Plants are living creatures that depend on themselves for food. The process that they use for creating their food is known as photosynthesis. This process requires a pigment called chlorophyll.
Both play significant roles in photosynthesis as they help absorb sunlight needed to produce carbohydrates.
- Chlorophyll a is the primary pigment in plants, algae, and cyanobacteria, capturing light energy during photosynthesis.
- Chlorophyll b is an accessory pigment, assisting chlorophyll in capturing light energy by broadening the absorption wavelength spectrum.
- Although both pigments play a role in photosynthesis, chlorophyll a is essential, while chlorophyll b supports its efficiency.
Chlorophyll A vs B
Chlorophyll a light absorbing, photosynthetic, primary pigment of chlorophyll. All plants algae, bacteria, cyanobacteria, and phototrophs contain chlorophyll a. Chlorophyll b a secondary pigment of chlorophyll. Possesses high absorption rate. It occurs in plants and green algae. It has low absorption rate.
|Parameters of Comparison||Chlorophyll A||Chlorophyll B|
|Definition||Chlorophyll A is the prime pigment used in photosynthesis. It captures sunlight.||Chlorophyll B is the additional pigment used in photosynthesis. It collects sunlight and passes it to chlorophyll A.|
|Range of absorption||430 mm to 660 mm.||450 mm to 650 mm.|
|Colour of absorption||This absorbs orange-red and blue-violet light.||This absorbs orange-red light.|
|Reflecting colour||Chlorophyll A reflects a blue-green colour.||Chlorophyll B reflects a yellow-green color.|
|Absorbing wavelength||It absorbs wavelengths 430 nm and 662 nm.||It absorbs wavelength 470 nm.|
|Structure||Chlorophyll A contains a methyl group.||Chlorophyll B contains an aldehyde group.|
|Molecular Weight||839.51 g/mol||907.49 g/mol.|
|Found in||It is found in algae, plants, and cyanobacteria.||It is found in algae and plants.|
|Quantity||¾ of total chlorophyll.||¼ of total chlorophyll.|
|Solubility in polar solvents||Low||High|
What is Chlorophyll A?
Chlorophyll A refers to the green pigment which helps absorb light and provide energy in photosynthesis. It is present in algae, cyanobacteria, and all plants.
Chlorophyll A is an essential pigment for plants as it plays an important role in photosynthesis. It helps in the electron transport chain during photosynthesis.
It also transfers light energy from the antenna to the photosystems P680 and P700. Here chlorophylls are found in the thylakoid membrane of the chloroplast.
The wavelengths responsible for violet-blue and orange-red colours are 429 nm and 659 nm, respectively.
It reflects bluegreen colour, which brings out the green colour in most plants.
Chlorophyll A has a chlorine ring. Here a magnesium ion is surrounded by four nitrogen atoms. It also consists of some side chains and hydrocarbon tails.
Hence, we can say that the basic role of Chlorophyll A is to absorb light from the orange-red and violet-blue colours of the spectrum and transfer this energy to the reaction center.
What is Chlorophyll B?
Chlorophyll B is a green pigment that helps in photosynthesis by collecting light energy and then passing it to chlorophyll A. It is present in plants and green algae.
The wavelengths responsible for violet and red colours are 455 nm and 642 nm, respectively.
It reflects a yellow-green colour. Chlorophyll B is present in most land plants’ light-trapping antenna in photosystem P680.
Hence, we can say that the main role of Chlorophyll B is to increase the absorption spectrum of organisms. This helps them to absorb more energy and helps organisms to convert more energy from the sun into chemical energy.
Main Differences Between Chlorophyll A and B
- ¾ of the total chlorophyll in plants constitutes Chlorophyll A. ¼ of the total chlorophyll in plants constitutes Chlorophyll B.
- Chlorophyll A is there in the reaction centre of the antenna array. Chlorophyll B controls the size of the antenna.
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Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.