How Do Pigments Influence Biological Processes?
Are you a biology fanatic? Have you ever been fascinated about how the science behind every living thing works? Well, biology is all about that. With biology in our lives, we get to study and learn all about plants, animals, humans, basically everything! One such fascinating topic amongst many pigments. Interested to learn more about them? Let's get started then. Now, what are pigments? This is one of the basic questions to arise in your minds. They are biochromes or substances that are produced by any living organism that has color. You can also call them color pigments. You can classify them into two major types as plant pigments and flower pigments. The most common pigment that you can see around you every day is the green pigment in plants.
It is a result of the chlorophyll present in plants. You can see the microscopic view of it in the image below.
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What is the Meaning of Pigment?
When we talk about what is the principal pigment of plants, in simple terms, you can say that pigments are the components that give color to every living thing on this planet. In plants, you can see these pigments in leaves, and in flowers, you can see them in their petals. Not just in plants and flowers, pigments are present in animals as well. We need to understand the reason behind it.
So what is pigment biology? It is the science due to which color pigments are produced by living organisms. They are produced due to color absorption by a particular living organism from its environment. Different organisms absorb different wavelengths of light and this results in the variations that are found in color pigments.
What is Meant by Pigment Used in Industrial Purposes?
Now, what are pigments from the Industrial perspective? Pigments used for industrial purposes are the insoluble solid substances that are obtained by mixing two or more compounds. They are used in paints, cosmetics, inks, fabrics, plastics, and many other industries. They can be classified into 2 types as;
Organic Pigments
They consist of carbon chains and rings in their structure but may have some type of metallic element in their composition that is added to stabilize the parent structure.
Inorganic Pigments
They consist of chemical compounds that do not have carbon. They usually consist of metallic salts that are formed due to interaction between compounds.
Types of Pigment in Plants
There are different types of pigments that a plant can have. The variations in plant pigments are due to the different wavelengths of light that they absorb. The plants that have strong color pigments are also used to manufacture natural dyes. So what are the types of plant pigments? Let’s have a look at them.
Now, as per the earlier discussion, we have the answer to the question “What is the main pigment in plants?”. The answer to it is chlorophyll, which is the green pigment in plants. It is the most abundant plant pigment in the world. So what are some of the other plant pigments or what pigments are found in plants?
Apart from the green pigment in plants, Carotenoids, Flavonoids, and Betalains are some of the other plant pigments. When it comes to fruits and vegetables, color pigments are present in them too. To name a few, the yellow pigment found in them is called Lutein whereas the red pigment in plants is Lycopene.
Anthocyanins are water-soluble pigments that are present in the flower petals of different species.
The green pigment in plants has variations depending upon the living organism that they occur in. The four types of chlorophyll in plants are chlorophyll-a, b, c, d. These chlorophyll pigment types are found in different types of algae, higher plants, and cyanobacteria spending upon the wavelength of light that they absorb.
The Types of Chlorophyll in Algae are Categorized as Follows
Type-a in algae.
Type-b in green algae.
Type-c in brown algae.
Type-d in red algae.
Importance of Pigments
So far, we have discussed the answers and facts for questions like “what are pigments?” and “what is meaning of pigment?”. We are yet to discuss the question “what do pigments do for plants?”. So let’s get started.
Chlorophyll or the green pigment in plants is one of the most important components that the plants need to prepare their food. The absorption of light that results in the generation of the green pigment helps the plants to carry out photosynthesis and to prepare their food.
Fun Facts
Are you aware that leaves change their color? Yes, that’s right. Due to the change in season, especially during Autumn, it becomes difficult to absorb most of the sunlight for leaves as the days get shorter. The chlorophyll supply needed for plants to make food is not met and as a result, they start to use the chlorophyll that was stored all year along.
