Biology · Photosynthesis in Higher Plants · NEET
It takes place in the chloroplast. The chloroplast is a plastid found mainly in the mesophyll cells of the leaf. Inside the chloroplast there are two working zones: the membrane system (grana and stroma lamellae) traps light and makes ATP and NADPH, and the stroma (matrix) makes sugar. So the answer NEET wants is the chloroplast, not just the leaf.
The mesophyll cells. NCERT says mesophyll cells in the leaf have a large number of chloroplasts, so they do most of the photosynthesis. The chloroplasts line up along the walls of the mesophyll cell to catch the best amount of incident light.
No. Leaves are the main site because they are full of mesophyll cells, but NCERT clearly states photosynthesis also takes place in other green parts of the plant, such as green stems and green sepals. Any green part with chloroplasts can do photosynthesis.
There is a clear division of labour. The membrane system (grana and stroma lamellae) does the light reaction: it traps light and makes ATP and NADPH. The stroma does the dark reaction (carbon reactions): its enzymes use ATP and NADPH to make sugar, which then forms starch. This split is a common NEET point.
Be careful here. In C3 plants the whole Calvin cycle runs in mesophyll chloroplasts. In C4 plants, mesophyll cells only do the first CO2 fixing (using PEP), and the Calvin cycle runs in the bundle sheath cells. So mesophyll is where photosynthesis starts in both, but in C4 the sugar-making step shifts to bundle sheath cells.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
In the chloroplasts, which are present in large numbers in the mesophyll cells of green leaves and in other green parts of the plant.
Because mesophyll cells contain a large number of chloroplasts, and the chloroplasts align along the cell walls to receive the best amount of light.
The membrane system, that is the grana and stroma lamellae (thylakoids). This is where light is trapped and ATP and NADPH are made.
The stroma (matrix). Its enzymes use ATP and NADPH to fix CO2 into sugar, which then forms starch.
Yes. NCERT states it also occurs in other green parts of the plant, such as green stems, because these parts also contain chloroplasts.
