Tag: botany

Photolysis, as the name suggests, is the breakdown of water in the presence of sunlight to form H⁺ and  O₂ and electron. This takes place during the light phase of photosynthesis in the PS-II. This creates the oxygen which is the net product of photolysis.

Chemiosmotic hypothesis explains how ATP is synthesized in the chloroplast. ATP synthesis is linked to the development of a proton gradient across the membrane of the thylakoid of chloroplast and proton accumulation is towards the inside of the membrane i.e., in the lumen. Source of protons within the chloroplasts is water. The splitting of water molecule takes place on the inner side of the membrane and so the protons (hydrogen ions) are produced, they accumulate within the lumen of the thylakoids. Thus, the correct answer is option A.

In the process of photosynthesis, water acts as a stable oxygen donor. To prove the theory radioisotopic technique was used. 

A)In 1930, C.B.Van Niel proved that the sulphur bacteria use H$ _2$S and CO$ _2$ to synthesize carbohydrates.

The oxygen in photosynthesis is released from photolysis of water in which water get split into hydrogen ions oxygen in the presence of sunlight.

Photolysis as the name suggests is the process, which happens in the presence of light. Photolysis is the process of splitting of water molecule to liberate oxygen in the presence of light. It takes place in the light phase of photosyntehsis and closely in proximation of PS-II.

Photolysis means to break down of the water molecule in the presence of light into H$^+$ nascent oxygen and an electron this process constitute in the PS II and the electron release is utilized by it as the compensation of electrons given by it to PS I during the Z scheme.

During this process, the electrons in water are removed and passed to the reaction center chlorophyll. The associated hydrogen ions are released from the water molecule, and after two water molecules are thus split, the oxygen atoms join to form molecular oxygen (O ₂ ), a waste product of photosynthesis.

Robin Hill demonstrated Hill reaction in 1939. Hill's reaction proves that oxygen is evolved during the light requiring steps of photosynthesis. It is isolated in chloroplasts.

A. Ruben and Kamen used the radioactive isotope of oxygen ($^1$$^8$O) in water and found that O$ _2$ liberated in the process was isotopically labelled. On the contrary, when $^1$$^8$O in CO$ _2$ was used, the evolved O$ _2$ did not show radioactivity.