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FAQs on Understanding Biological Pigments: Meaning, Types & Importance
1. What is a biological pigment in the context of the NCERT syllabus?
A biological pigment is a substance produced by living organisms that has a specific colour due to selective colour absorption. In biology, these molecules absorb certain wavelengths of light and reflect others, which we perceive as colour. Their primary importance lies in their ability to capture light energy, as seen with chlorophyll in photosynthesis, or to provide coloration for functions like camouflage, as seen with melanin in animals.
2. What are the major types of pigments found in plants and their characteristic colours?
Plants contain several classes of pigments, each with a distinct role and colour. The main types are:
- Chlorophylls: These are the primary photosynthetic pigments, responsible for the green colour of leaves. They absorb blue and red light most effectively. The two main types are chlorophyll a and chlorophyll b.
- Carotenoids: These are accessory pigments that appear yellow, orange, or red. They absorb light in the blue-violet region. This class includes carotenes (orange) and xanthophylls (yellow).
- Anthocyanins: These water-soluble pigments are responsible for most of the red, purple, and blue colours in flowers, fruits, and autumn leaves. Their colour depends on the pH.
3. What is the specific role of pigments in the process of photosynthesis?
In photosynthesis, pigments function as photoreceptors that absorb the light energy needed to drive chemical reactions. They are organised into clusters called photosystems. Within a photosystem, most pigment molecules, such as chlorophyll b and carotenoids, act as antenna pigments, capturing light and funnelling the energy to a central molecule. This central molecule, chlorophyll a, is known as the reaction centre, where the conversion of light energy to chemical energy begins.
4. Why is chlorophyll a considered the primary photosynthetic pigment?
Chlorophyll a is called the primary or essential photosynthetic pigment because it is the only pigment that can directly participate in the light reactions of photosynthesis. It is at the reaction centre of the photosystems where it absorbs energy from other pigments and uses it to initiate the electron transport chain, directly converting light energy into chemical energy (ATP and NADPH). All other pigments are considered accessory because they must pass their absorbed energy to chlorophyll a.
5. How do accessory pigments like carotenoids benefit a plant?
Accessory pigments, such as carotenoids and xanthophylls, serve two crucial functions:
- Broadening the Absorption Spectrum: They capture wavelengths of light that chlorophylls cannot absorb efficiently, primarily in the blue-green range. This allows the plant to use a wider range of the light spectrum for photosynthesis.
- Photoprotection: They protect the chlorophyll molecules from photodamage. When light intensity is too high, carotenoids help to dissipate the excess light energy as heat, preventing the formation of harmful reactive oxygen species.
6. What biological process explains why leaves change colour in autumn?
The change in leaf colour in autumn is a result of the degradation of chlorophyll. As days become shorter and temperatures drop, plants reduce and eventually stop producing chlorophyll. The highly unstable chlorophyll molecule breaks down, and its dominant green colour fades. This unmasks the yellow and orange colours of the more stable carotenoids and xanthophylls that were present in the leaf all along. In some plants, cool temperatures and bright sunlight trigger the production of new red and purple pigments called anthocyanins.
7. What is the key difference between a plant pigment like chlorophyll and an animal pigment like haemoglobin?
The primary difference lies in their central metal ion and biological function. Both chlorophyll and haemoglobin are porphyrin compounds, but:
- Chlorophyll contains a magnesium (Mg) ion at its centre. Its function is to absorb light energy for photosynthesis in plants.
- Haemoglobin contains an iron (Fe) ion at its centre. Its function is to bind to and transport oxygen in the blood of animals.
8. What is the importance of biological pigments in living organisms beyond photosynthesis?
Biological pigments are vital for many processes besides photosynthesis. Their importance includes:
- Vision: The pigment rhodopsin in the retina of the eye detects light, enabling sight.
- Oxygen Transport: Haemoglobin (red) in blood and myoglobin in muscles transport oxygen.
- Protection & Camouflage: Melanin provides colour to skin, hair, and eyes, protecting against UV radiation and enabling camouflage.
- Pollinator Attraction: The vibrant colours of anthocyanins and carotenoids in flowers attract insects and birds, facilitating pollination.
