All You Need to Know About Photosynthesis
Photosynthesis is the process by which a plant produces its food by converting light energy into chemical energy. Plants use water, carbon dioxide and sunlight in the presence of chlorophyll to produce their food or energy in the form of sugar and release oxygen as the byproduct. Understanding the process of photosynthesis means a clear concept about the different cellular and chemical activities going on in the plant body. The word photosynthesis is coined from the Greek word for meaning light along with synthesis. This implies a synthesis i.e a chemical reaction using light energy. This is not always for green plants only but certain bacteria and prokaryotes also use this process to prepare their food. In green plants or algae, the synthesis takes place within an important organelle called chloroplast where the pigment chlorophyll is present. Chlorophyll occurs in their leaves, stems, flowers, sepals and even in plastids.
Factors Affecting Photosynthesis
Various factors influence/affect the photosynthesis process. These are:
Light Intensity: More the light, the more will be the rate of photosynthesis. Similarly, low light will lead to a low rate of photosynthesis.
The Concentration of CO2: A higher CO2 concentration rate in a plant also accelerates the photosynthesis process. The required amount of CO2 is 300-400 PPM.
Temperature: If the temperature is between the range of 25 to 35 degrees Celsius, photosynthesis takes place effectively.
Water: An essential amount of water is required for stomatal opening, and it’s a key factor in the process of photosynthesis.
Pollution: The increasing rate of polluting particles in the atmosphere block the pores of somatic cells, and the intake of carbon dioxide becomes difficult.
Photosynthesis Equation
Carbon dioxide and water are the two major factors involved in the photosynthesis reaction. It’s an endothermic reaction, and the products resulting from it are oxygen and glucose. The formula is:
\[6CO_{2} + 6H_{2}O = C_{6}H_{1}2O_{6} + 6O_{2}\]
However, some bacteria don’t produce oxygen as a by-product of photosynthesis. They are called anoxygenic photosynthetic bacteria, and those who do it are called oxygenic photosynthetic bacteria.
Photosynthetic Pigments
Four types of photosynthetic pigments are present in the leaves of the plants. They are:
Chlorophyll a
Chlorophyll b
Xanthophylls
Carotenoids
Structure of Chlorophyll
Chlorophyll is a green colour pigment found in plants that play a vital role in photosynthesis. It allows the plants to absorb the energy coming from the sunlight, which is essential for photosynthesis.
Process of Photosynthesis
The photosynthesis process occurs in plants. It takes place in chloroplasts at the cellular level that contains chlorophyll. Leaves have parts called the petiole, epidermis, and lamina that absorb sunlight.
Photosynthesis Steps:
The photosynthesis process takes place at two levels or steps. These are:
Light Reaction of Photosynthesis (or) Light-dependent Reaction
The process begins in the daylight, by gathering the light. The two types of photosystems convert light energy into ATP and NADPH. During their conversion, oxygen is produced, and water is used. The equation of this step is:
\[2H_{2}O + 2NADP + 3ADP + 3P_{i} = O_{2} + 2 NADPH + 3ATP\]
The Dark Reaction of Photosynthesis (or) Light-independent Reaction
This is also called carbon-fixing. It is not dependent on light and takes place in chloroplast where the products from the earlier step are used. Plants intake CO2 and the Calvin Photosynthesis Cycle begins, where the six molecules of CO2 are converted into sugar or glucose.
\[3CO_{2} + 6NADPH + 5H_{2}O + 9ATP = G3P + 2H + 6NADP + 9ADP + 8P_{i}\]
Importance of Photosynthesis
The photosynthesis process is very important for the survival of living beings, and to continue the food chain. It also produces oxygen, which is required for breathing.
FAQs on Photosynthesis
1. What is photosynthesis?
The process by plants, of producing nutrients essential for survival.
2. What happens in a photosynthesis process?
The nutrients and glucose required for plants, and oxygen required for the animals, is created during the process.
3. What is the photosynthesis reaction?
A reaction taking place in plants that results in the production of glucose and oxygen.
4. What is shown in a photosynthesis diagram?
The photosynthesis diagram shows how the plants take sunlight and use it to produce essential nutrients and oxygen.
5. Why is photosynthesis in plants important?
It helps in the survival of the plants, the creation of products essential for the survival of living beings, and also to maintain the environmental balance.
6. How long is the photosynthesis cycle?
The whole process of photosynthesis, right from absorbing the light up to the final stage, takes place in just 30 seconds!
7. What is included in the mechanism of photosynthesis?
The mechanism of photosynthesis is an oxidation (oxygen releasing) and reduction reaction. It produces glucose along with oxygen.
8. What are the two phases of photosynthesis?
Photosynthesis is a synthesis reaction in which solar energy gets converted to chemical energy. However, the few steps involved in the synthesis also occur without light and based on that there are two phases of photosynthesis. The light-dependent reactions and the light-independent phase. In the light-dependent phase which is the starting phase the molecule of chlorophyll pigment absorbs one photon from the sun rays and loses electrons and ultimately after several steps generate NADPH and ATP which are used in the second phase or the light-independent phase of the reaction. In the dark phase, the atmospheric carbon dioxide is captured by a photosynthetic enzyme that uses the NADPH formed in the first phase to produce 3 carbon sugars which ultimately gets converted to starch and sucrose. Thus the two phases occur subsequently to form the end products which are the food of the plant.
9. What is the efficiency of the photosynthetic reaction?
Photosynthesis is the most important reaction or synthesis for which lives and the planet can run. It converts light to chemical energy. The efficiency of the reaction is however only 3-6% and the absorbed light cannot be used. The unused light gets dissipated to the atmosphere as heat. The efficiency of the synthesis varies with temperature, light intensity and proportion of carbon dioxide in nature which can vary the efficiency to a maximum of 8% even. The efficiency of the two phases can be separately taken into count and they both separately contribute to the total efficiency of the process.
10. Which factors can affect the process of photosynthesis?
Photosynthesis is affected by many factors including the corollary ones. The main factors that affect the process are as follows:
Light: Its intensity and wavelength
Carbon dioxide: Its concentration in the atmosphere
Temperature: Favorable temperature is needed
Water: Suitable quantity of water is needed
Apart from these factors photosynthesis also depends upon the factor referred to as the corollary factor which is the surface area of the leaf available to absorb the sunlight. This is why if a plant is overshadowed by other big trees it cannot efficiently photosynthesize.
11. What are the actual stages of the process of photosynthesis?
The process of photosynthesis can be divided into four essential steps. They are as follows:
Transfer of solar energy in thylakoid membranes of chlorophyll.
Transfer of the electrons in the light reaction
The synthesis of electron transport chain and ATP in the thylakoid membrane.
Absorption and fixation of carbon dioxide from the atmosphere with the formation of resulting stable plant food.
Each of these steps takes a specific time to happen with the maximum time of one second taken by the last step.
12. How is photosynthesis essential for the ecosystem?
Photosynthesis is the procedure by which plants convert solar energy into chemical energy in the form of their food. Photosynthesis is an ideal process for a living organism that has not evolved the capacity to actively move around in order to obtain food. Photosynthesis is also important for the consumers of the food web and thus is the starting point of all food chains of the ecosystem. Photosynthesis is thus an essential living process for plants and the ecosystem. All life on the earth depends upon photosynthesis, not only for the food but also for the oxygen in the atmosphere which is essential for them to respire. It is the process of photosynthesis that purifies the atmosphere by removing carbon dioxide from the environment and converting it to oxygen.
