Explanation:

Photosynthesis is a process by which green plants and some other organisms use sunlight, carbon dioxide, and water to synthesize foods with the help of chlorophyll pigment. The process of photosynthesis is divided into two parts - light-dependent reactions and light-independent reactions.

The light reactions occur in the thylakoid membranes of the chloroplasts and involve the absorption of light energy by the pigments like chlorophyll and the conversion of that energy into chemical energy in the form of ATP and NADPH. The dark reactions, on the other hand, occur in the stroma of the chloroplasts and are also known as the Calvin cycle.

Dark reactions in photosynthesis:

The dark reactions or the light-independent reactions in photosynthesis are so called because they do not require the presence of light energy to occur. These reactions can occur in the absence of light, but they do require the products of the light-dependent reactions, i.e., ATP and NADPH, to proceed. The dark reactions involve the fixation of carbon dioxide into organic molecules like glucose, which can be used as a source of energy by the plant.

The dark reactions also involve the enzyme RuBisCO, which is responsible for catalyzing the reaction between carbon dioxide and ribulose 1,5-bisphosphate (RuBP). The reaction produces two molecules of 3-phosphoglycerate, which is then converted into other organic molecules like glucose and other carbohydrates.

Conclusion:

In conclusion, the dark reactions in photosynthesis are called so because they do not depend on light energy to occur. They can occur in the absence of light, but they do require the products of the light-dependent reactions to proceed. The dark reactions involve the fixation of carbon dioxide into organic molecules and are essential for the synthesis of glucose and other carbohydrates, which serve as a source of energy for the plant.

Photosynthesis is a process by which green plants and some other organisms convert light energy into chemical energy stored in the bonds of glucose or other organic compounds. Photosynthesis occurs in two stages: the light-dependent reactions and the light-independent reactions. The light-dependent reactions occur in the thylakoid membranes of chloroplasts and produce ATP and NADPH, which are used in the light-independent reactions. The light-independent reactions occur in the stroma of the chloroplasts and use the ATP and NADPH produced in the light-dependent reactions to fix carbon dioxide into glucose.

The light-independent reactions are also known as the Calvin cycle or the dark reactions because they do not require light energy to occur. The dark reactions can occur at any time, day or night, as long as the necessary enzymes and substrates are present.

Why is the dark reaction in photosynthesis called so?

The dark reaction in photosynthesis is called so because it does not depend on light energy. The term "dark" in this context does not mean that the reactions only occur in the dark. Instead, it refers to the fact that the reactions can occur in the absence of light. The dark reactions can occur during the day or night, as long as the necessary enzymes and substrates are present. The dark reactions use the ATP and NADPH produced in the light-dependent reactions to fix carbon dioxide into glucose.

Conclusion

The dark reaction in photosynthesis is an important process that occurs in the stroma of chloroplasts in green plants and some other organisms. The term "dark" in this context refers to the fact that the reactions do not require light energy to occur, and can occur at any time, day or night, as long as the necessary enzymes and substrates are present.