Evolution of photosynthesis and aerobic respiration, Biology

Evolution of Photosynthesis and Aerobic Respiration

It is assumed that the earlier form of the bacteria utilised H2S for the preparation of food. The following reaction shows this process:

CO2 + H2S Light energy Sugar = (CH2O)n + Sulphur (S)
                 Bacteriochlorophyll


Since this reaction takes place in the presence of sunlight, it is called as photosynthesis. In this type of photosynthesis H,S is used.

Later, a more efficient photosynthetic system evolved in which H,O instead of H, S was used as an electron donor. This led to the release of free oxygen (0,). This is the usual form of photosynthesis with which you are familiar.

CO2 + H2O + Solar energy Sugar = (CH2O)n + 02
                     (Chlorophyll )

The photosynthesis which takes place by utilising water, helped in the evolution of autotrophic mode of nutrition and release of free oxygen in the atmosphere. The release of free oxygen made possible a far more efficient method of getting energy from glucose by respiration. The free oxygen got converted into ozone (03) in the presence of ultraviolet radiation and formed an ozone layer in the upper atmosphere. The formation of this layer prevented the incoming ultraviole rays which otherwise could have broken down the proteins, nucleic acids etc. Thus, the formation of ozone layer made existence of various
forms of life on earth possible.

The free 02 generated by photosynthesis was perhaps more like a poison to anaerobic bacteria initially. But some bacteria soon developed a metabolic system in which oxygen was used for the oxidation of food (respiration). This was a much more efficient system for the release of energy from organic molecules, compared with the earlier system of respiration, that is glycolysis. Some of these aerobic bacteria lost the ability of H2S photosynthesis and became perhaps the ancestor of another class cf organisms, that used the mitochondria for respiration. In mitochondria, the energy released by respiration is stored in
the form of ATP molecules for further use.

Posted Date: 12/9/2012 11:41:08 PM | Location : United States







Related Discussions:- Evolution of photosynthesis and aerobic respiration, Assignment Help, Ask Question on Evolution of photosynthesis and aerobic respiration, Get Answer, Expert's Help, Evolution of photosynthesis and aerobic respiration Discussions

Write discussion on Evolution of photosynthesis and aerobic respiration
Your posts are moderated
Related Questions
Define Criteria for Assessment of Vitamin K Status? The parameters of blood clotting time and prothrombin time are used as criteria  to assess vitamin K status as this vitamin

Phylum Chordata- Chordata name given by Balfour. Herst put hemichordata into separate phylum. Lamarck gave the word tunicata & vertebrata. Pisces classified by Rom

Q. Concerning the nitrogen- containing bases that participate in nucleotides, what is the difference between RNA and DNA? In DNA nucleotides can be formed of thymine (T), adeni

Antiparkinsmian Drugs: Antiparkinsonian drugs are  the  specific drugs  to treat the extrapynnidal side effects  of  antipsychotic agents.  Anticholinergic drugs  block

What are the extraembryonic membranes present in vertebrates? The extraembryonic membranes that might be present in vertebrates are the yolk sac, the amnion, the chorion, the

What do you understand by term - acanthus The egg and larval phase of an acanthocephalan which passes from the female parasite to the feces of host.

Give a short explanation of what UPS really means and why it is so important to health practitioners and consumers/patients.

What do you mean by Acute Pericarditis? Ans. Acute pericarditis is defined as acute inflammation of the pericardium and is clinically characterized by chest pain, fever, t

Light - Marine Ecosystems Light is a limiting factor in the ocean as it contributes significantly to organic production and distribution of marine life. The ocean is divisible

Determine the types of blood There are three types of blood cells. They are Red Blood Corpuscles (RBC), White Blood Corpuscles (WBC) or leucocytes and blood platelets or thromb