The process of Photosynthesis
Photosynthesis is the process of capturing light energy and transforming it into chemical energy. Green plants and several other organisms use light energy and convert carbon dioxide and water into glucose. In this process, oxygen is produced as a by-product. This process can be seen in green plants and photosynthetic bacteria. They use electromagnetic radiation and convert it into chemical energy. With the help of water and sunlight, they absorb carbon dioxide from the atmosphere and turn it into oxygen and carbohydrates.
The process provides not only energy needed but also helps in forming biomolecules. This reaction is an oxidation-reduction reaction that uses sunlight and nitrogen available in the atmosphere. It is the basic element in the food cycle. All the other organisms derive their energy from green plants and other photosynthetic bacteria. Hence, these plants are called autotrophs as they prepare their own food with the help of naturally available elements. One of the essential requirements for this process is a pigment called “chlorophyll”. This pigment is present in green plants and some bacteria. It helps in tapping sunlight and starting the entire process.
This process of converting light energy to other forms differs in plants and other bacteria. In the case of plants, water is used to form energy in the form of glucose and oxygen. On the other hand, in the case of bacteria, hydrogen sulphide replaces the water along with carbon dioxide to release carbohydrates, sulfur, and water molecules. Some of the photosynthetic pigments are chlorophyll, phycobilins, bacteriorhodopsin, carotenoids. Chlorophyll is present in most green plants and helps in receiving sunlight and converting it into energy and glucose. They have single and double bonds alternatively, this makes them effective photoreceptors. Bacteriorhodopsin is another photosynthetic pigment that is generally present in Halobacteria. Phycobilins are present in cyanobacteria and red algae.
The photosynthesis process step by step conducts these reactions and maintains the balance of oxygen and carbon dioxide in the atmosphere. However, photosynthesis in plant leaves usually occurs in two ways. These are light-dependent reactions and light-independent reactions or dark reactions.
Light-Dependant Reaction
This process happens in the thylakoid membrane and needs a constant supply of photons or light energy. Chlorophylls use this energy and produce ATP and NADPH. Water molecules are transformed into oxygen through this process.
Light-Independent Reaction
This reaction happens in the stroma and can take place in the absence of light. It takes up ATP and NADPH produced from the light reaction to break down carbon dioxide. This process helps in forming three types of carbon sugars that create glucose.
Let’s understand the photosynthesis process step by step!
Step by Step Procedure of Photosynthesis
Fig: Process of photosynthesis
Plant leaves absorb the photons from sunlight that excite chlorophyll and activate electrons. In the first step, the water absorbed by plant roots is split into oxygen and hydrogen ions.
Then the excited electrons from ATP and NADPH. This process happens through the electron chain. Likewise, in this process, oxygen is released into the atmosphere through leaves.
In the next step, the energy from the light reaction transforms carbon dioxide into glucose. This whole process takes place in several stages. The series of reactions start with 3-Ribulose biphosphate (RuBP) and ends with the same molecule forming glucose.
The Rubisco enzyme is an essential component of this Calvin Cycle that initiates all the reactions.
All the significant reactions of the photosynthesis process generally take place during the daytime in the chloroplasts of leaves.
Following is the fundamental equation of photosynthesis
6CO2 + 6H2O (+ light energy) → C6H12O6 + 6O2
This is the overall overview of how the photosynthesis process step by step takes place.
Factors that Affect Photosynthesis
Following is the list of factors that influence the rate of photosynthesis.
Temperature and Light Intensity
Generally, with higher light and temperature intensity, the rate of photosynthesis increases. However, after a specific intensity of light, this rate saturates. It solely depends on the growing condition and species of the plants.
Water
The rate of photosynthesis depends on a steady water supply. A minimal amount of water is required to conduct the reactions. The maximum amount of water transpires through the stomata of leaves.
In arid areas, therefore, the opening and closing of stomata are limited. This allows reserving the water supply and overall temperature of leaves.
Carbon Dioxide
The concentration of carbon dioxide influences mainly the dark reactions of photosynthesis. Hence, this rate increases with the increased supply of carbon dioxide.
