Question

This is Tony. Tony is a somewhat rude and self-absorbed phytoplankton (ie, a photosynthesizing Single-celled organism) that lives in Dr. Wright's aquarium. On Tuesday. Tony was having a good day actively photosynthesizing in the presence of abundant light and Co. Suddenly his day took a turn for the worse when Dr. Wright cleaned his tank and occidentally flushed Tony down the drain (NO LIGHT. HIGH CO.J. Predict how the concentration of glyceraldehyde 3-phosphate (G3P) would change in Tony over the next minute or so. Select only ONE answer choice. Relative Concentration Relative Concentration Relative Concentration LOW Time Time Time From Question 5 above: Imagine Tony found himself suddenly in an outdoor sewage cesspool (HIGH LIGHT, VERY HIGH CO.,). Predict how the concentration of glyceraldehyde 3-phosphate (G3P) would change in Tony over the next minute or so in these new conditions. Select only ONE answer choice. LIGHT Relative Concentration Relative Concentration Relative Concentration Time 7 Why is water (H,0) necessary for photosynthesis to occur? Select only ONE answer choice. A Water is the primary source of H'lons to convert NADP-NADPH B. O, is a necessary product of splitting H,O, which acts as the e-acceptor at the end of the photosynthetic electron transport chain. C. Water is the initial energy source which activates and oxidizes Photosystem II. D. Water is split by Photosystem Il after Photosystem Il is activated by light, providing electrons for the photosynthetic electron transport chain. E. None of the above; H,O is necessary in respiration, but not in photosynthesis. 8 Some photosynthetic organisms contain chloroplasts that lack Photosystem II, yet are able to survive. The best way to detect the lack of Photosystem Il in these organisms would be to Select only ONE answer choice. A determine if they have thylakoids in the chloroplasts B. test for CO, fixation in the dark C. test for production of either sucrose or starch D. test for production of o, in the light

Answer 1

5. Option A

Explanation: Though the carbon fixation that takes place in Calvin Cycler is called the Dark reaction or Light independent reaction, the conversion of CO₂ to G3P requires energy in the form of NADPH and ATP which have short lived stability and these energy rich molecules come from the light dependent reactions, hence the concentration of G3P will start to dip within few minutes in the absence of light despite the presence of high CO₂  concentration as the energy molecules like ATP and NADPH will be depleted quickly.

6. Option A

Explanation: As it is noted in the above explanation, i.e Q5, the G3P synthesis in the light independent reaction of Calvin cycle requires ATP and NADPH from the light reaction to take place, hence once light is provided the ATP and NADPH synthesis is started in the light dependent reaction and is available for carbon fixation in the Calvin cycle, hence G3P concentration will start to increase wth few minutes once the phytoplankton in a high light and CO₂ concentration

7. Option D. Water is split by photosystem II after photosystem II is activated by light, providing electrons for the photosynthetic electron transport chain.

Explanation: The light reaction phase of photosynthesis requires electron as the incidence of photons on the Photosystem II excites the electrons and raises their energy level thus providing electrons for the electron transport chain, hence the electrons for this process need to be replenished in the photosystem II, this where water is subjected to a process called photolysis i.e splitting of water, and the resulting electrons and photons are utilized to power the various photosynthetic processes and O₂ is also released as a bi product.

8. Option D. Test for production of oxygen in light

Explanation: There are organisms that perform photosynthesis without the presence of photosystem I,I where O₂ is the end product, for example anoxygenic photosynthesis takes place in certain green sulfur bacteria and purple bacteria which have sulphur as their reducing agent instead of Oxygen, hence we can detect photosynthetic organisms that lack photosystem II by detecting the absence of oxygen in these organisms in the presence of light. These organisms have chlorophyll similar to plant chlorophyll but have different wavelength absorption ranges and have other end products like sulphur from Hydrogen sulphide rather than oxygen from water.