March 4, 2014

10th New Syllabus Biology - Autotrophic Nutrition

Autotrophic Nutrition: We know that autotrophs are the organisms capable of using light energy to synthesize chemical compounds. They acquire nutrients like some minerals and water from the soil as well as some gases from the air. They are capable of producing large compounds like carbohydrates, proteins, lipids etc. from these very simple substances. These carbohydrates produced by plants are utilized for providing energy in most living organisms and all animals including human beings.

Everything we eat comes from plants why don’t the plants get used up? What are they using to grow and produce more plants, more seeds?
Scientists have been working for centuries to find out how plants carry out their life processes. We know that among all life processes, the process of photosynthesis makes plants the universal food provider for all living organisms.

You had studied somthing about photosynthesis in your earlier classes. Van helmant and other scientiests believed that platns gets food material not only from soil other factors are also there. What do you think are some raw materials needed for photosynthesis?

What could be the end products of the process of photosynthesis? Let us study the process of photosynthesis in detail to find out more about this.


Photosynthesis is the process by which all green plants contains the green pigment called chlorophyll, which build up complex organic molecules from relatively simple inorganic ones using light as an energy source. The process is very complex and there are several steps as well as intermediary compounds that are formed. Scientists had tried to formulate a simple equation for photosynthesis over the past 200 years. An equation that was readily accepted and is still widely used is the one formulated and proposed by C.B. Van Neil in the year 1931 which is as follows. His opinion was, “for each molecule of carbohydrate formed, one molecule of water and one molecule oxygen is
also produced”. This is a very simplified equation and does not reflect the complexity of the process of photosynthesis yet we shall use it for now. What would be the reaction to show that glucose (C6H12O6) is being synthesized?

Write down a balanced equation to show this. It is known that plants synthesize carbohydrates, the smaller simpler ones first and from which the more complex ones like starch and cellulose are synthesized. Plants are also capable of synthesizing all other compounds like proteins, fats etc.

Animals are not capable of synthesizing carbohydrates and they have to depend on plants for the same. Can we state that photosynthesis is the basic energy source for most of the living world? Why, why not? Let us find out whether plants produce carbohydrates by the process of photosynthesis.

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