Question

ATP formation during photosynthesis is
A) Phosphorylation
B) Photophosphorylation
C) Oxidative phosphorylation
D) None of the above

Answer 1

Hint: ATP stands for Adenosine Triphosphate. It is the energy currency of the cell. In photosynthesis, ATP molecules are formed by an electron transport system.

Complete Answer:
Photosynthesis is the process by which plants prepare their own food in the presence of sunlight and chlorophyll.
This process has two pathways: light reaction and dark reaction.
1) Light reaction is the light dependent reaction which produces energy whereas dark reaction is the energy consuming reaction in which light is not the limiting factor.
- Both the pathways all together work for synthesis of glucose and energy molecules ATP and NADP.
- In photosynthesis, the electron transport system generates hydrogen ions. This hydrogen ion converts ADP and inorganic phosphate to ATP. This flow of electrons is called photophosphorylation.
- Photophosphorylation can be defined as the process by which light is converted to chemical energy by producing ATP.
2) In phosphorylation- It involves addition of phosphate to organic compounds.
3) In oxidative phosphorylation- It mostly takes place in mitochondria. In this the cells use enzymes to oxidise nutrients. This releases chemical energy in the form of ATP. All aerobic organisms carry out oxidative phosphorylation.

Thus the correct answer is (B). ATP is produced by photophosphorylation.

Note: Photosynthesis occurs in the thylakoid of the chloroplast. Oxidative phosphorylation takes place in the mitochondria. The ATP formed in the light reaction is utilised in making glucose in the dark reaction of photosynthesis.