Question

The electron from photosystem-II goes to photosystem-I and finally taken up by NADP leaving an electron hole in photosystem-II. This electron hole in photosystem-II is filled by the electron released form

• A. $C{O}_2$
• B. $H_{2}O$
• C. chlorophyll
• D. light

Answer 1

Answer: (B)

Photo chemical reaction or light reaction, takes place in grana of chloroplast. According to Arnon, light energy is converted into chemical energy and is stored in ATP. This process is known as photophosphorylation. NADP; $2H$ is formed as hydrogen donor. Photochemical reaction include two photo acts: photosystem-I and photosystem-II, which are called as cyclic and non-cyclic photophosphorylation respectively. In cyclic photophosphorylation electron released from $P_{700}$ return to $P_{700}$ cyclic manner while in photosystem-II electron released from $P_{680-690}$ does not return, but is passed on to NADP with helps of photosystem-II. During the photo act continued supply of electron is made by oxygen evolving complex (4 manganese ion $M{n}^{+2},M{n}^{+3},M{n}^{+4}$ and $M{n}^{+5}$ ), The complex oxidises two molecule of water to form one molecule of $O_{2}4H^{+}$and $4\bar{e}$, i.e., photolysis of water takes place.