Minerals
A few minerals like potassium, iron, magnesium, phosphate, etc. are essential for plant growth. They also hasten the rate of photosynthesis of plants.
Apart from that, a few other factors like environment, species, etc. affect the rate of photosynthesis.
Importance of Photosynthesis
Introduce energy and fixed carbon into the ecosystem.
Reduce a large quantity of carbon dioxide from the atmosphere.
Produces oxygen that sustains all life.
Photosynthesis happens in the autotrophs, so they indirectly introduce energy into the ecosystem and that energy travels to other trophic levels
It is very important also for the heterotrophs which are dependent on autotrophs for energy.
It helps to maintain a healthy relationship between animals, plants, and humans making them mutually dependent.
Sunlight becomes the primary source of energy in the world and facilitates photosynthesis.
Pop Quiz
Photosynthesis is a/an _______________ process.
_______________ colour of light is responsible for photosynthesis in bacteria.
Which metal is present in both chlorophyll “a” and “b”?
Magnesium
Iron
Manganese
Copper
Chlorophyll is the structural unit of photosynthesis. True/False.
Answers: 1- Anabolic, 2-Red, 3-a), 4- False.
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FAQs on Photosynthesis Process
1. What is the Process of Photosynthesis in Plants?
Photosynthesis is the process using which green plants and some other organisms convert light energy into chemical energy. It is a chemical process that happens in plants in general and some kinds of microorganisms. It absorbs sunlight and electromagnetic energy from the surroundings and converts them into chemical energy. This chemical energy produced from photosynthesis is stored in plants on the roots, fruits, etc. Humans and other animals consume these stored materials and finish the loop of the food chain.
This process is the base of the entire food chain. The energy produced here is transferred to the trophic levels above. At the basic level, photosynthesis takes place in the cell organelles known as chloroplasts. It has a pigment called chlorophyll, which gives green colour to the leaves.
2. What Does Photosynthesis Produce?
During photosynthesis, green plants capture light energy and use it in converting carbon dioxide and water into glucose and oxygen. It is a chemical process that generally takes place in plants and sometimes in a few microorganisms like cyanobacteria, red algae. This process uses the natural elements available in the surroundings like sunlight, water, and carbon dioxide to produce carbohydrates, oxygen, and glucose. This glucose and carbohydrates are stored in different parts of the plants like roots, fruits, etc. Some of the stored carbohydrates are used by the plants to live and grow. The excess energy is converted to storage and they are consumed by other organisms. Heterotrophs consume food from green plants.
3. Why is Photosynthesis Important?
The most crucial aspect of photosynthesis is that it is the primary source of oxygen and food that makes life possible on the earth. The food produced and stored in the plants is the foundation of the food chain of an ecosystem.
4. What happens when photosynthesis does not occur?
Photosynthesis is a process that converts light and electromagnetic energy into chemical energy. It is the basic reaction on which the entire world depends. Autotrophs generally perform the photosynthesis process. They are the living organisms that make their own food with the natural elements surrounding them. For example, plants and certain microorganisms perform photosynthesis. This further leads to the energy transfer in the next trophic levels. Heterotrophs depend upon autotrophs to meet their energy needs. So if the process of photosynthesis does not take place, the energy cycle will break. Plants can produce any glucose neither for themselves nor for others. We can live only for some days with already existing food and resources. So it is very important to protect all the natural elements involved in this process of photosynthesis.
5. What is the role played by chlorophyll in photosynthesis?
Chlorophyll is a pigment present in green plants in the chloroplast. They help in converting light energy to chemical energy and glucose. Chlorophyll uses carbon dioxide, water, and light energy to make carbohydrates. This pigment is present in green plants, cyanobacteria, and some algae. It has magnesium ions closed in a large ring made up of chlorine. Apart from this pigment, many other elements like water, rhizobium bacteria help in the process of photosynthesis. For example, the rhizobium bacteria helps in photosynthetic activity by growing in anaerobic conditions and facilitating the process. It helps in fixing nitrogen from the atmosphere. This will avoid the usage of artificial and synthetic chemical fertilizers and improve soil fertility naturally.
