The main photosynthetic pigment in chloroplasts is the blue-green chlorophyll a. Accessory pigments are yellow-green chlorophyll b, yellow-brown xanthophylls, orange carotenoids and phaeophytin which is a grey-brown pigment.The role of the pigments is to capture light energy by electron excitation. When light is absorbed by a pigment its electrons are excited to a higher energy level. The electrons can then take part in redox reactions transferring the light energy to other reactions. Different pigments absorb light of different wavelengths ensuring the plant absorbs as much light as possible. Chlorophylls a and b absorb red and blue light and reflect green light, so they appear green.
Photosynthetic pigments
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Specification: AQA Biology (7402), A-level, 3.5.1 Photosynthesis. Topic: Energy for Biological Processes.
Key terms in this lesson
- hormone
- A chemical messenger, secreted by an endocrine gland directly into the blood, that travels to target cells bearing complementary receptors and brings about a response.
- insulin
- A hormone secreted by the beta cells of the islets of Langerhans in response to a rise in blood glucose concentration, which lowers blood glucose by stimulating cells to take up and use or store glucose.
More in Energy for Biological Processes
- ATP
- Chloroplasts
- Photosystems
- Cyclic Photophosphorylation
- Non-cyclic Photophosphorylation
- Chemiosmosis
- Calvin Cycle
- Limiting Factors of Photosynthesis
All 17 lessons in Energy for Biological Processes · All AQA A-level Biology topics