Light absorption Flashcards
What is light?
Light is a form of electromagnetic radiation which travels in waves.
Visible light
Made up of a spectrum of different colours. Each colour of light has a different wavelength.
Colours wavelength from low to high
Violet, Indigo, Blue, Green, Yellow, Orange, Red.
When light comes into contact with a substance what will it’s fate be?
It will either be absorbed, reflected or transmitted.
Why is light needed for photosynthesis?
It is converted into chemical energy.
It is absorbed by pigments in the leaf, this energy generates ATP.
What are photosynthetic pigments?
They absorb particular wavelengths of light, the rest of the light is either reflected or transmitted.
Leaves contain several coloured pigments.
These pigments can absorb light energy are different wavelengths of light.
What object can be used to see the light spectrum?
Spectroscope
Why does many different pigments benefit a plant?
It allows the plant to absorb a wider range of wavelengths since each pigment present in the leaf absorbs light of a certain wavelengths.
Chlorophyll molecules
Two types chlorophyll a and b
Both absorb mainly red and blue light.
Chlorophyll a has an Rf value of 0.65
Chlorophyll b has an Rf value of 0.45
Accessory pigments
The carotenoids- carotene and xantophyll a.
They are responsible for absorbing light from regions which the chlorophyll doesn’t absorb.
Accessory pigments extend the wavelength of light absorbed by pigments.
Absorption spectrum
Graph which shows the wavelengths of light absorbed by each pigment.
Action spectrum
Graph which shows the rate of photosynthesis at different wavelengths.
Comparisons between absorption and action spectrums
The correlation between the two graphs is close therefore we can conclude that the pigments absorb the light for use in photosynthesis.
When the absorption line is lower than the action spectrum for a chlorophyll pigment then it is because the carotenoids are present there and they extend the wavelengths that are absorbed by the plant.
