Summary
Chlorophylls, carotenoids and xanthophylls absorb different wavelengths and widen the usable light spectrum.
In depth
Chlorophyll a, chlorophyll b, carotene, xanthophyll. Absorption spectra show where light is absorbed; the action spectrum shows photosynthetic rate by wavelength and matches absorption well.
Absorption spectra reveal peaks for chlorophyll in blue (430 nm) and red (660 nm). Carotenoids absorb blue-green and protect against photodamage by dissipating excess energy.
Example: chromatography Rf values differ: carotene runs furthest, then xanthophyll, chlorophyll a and b.
Pigments are separated by chromatography. Chlorophylls absorb red and blue, carotenoids (orange, yellow) absorb blue-green and protect against photodamage, phycobilins in red algae and cyanobacteria absorb green and let them live in deeper water. The absorption spectrum is for isolated pigment, whereas the action spectrum plots photosynthesis rate against wavelength, and the two match closely, as Engelmann's 1882 experiment with Spirogyra and aerotactic bacteria showed.
Antennae pigments gather light and pass energy to P680 or P700 reaction centres. Anthocyanins give red and purple colours and act as sunscreen. Pigments in leaves vary with light levels.
Example: red seaweeds at depth use phycoerythrin to capture the blue-green light that reaches there.
Frequently asked questions
What is Photosynthetic Pigments?
Chlorophylls, carotenoids and xanthophylls absorb different wavelengths and widen the usable light spectrum.
Which area of biology covers Photosynthetic Pigments, and how advanced is it?
Photosynthetic Pigments is one of the 56 topics in Plant Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Chlorophyll, Photosynthesis, Photorespiration.
Can you give an example of Photosynthetic Pigments?
Red algae have phycoerythrin to absorb blue-green light in deep water.
What should I learn before Photosynthetic Pigments?
Work through the Beginner topics in Plant Biology first, such as Plant Kingdom, Photosynthesis, Chlorophyll, then return to Photosynthetic Pigments. Intermediate topics assume the Beginner vocabulary.
What topics are related to Photosynthetic Pigments?
The closest topics to Photosynthetic Pigments are Chlorophyll, Photosynthesis, Photorespiration, Cyclic Photophosphorylation. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Photosynthetic Pigments?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Photosynthetic Pigments. To practise the whole of Plant Biology, use the Plant Biology quiz.
How is Photosynthetic Pigments different from Chlorophyll?
Photosynthetic Pigments: Chlorophylls, carotenoids and xanthophylls absorb different wavelengths and widen the usable light spectrum. Chlorophyll: The green pigment in chloroplasts that absorbs mainly red and blue light. Read both side by side and note what each one explains.
How should I study Photosynthetic Pigments step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Chlorophyll and explain the difference aloud. Finally, take the Plant Biology quiz and come back to this page for any question you miss.