Question: why chlorophyll does not absorb ordinary light for photosynthesis

Jacinta Nzilani answered on 22 Jul 2025:

Hey there! 🌱👋

🌈 Why Doesn’t Chlorophyll Absorb “Ordinary Light” for Photosynthesis?

First, let’s define what we mean by “ordinary light.” Usually, that’s white light (like sunlight), which is a mix of all colors of visible light.

🟢 Chlorophyll Selectively Absorbs Light
Chlorophyll doesn’t absorb all parts of the visible spectrum equally:

✅ Absorbs best:

Blue light (~430–470 nm)

Red light (~660–680 nm)

❌ Reflects most:

Green light (~500–550 nm)

This is why leaves look green. Chlorophyll reflects green instead of absorbing it.

🔍 Why Not Just Absorb All Light?
Chlorophyll molecules are tuned to specific energy levels. The photons in blue and red light have just the right amount of energy to excite electrons in chlorophyll and start photosynthesis. ⚡🌿

Light that’s too low in energy (like far-red or infrared) won’t excite electrons enough.

Light that’s too high in energy (like UV) can damage the plant cells.

🧪 Scientific Insight:
Chlorophyll’s absorption pattern is based on its molecular structure, which determines which wavelengths of light it can absorb.

🌞 In Summary:
Chlorophyll doesn’t absorb all of “ordinary light” because it’s specialized to absorb only the blue and red parts, which have just the right energy to power photosynthesis! 🧪🌿