Question

Dark reaction in photosynthesis is called so because
A. It can occur in dark alone
B. It does not require direct light energy
C. It cannot occur during day time
D. It occurs more rapidly at night

Answer 1

Hint: A process carried out by plants and few organisms that makes use of carbon dioxide, sunlight and water to prepare food is called photosynthesis. Conversion of carbon dioxide and different compounds results in the glucose formation resulting in the dark reaction in photosynthesis.

Complete answer:
Dark reaction of photosynthesis is also called Calvin cycle or light independent reaction or ${C_3}$ cycle. The site of the dark reaction is in the stroma of the chloroplast. These reactions utilise the usage of products released in the light reaction for regulation of function. This reaction occurs in almost all plants. ${C_3}$ plants tend to grow in areas where the intensity of sunlight is moderate. Therefore the dark reaction in photosynthesis is called so because it don ot directly depend on light energy.
Dark reaction of photosynthesis has distinct chemical reactions which help in the transformation of carbon dioxide and other compounds to form glucose. It utilizes the products of light reactions but does not utilise light in the reaction. In the dark reaction NADPH gives its hydrogen to carbon dioxide and glucose is the end product.

Hence, the correct answer is option (B).

Additional information:
The process which involves the conversion of inorganic carbon into organic compounds by the living organism is called carbon fixation. The process of carbon fixation is used in the process of photosynthesis. ${C_3}$plants tend to survive by ${C_3}$ carbon fixation. The process involves the conversion of carbon dioxide and ribulose phosphate into two molecules of $3$-phosphoglycerate.

Note: ${C_3}$ plants are called temperate plants and are referred to as light independent reactions in a process of photosynthesis. It is because they use ATP and NADPH formed in the light dependent reaction for their further chemical reaction.