Describe the process of photosynthesis in green plant
Answers
Answer: Photosynthesis, the process by which green plants and certain other organisms transform light energy into chemical energy. During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds.Photosynthesis is critical for the existence of the vast majority of life on Earth. It is the way in which virtually all energy in the biosphere becomes available to living things. As primary producers, photosynthetic organisms form the base of Earth’s food webs and are consumed directly or indirectly by all higher life-forms. Additionally, almost all the oxygen in the atmosphere is due to the process of photosynthesis.
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- PHOTOSYNTHESIS :-
=》 Photosynthesis defined as the conversion of light energy or radiant energy into chemical energy by the green parts of plants.
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The process of photosynthesis occur only in green plants because this process requires present of green coloured pigment called chlorophyll.
- PHOTOSYNTHETIC PIGMENTS :-
=》 Photosynthetic pigments are the coloured organic substances present in the plants which can absorb the visible part of Sunlight. They are present in the special plastids of plant cell known as chloroplast.
These pigments can absorb the different of wavelength of light containing the light energy which is used in process of photosynthesis. Hence, such pigments are referred as photosynthetic pigments.
Light reaction or photochemical phace consists of light, driven splitting of water or photolysis, evolution of Oxygen and formation of assimilatory power like NADPH2. It occurs in granum thylakoit of chloroplasts.
- PHOTOPHOSPHORYLATION :-
=》 Electrons are transferred into an electron transport chain which result in a formation of ATP from ADP and inorganic phosphate with the help of light energy.
The electrons ultimately reach and ADP+ and combined with 2H+ to form NADPH2.
- DARK REACTION :-
=》 The assimilatory power generated in the light reaction of photosynthesis is used up in the next step where carbon dioxide of atmosphere is utilised in the production of carbohydrate. This is step is discovered by Calvin, Benson, and Bassam in 1953.
It is a cyclic process which occurs in the stoma part of chloroplasts, that is totally enzymatic process and has been termed as dark reaction of photosynthesis.
The biochemical reactions occurring one after the other in the form of the cycle which utilise assimilatory power of light reaction and convert carbon dioxide into carbohydrate glucose ( C6H12O6 ) is called dark reaction or Calvin cycle.
The glucose synthesized by the process of photosynthesis, is a water soluble hexose monosaccharide carbohydrate. The excess glucose molecules which are not used up immediately are stored in the form of its starch with serves the reserve food material and utilised whenwere required by the plants.
- FACTORS AFFECTING PHOTOSYNTHESIS :-
=》 the rate of photosynthesis process is affected by several external and internal factors, these factors are :
- Light or sunlight : The ultimate source of light for photosynthesis in green plants is solar radiations. Out of total solar energy energy reaching to the Earth only a few small portion about 2% is used in photosynthesis under low light intensity the rate of photosynthesis is low and vice versa. Quality of light also affects photosynthesis green pigment chlorophyll absorb mostly the blue and red spectrum. They reflect green light.
- Temperature : the rate of photosynthesis increases by increasing temperature up to 40 degree Celsius.Above this temperature, there is a decrease in photosynthesis similarly low temperature also inhabits photosynthesis low temperature lower the activity of enzymes and high temperature causes inactivation of enzymes.
- Carbon dioxide : It is present in the atmosphere in the concentration of 0.033 percent by volume. The rate of photosynthesis increased by increasing the concentration of carbon dioxide in the atmosphere. If the light and temperature conditions are not limiting. At the same time, very high concentration of carbon dioxide becomes toxic for plants and inhabits photosynthesis.
- Water : It is rarely act as a limiting factor because less than 1% of the water absorbed by the plant is used in photosynthesis. However, the rate of photosynthesis is is lowered if the plants are inadequately supplied with water.