DENDROLOGY

TREE PHYSIOLOGY

PHOTOSYNTHESIS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
In a chloroplast where are the enzymes of the Calvin cycle located?
A
Thylakoid membranes
B
Stroma
C
Grana
D
Outer membrane of chloroplast
Explanation: 

Detailed explanation-1: -Unlike the light reactions, which take place in the thylakoid membrane, the reactions of the Calvin cycle take place in the stroma (the inner space of chloroplasts).

Detailed explanation-2: -The enzymes in the Calvin cycle are functionally equivalent to most enzymes used in other metabolic pathways such as gluconeogenesis and the pentose phosphate pathway, but the enzymes in the Calvin cycle are found in the chloroplast stroma instead of the cell cytosol, separating the reactions.

Detailed explanation-3: -The initial reaction in carbon fixation. This reaction, in which carbon dioxide is converted into organic carbon, is catalyzed in the chloroplast stroma by the abundant enzyme ribulose bisphosphate carboxylase.

Detailed explanation-4: -What is stroma in a chloroplast? Stroma is the fluid-filled internal space of the chloroplasts which encircle the grana and the thylakoids. It contains chloroplast DNA, starch and ribosomes along with enzymes needed for the Calvin cycle.

Detailed explanation-5: -Stroma, in botany, refers to the colorless fluid surrounding the grana within the chloroplast. Within the stroma are grana (stacks of thylakoid), and the sub-organelles or daughter cells, where photosynthesis is commenced before the chemical changes are completed in the stroma.

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