How Chlorophyll Reflects Green Light During Photosynthesis
Green plants are also known as autotrophic plants because they are reported to contain a green-coloured photosynthetic pigment called chlorophyll, which is found in the chloroplast of plants. Plants are called photoautotrophs because they are capable of producing their own food through photosynthesis. The food synthesised by plants is stored in the form of starch. Green plants absorb carbon dioxide and release oxygen. Thus, plants help us to survive by providing oxygen to breathe in.
Why are Plants Green?
The integral part of a plant is the leaves, along with the other parts like the stem and root. Leaves are capable of performing photosynthesis with the aid of a primary pigment, chlorophyll which imparts green colour to the plants. The process of photosynthesis involves the conversion of light energy to chemical energy.
Plants have different pigments with different colours. The green pigment is known as chlorophyll which absorbs light. There are two types of chlorophyll, one is chlorophyll A which is the main pigment that takes part in the electron transport, and the other is chlorophyll B, which is the accessory pigment. They are reported to absorb light from 400-650nm.
Chlorophyll A can absorb blue light of wavelength 430 nm and red light of wavelength 662 nm. However, it is unable to absorb green light of wavelength 550 nm and thus reflects the green light. Due to the reflection of the green colour, the leaves on the plant come out green, and that is why the leaves are green.
Colourful Leaf Plants
The most colourful times of the year are spring and summer. Bright-coloured leaf plants blossom, and a sea of colour appears everywhere. There are different types of colourful leaf plants. The examples are discussed below.
The first is the hostas. This popular garden plant has large green leaves with thick white borders with numerous patterns and textures. The ‘Fire Island’ variety of hostas has luminous yellow leaves. The second is the Coleus which has interesting textures and colours ranging from reds, pinks, and yellows, to mixes of brilliant hues. They love the sun, and it appears bright during summer.
The Black Dragon variety has deep burgundy leaves with ruffled edges. Amaranthus Tricolour grows throughout the year; they appear in yellows, reds, and orange colours. It grows well during summer. The coral bells are low-growing shrubs that have purple to orange leaves.
Why are Green Plants Called Producers?
Green plants are called producers because they have the capability to produce their own food in the presence of sunlight through the process of photosynthesis. Green plants can prepare food from simple inorganic substances like carbon dioxide and water. During this process, energy in the form of glucose is released, which is used by the plants for survival, growth and reproduction.
Green plants are called autotrophs as they can manufacture their food from raw materials present in the surroundings like carbon dioxide and water. During the process of photosynthesis, plants consume carbon dioxide and release oxygen gas which is consumed by us. The steps of photosynthesis are discussed below.
Step 1: Absorption of light energy from the sun by chlorophyll.
Step 2: Conversion of light energy to chemical energy.
Step 3: The splitting of a water molecule into hydrogen and oxygen.
Step 4: Carbon dioxide is reduced to glucose.
Why are Leaves Green?
The green pigment present in leaves is chlorophyll which is contained in the thylakoid membranes of chloroplasts. There are five types of chlorophylls: chlorophylls a, b, c, and d, and a related molecule bacteriochlorophyll that is exclusively found in prokaryotes. It is present in the plasma membrane of bacteria.
The structure of chlorophyll molecules contains a hydrophobic tail that is inserted into the thylakoid membrane and a porphyrin ring head that is mainly responsible for absorbing light. Chlorophyll a is the main component, and the rest are accessory pigments. The accessory pigments help in absorbing a broader range of wavelengths so that more energy is captured from sunlight.
Interesting Facts
Green plants are called photoautotrophs because they can make their own food through the process of photosynthesis, which converts carbon dioxide and water in the presence of light to oxygen and energy. Chlorophyll assists this process by absorbing light energy.
Important Questions
1. What is the importance of green plants?
Ans: As the primary producers of the ecosystem, green plants are involved in producing food for consumers. Green plants are essential for maintaining the planet's carbon dioxide and oxygen equilibrium.
2. What are carotenoids?
Ans: Plants produce the yellow, orange, and red pigments known as carotenoids. The carotenoids alpha-carotene, beta-carotene, lutein, zeaxanthin, and lycopene are the most prevalent.
Key Features
The leaves of the plants appear green because of the presence of the green pigment Chlorophyll.
Chlorophyll plays a significant role in photosynthesis by absorbing light energy from the sun. Chlorophyll A mainly absorbs light strongly within the blue and red portions of the spectrum.
The green leaves can absorb light of all wavelengths except the wavelength of green light, i.e. the wavelength of 550nm. This green wavelength of light is reflected by the plant.
FAQs on Why Are Plants Green in Sunlight
1. Why are plants green?
Plants are green because they contain the pigment chlorophyll, which reflects green light while absorbing red and blue light for photosynthesis.
- Chlorophyll is located in the chloroplasts of plant cells.
- It absorbs mainly red and blue wavelengths from sunlight.
- Green wavelengths are reflected back to our eyes, making plants appear green.
2. What is chlorophyll and what does it do?
Chlorophyll is a green pigment in plants that absorbs light energy to drive the process of photosynthesis.
- Found inside chloroplasts in plant cells.
- Absorbs mainly red and blue light.
- Converts light energy into chemical energy stored in glucose.
3. Why does chlorophyll reflect green light?
Chlorophyll reflects green light because it does not efficiently absorb green wavelengths in the visible spectrum.
- It strongly absorbs red and blue light.
- Green light is mostly reflected or transmitted.
- The reflected green light reaches our eyes.
4. How does photosynthesis make plants green?
Photosynthesis makes plants green because it requires chlorophyll, the green pigment responsible for capturing light energy.
- Chlorophyll is essential for the light-dependent reactions.
- It absorbs sunlight to produce ATP and NADPH.
- Its presence gives leaves their green color.
5. Are all plants green?
Not all plants are entirely green, but most contain chlorophyll at some stage of their life cycle.
- Some plants have red, purple, or yellow pigments like anthocyanins and carotenoids.
- These pigments can mask the green color of chlorophyll.
- Non-photosynthetic plants may lack chlorophyll.
6. Why do leaves change color in autumn if chlorophyll is green?
Leaves change color in autumn because chlorophyll breaks down, revealing other pigments.
- Shorter days reduce chlorophyll production.
- Carotenoids show yellow and orange colors.
- Anthocyanins can produce red and purple shades.
7. What part of the plant cell makes plants green?
The chloroplast is the part of the plant cell that makes plants green because it contains chlorophyll.
- Chloroplasts are specialized organelles.
- They contain internal membranes called thylakoids.
- Chlorophyll is embedded in the thylakoid membranes.
8. Why don’t plants absorb green light?
Plants do not efficiently absorb green light because chlorophyll molecules are structured to absorb red and blue wavelengths more effectively.
- Light absorption depends on pigment structure.
- Green wavelengths are not strongly absorbed.
- Reflected green light determines leaf color.
9. Do algae and other photosynthetic organisms appear green for the same reason?
Yes, many algae appear green because they also contain chlorophyll for photosynthesis.
- Green algae have chlorophyll similar to plants.
- Some algae also contain accessory pigments like fucoxanthin or phycobilins.
- Different pigments can change their overall color.
10. Is green the most efficient color for photosynthesis?
Green is not the most efficient color for photosynthesis because chlorophyll absorbs red and blue light more effectively.
- Red light drives strong photosynthetic activity.
- Blue light supports both photosynthesis and plant growth.
- Green light is mostly reflected.
