All living organisms need food. Animals obtain food from plants but plants prepare it for themselves by the process of photosynthesis.
Photosynthesis In Plants
Photosynthesis is an important activity of all green plants which are able to synthesize (make something) food from carbon dioxide and water in the presence of chlorophyll and light energy. The essential chemical steps in this process are the same in all green plants.
What Does Photosynthesis Produce?
- Food for all. Photosynthesis is ultimately the source of energy and food for all living beings. It is directly for plants and indirectly for animals and humans who eat the plants or the plant-eating animals.
- Oxygen to breathe in. Photosynthesis is the only biological process which releases oxygen into the atmosphere. The oxygen supports all life on the earth.
What is Photosynthesis – Definition
Photosynthesis, in a way, is the most significant life process – it provides food for all animal life including humans, and also the life-supporting free oxygen gas in the atmosphere for breathing.
|Photosynthesis is the process by which living plant cells, containing chlorophyll, produce food substances (glucose and starch), from carbon dioxide and water, by using light energy. Plants release oxygen as a waste product during this process.|
What Does Photosynthesis Mean? – (Photosynthesis Meaning)
We can split the complete word into two “Photo” and “Synthesis”. It means photo ( which means ” light”) and synthesis (which means “to put together”). -OR- It also means synthesis compound with the help of radiant energy.
The photosynthesis process starts due to its most important pigment named chlorophyll. Splitting complete word into two. Chloro and phyll.
- Chloro – Green,
- Phyll : leaf
Chlorophyll is the green colouring matter found in plants. It is contained in chloroplasts. Ordinarily, there may be 40-50 chloroplasts in a cell. Chloroplasts are minute oval bodies bounded by a double membrane, and their interior contains closely packed flattened sacs (thylakoids) arranged in piles (grana) lying in a colourless ground substance called stroma. (See Diagram)
The pigment chlorophyll is contained in the walls of thylakoids. Chloroplasts are mainly contained in the mesophyll cells. These are found in the guard cells of the stomata and in the outer layer of young green stems.
What are the Reactants of Photosynthesis?
Leafs of the plant contains the Mesophyll cells (both palisade and spongy). These are the principal centers of this activity.
Steps of Photosynthesis
- Chlorophyll – During daytime, when sunlight falls on the leaf, the light energy is trapped by the chlorophyll of the upper layers of mesophyll, especially the palisade cells. This energy is utilized in chemical processes involved in the manufacture of food, where the raw materials used are carbon dioxide and water.
- Carbon dioxide – Carbon dioxide from the atmosphere enters the leaf by diffusion (exchange of gases) down a concentration gradient (higher concentration outside the leaf, and less concentration inside) through the stomata.
- Water from the soil is taken up by the roots, sent up through the stem. Finally to the leaves where it is distributed in the mesophyll tissue.
- Light Reaction.( to be updated on 20 Jan 2018)
- Dark Reaction.( to be updated on 25 Jan 2018)
Word Equation For Photosynthesis (Reaction)
The overall reaction is as follows –
Carbon Dioxide + Sunlight + Water → Glucose (Sugar) + Oxygen
During the process, Chlorophyll is highly sensitive to light. So, excessive light may destroy it. However, the formation of chlorophyll itself depends on the exposure of the plant to light.
|You will be surprised to know that there are nine types of chlorophyll. Two out of these, chlorophyll-A and chlorophyll-b, are best known and most abundant.|
Balanced Chemical Equation For Photosynthesis
The summary chemical equation of this process is as follows –
6 CO2 + 12 H2O → C6 H12 O6 + 6 H2O + 6 O2
The glucose molecule C6H12O6 is a simple sugar readily soluble in water.
The 6 molecules of H2O liberated at the end of the process are those that are re-formed during a chain of reactions and not out of the original ones.
Products of Photosynthesis
There are three end-products. 1. Glucose (C6 H12 O6) 2. Water 3.Oxygen.
Glucose: The simple sugar glucose is used in four different ways as required by the plant.
- Immediately consumed by the plant cells.
- Stored in the form of insoluble starch.
- Converted into sucrose.
- Used in synthesizing fats, proteins, etc.
Water: The water produced in the process may be re-utilized in the continuance of photosynthesis.
Oxygen: Some of the oxygen may be used in respiration in the leaf cells (the phenomenon is called photorespiration), but the major portion of it is not required and it diffuses out into the atmosphere through the stomata.
In a sense, even this oxygen is not a waste, because all organisms require it for their existence including the plants which require it at night.
This is all about the basics of What is Photosynthesis?Meaning- In Plants-Process Steps-[Reactant ,Equation,Products of Photosynthesis]