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Home › CBSE Class 11 (Science) › Biology › Photosynthesis in Higher Plants › Chlorophyll-a primarily absorbs:

Chlorophyll-a primarily absorbs:

ABlue + red (440 + 660 nm)
BGreen (525-575 nm)
CFar red (700-800 nm)
DUV (300-400 nm)
Answer & Solution
Correct answer: A. Blue + red (440 + 660 nm)
Chlorophyll-a is the primary pigment involved in photosynthesis. Its absorption spectrum reveals how much light of different wavelengths it absorbs. 1. **Visible Spectrum:** Photosynthesis utilizes light within the visible range ($400\text{ nm}$ to $700\text{ nm}$). 2. **Absorption Peaks:** Chlorophyll-a shows two distinct absorption peaks. The first peak is in the **blue-violet region** (around $430$-$440\text{ nm}$) and the second is in the **red region** (around $660$-$670\text{ nm}$). 3. **Reflection:** It reflects light in the **green region** ($500$-$600\text{ nm}$), which is why plants appear green to the human eye. Therefore, Chlorophyll-a primarily absorbs blue and red light at approximately $440\text{ nm}$ and $660\text{ nm}$, respectively.
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