in photosystem II and passed along the electron carriers where the energy of the electrons are used in the pumping of protons across the thylakoid membrane. The hydrogen ions are then used by ATP synthase to produce ATP through chemiosmosis where the hydrogen ions diffuse from the thylakoid space to the stroma of the chloroplast. Electrons in photosystem I are also excited through using the energy in the absorbed light and used to then reduce NADP+ into NADPH, which are used in the light independent reaction. Through more light absorbed, more electrons can be excited and produce oxygen through breaking up water into hydrogen ions and oxygen molecules, and as more oxygen is produced, the Cabomba plant produces more bubbles as well. [2][3]
The accuracy of the results is quite high as we can see from previous experiments that the results of this experiment is very similar to other experiments, where wavelengths of light which are similar to the colour of the leaf give the lowest rates of photosynthesis. [4] The precision of the experiment was quite low as the uncertainty of the equipment that was used ranged from 5% to 16%, showing us that the uncertainty was incredibly high due to the equipment not being very precise. Furthermore, the reliability of the data is not very high as we can see the standard deviation values for each result is quite higher, ranging from 6.9 - 25.2.