Chlorophyll
Definition
Chlorophyll is the green pigment found in chloroplasts that is essential for photosynthesis. It absorbs light energy, particularly from red and blue wavelengths, and reflects green light (making plants appear green). Chlorophyll a is the primary pigment, while chlorophyll b is an accessory pigment.
Key Points for NEET
- 1Located in thylakoid membranes of chloroplasts
- 2Chlorophyll a absorbs red (660nm) and blue (430nm) light
- 3Has a porphyrin ring with magnesium at center
- 4Chlorophyll a and b differ in one side group
- 5Works with accessory pigments (carotenoids, xanthophylls)
Example
Leaves turning yellow in autumn as chlorophyll breaks down and reveals other pigments
Asked in NEET
Common Mistakes to Avoid
- ✗Confusing chlorophyll a (primary, blue-green) with chlorophyll b (accessory, yellow-green)
- ✗Thinking chlorophyll absorbs green light — it reflects green, absorbs red and blue
- ✗Forgetting that carotenoids and xanthophylls are accessory pigments that broaden absorption range
Quick Revision Notes
- ⚡Chlorophyll a (P680 in PS II, P700 in PS I) is the primary photosynthetic pigment
- ⚡Absorption peaks: Chl a = 430nm (blue) + 660nm (red); Chl b = 455nm + 640nm
- ⚡Porphyrin ring with Mg²⁺ center; phytol tail anchors it in thylakoid membrane
- ⚡Autumn leaf color: chlorophyll degrades revealing yellow carotenoids and red anthocyanins
Related Terms
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More Plant Biology Definitions
Photosynthesis
Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy (usually from the sun) into chemical energy stored in glucose. This process uses carbon dioxide and water as raw materials and releases oxygen as a byproduct. It occurs in chloroplasts and involves light-dependent and light-independent reactions.
Xylem
Xylem is the vascular tissue in plants that conducts water and dissolved minerals from roots to stems and leaves. It consists of tracheids, vessel elements, xylem fibers, and xylem parenchyma. The movement of water through xylem is driven by transpiration pull and root pressure.
Phloem
Phloem is the vascular tissue that transports organic nutrients (mainly sucrose) from leaves to other parts of the plant. It consists of sieve tubes, companion cells, phloem fibers, and phloem parenchyma. Unlike xylem, phloem can transport in both directions (bidirectional).