Question:

Dark reaction occurs only at night in the stroma of chloroplast. CO fixation occurs only during C cycle.

Updated On: Aug 15, 2022

If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false

Hide Solution

Verified By Collegedunia

The Correct Option is D

Solution and Explanation

Dark reaction is also known as lightindependent phase. Unlike, light reaction, it does not require light as an essential factor. Thus can takes place both in the presence or absence of light. The term dark reaction does not mean that it takes place only in dark period or at night. $CO_2$ fixation occurs in both $C_3$ and $C_4$ cycle. In $C_3$ cycle, $CO_2$ is added by the enzyme, RuBisco to a 5 carbon compound RuBP that is converted to 2 molecules of 3-carbon PGA. In $C_4$ cycle the first product of $CO_2$ fixation (takes place in mesophyll) is a 4-carbon compound, oxaloacetic acid. It is seen in some tropical plants.

Was this answer helpful?

Questions Asked in AIIMS exam

View More Questions

Concepts Used:

Photosynthesis in Higher Plants

Processes Of Photosynthesis in Higher Plants:

Photosynthesis in higher plants involves the following processes:

Light Reaction
Dark Reaction

Light Reaction:

This phenomenon occurs in the presence of light.
The pigment absorbs light and produces energy in the form of ATP.
The process involves- absorption of light, water splitting, the release of oxygen, and formation of ATP and NADPH.

Dark Reaction:

This process occurs in the absence of light in the stroma of the chloroplasts. The following cycles are involved in the process:

Calvin Cycle (C3 Cycle)
C4 Cycle (Hatch and Slack Pathway)