Question

1. aWhat wavelengths of light worked best for the production of oxygen? Hypothesize why it was those particular wavelengths of light that produced the most oxygen.b)Why did using the full spectrum of light work best for the production of oxygen?c)Explain why an increase in carbon dioxide in the Habitation Unit would not result in greater production of oxygen. Your explanation should include a discussion on the light-dependent reactions and the Calvin cycle.d)Explain why a change in pH did not have an effect on the production of oxygen. What did a change in pH effect? The pH was being changed specifically in the stroma, why does this mean that the change in pH would have that effect but not affect oxygen?e)Why did the addition of Atrazine reduce the production of oxygen? If Atrazine blocked the movement of electrons from photosystem I instead of photosystem II, should you expect different results?

Answer 1

a) 680nm wavelength is the region of the red light in the spectrum where maximum photosynthesis takes place and oxygen is produced.

b)  The light from the sun consists of green, yellow and orange spectrum which ae used least by the plants and most of the photosynthetic activity takes place in red and blue frequencies.Primitive bacteria evolved in the earlier days used yellow, green and orange for photosynthesis, thus leaving out the red , blue and green frequencies which was used by complex plants for photosynthesis leaving the plants green coloured.

c)When concentration of carbondioxide increases in the atmosphere there is greater production of oxygen because in dark reactions or light independent reactions rate of photosynthesis increase thereby releasing more oxygen whereas in light dependent reactions it is the viceversa.

d) Changes in pH affects the alkalinity but does not affect the oxygen production.pH in the Thylakoid space decreases at 20 dergrees but in stroma pH increases by 1.5

e)Atrazine an–inhibiting herbicide  blocks  with photosynthetic electron transport,and prevents the oxygen production . This happens when Atrizine blocks the electron transport of PSI instead of PSII.