Question

Where does the Dark reaction of photosynthesis occur?
A. Granal thylakoid membranes
B. Stroma lamellae membrane
C. Stroma outside photosynthesis lamella
D. Periplastic space

Answer 1

Dark Reaction of Photosynthesis is a series of chemical reactions which involves the conversion of carbon dioxide and other compounds to glucose. Dark reactions utilize products of light reactions but do not utilise light in the reaction.

Complete answer:
In dark reaction, the plant utilizes carbon dioxide and Adenosine Triphosphate (ATP) and Nicotinamide Adenine Dinucleotide Phosphate (NADPH) from light reaction to produce glucose. It is called a dark reaction because it does not utilize direct light but products from the light reactions.
The light reaction occurs in the Granal thylakoid membranes where photolysis occurs and NADP is converted to NADPH.
The dark reaction occurs in the stroma of the chloroplast specifically outside the photosynthetic lamellae of the chloroplast. The stroma contains essential enzymes for the dark reaction to occur. Therefore, it is the site of the biochemical phase in photosynthesis.
So, the correct answer is “Option C”.

Additional Information:

Light reaction	Dark reaction
Occurs in presence of light.	Occurs in the presence or absence of light.
Photochemical phase	Biochemical phase
Site of reaction- grana of the chloroplast	Site of reaction- stroma of the photosynthetic lamella
NADPH is formed by accepting a hydrogen atom.	NADPH gives its hydrogen to carbon dioxide.
ATP and NADPH are the end products.	Glucose is the end product.
Photolysis occurs	Photolysis does not occur.

Dark reaction is also called Carbon- fixing reaction, which occurs without utilizing sunlight. It is also known as the Calvin Benson-Bassham cycle.

Note:
The dark reaction occurs in the stroma of the photosynthetic lamella since it contains all the required enzymes for the reaction to take place.