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UPSC Prelims 1982 · Environment · Nature’s Machinery
Chlorophyll is a/an
- (a) Halogen acid
- (b) A green pigment found in the plants
- (c) A chloro-organic compound
- (d) Element
Show the answer and explanation
Answer: (b) A green pigment found in the plants
Chlorophyll is the green pigment that absorbs red and blue light for photosynthesis.
The idea
A pigment is a substance that absorbs some colours of light and reflects others. Chlorophyll absorbs red and blue light and reflects green, which is why leaves look green.
Sunlight falls on a leaf → Chlorophyll absorbs red and blue → Green is reflected to our eyes → The absorbed energy drives photosynthesis
Why the others are wrong
(c) Chlorophyll contains no chlorine — “chloros” is Greek for pale green.
(d) It is a large organic molecule, not an element.
The trap
The name suggests chlorine, which is what (c) plays on.
Also know
Leaves hold other pigments too: carotenoids (yellow and orange) and anthocyanins (red and purple). When chlorophyll breaks down in autumn or in a ripening fruit, these colours show through.
🔒 Chlorophyll = green pigment, Mg at the centre, absorbs red + blue, reflects green.