Question

Classification of organism on energy and carbon utilization

Answer 1

Explanation:

Carbon and energy metabolism are intimately associated in all living organisms. On the basis of the ability of organisms to obtain carbon and energy from usable sources, they can be divided into several categories.

Considering the energy source first, organisms can be divided into two groups:

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1. The phototrophs and

2. The chemotrophs.

The phototrophic organisms are capable of utilizing radiant energy i.e. light as energy source by virtue of their ability of carrying out photosynthesis. The chemotrophic organisms, on the other hand, obtain energy from oxidation of chemical compounds.

Both types convert the usable energy source into a readily utilizable source, adenosine triphosphate (ATP). As described earlier, this compound acts as the “energy-currency” in most biological systems. Generation of ATP in photosynthesis is known as photophosphorylation and that of chemotrophs as substrate-level phosphorylation and oxidative phosphorylation.

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On the basis of carbon source utilizing ability, organism can also be divided into two broad groups the lithotrophs and the organotrophs. Lithotrophic organisms are able to use inorganic carbon source, mainly carbon dioxide (rarely carbon monoxide), while organotrophic ones depend mainly on organic compounds for supply of carbon. The lithotrophs are commonly known as autotrophs, and the organotrophs as heterotrophs. Both autotrophs and heterotrophs can be phototrophic or chemotrophic.

Answer 2

The living organisms can be classified according to the utilisation of carbon and how they use metabolism and energy source.

Based on Carbon utilisation various organisms are classified into Autotrophs and Heterotrophs.

• Autotrophs are organisms that convert inorganic compounds (carbon dioxide) into organic carbon compounds.

Example:- Plants and cyanobacteria 

• Heterotrophs are organisms that depend for nutrients on more complex organic carbon compounds.

Example:- Human and Escherichia coli

Based on energy utilisation from the source various organism are classified as Phototrophs and Chemotrophs.

• Phototrophs are organisms that acquire their energy for electron transfer from light.

Example:- Algae and Cyanobacteria

• Chemotrophs are organisms that collect energy for electron transfer by breaking chemical bonds.

Example :- Fungi and Protozoa

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