Question

Biosynthetic phase is also known as
(a)Dark reaction
(b)Light reaction
(c)Photochemical phase
(d)Light-dependent phase

Answer 1

Hint: Biosynthetic phase is the phase of photosynthesis where the chemical products of the light reaction are used to synthesize the actual food i.e. glucose, in the higher plants.

Complete answer:
The process of photosynthesis, in higher plants, occurs in two phases – light and dark, and the dark phase or dark reaction is also known as the biosynthetic phase. In general, it can be understood that the first phase is for converting the light energy into chemical energy and this chemical energy is further used in the formation of the desired form of food in the second phase. The events or reactions occurring during the light phase are mainly photolysis and synthesis of ATP and NADPH. As these are directly driven in the presence of light and obtain necessary energy from the sunlight, they are called light reactions, light-dependent phase, or photochemical phase. In the second phase of photosynthesis i.e. the dark phase, the chemical products, ATP and NADPH formed during the light reaction, are used to make glucose in the stroma of the chloroplasts via Calvin Cycle. The reactions are not directly dependent on the presence of light and hence these are called dark reaction, light-independent reaction, or biosynthetic phase. The Calvin cycle has been shown below -

So, the correct answer is 'dark reaction'.
Note: Electrons and protons play a crucial role during the light reaction. When sunlight is absorbed by the photo-pigments, the absorbed light energy is used in the photolysis of water and to drive electrons to generate NADPH. The same light energy is used to drive protons across a membrane and when these protons return through ATP synthase, the ATP molecule is synthesized.