Question7 Photosystem.ll contains one of the most amazing enzyme activities on E

Question

Question7 Photosystem.ll contains one of the most amazing enzyme activities on Earth. What makes it so amazing? OIt catalyzes the formation of ATP from ADP using the energy of the proton gradient (photophosphorylation) It converts the energy stored in reduced intermediates to formation of a proton gradient. O It can catalyze the oxidation of water to 02. O It catalyzes the incorporation of CO2 into organic molecules, making it possible to synthesize sugars and other biological molecules that sustain most of life on Earth. Question 8 Which of the following statements is NOT true regarding our relationship to photosynthesis? For glycolysis to proceed in the absence of 02. NADH must be reoxidized to NAD+. This takes place during photosynthesis. Aerobic respiration requires 02, which is produced during photosynthesis. Most photosynthetic organisms fix CO2 reducing it to form sugars that we rely on for our source of energy and carbon. None of the above (i.e. all of the above are true.)

Explanation / Answer

Ans 7. It can catalyse the oxidation of water to O2.

Photosystem II (PS II) is actually a protein complex, that is quite important for photochemistry of an important process called, photosynthesis. During this process, the water-plastoquinone oxido reductase enzyme (located in the thylakoid membrane) utilizes the sun energy, helps in the splitting of water molecule and production of the molecular oxygen and plastoquinol. PS II utilizes the cholorphyll a molecule, that has capability to absorb 680 nm of light, that is why it has been abbreviated as P680.

PS II is the only process in most of the plants, algae and cyanobacteria for oxygen production. PS II also utilizes the PS I to produce the reduced form of NAD and ATP, which is use for the carbohydrate synthesis through the Calvin cycle.

Ans 8. The first option, For glycolysis to proceed in the absence of O2, NADH must be reoxidised to NAD+. This takes place during photsynthesis.

In aerobic organisms, oxidation of food is completed is completed through:

Out of above 4 steps, the last 3 steps requires oxygen. In aerobic organisms too, glycolysis does not require any oxygen, at the expense of 2 ATP, 4 ATP are paid. It is not true that NADH must be reoxidized to NAD+?.

The site of glycolysis is cytoplasm and for the next 3 processes listed above, mitochondria is required.

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