By comparing electron transport in cyanobacteria, green sulfur bacteria and purp
ID: 168733 • Letter: B
Question
By comparing electron transport in cyanobacteria, green sulfur bacteria and purple sulfur bacteria, what could be concluded about the evolution of photosynthesis? Multiple Choice Photosynthetic pathways are very different and arose independently. Photosynthetic pathways are very different and arose from a common ancestor. Photosynthetic pathways are similar and arose independently. Photosynthetic pathways are identical and all bacteria are very closely related. Photosynthetic pathways are similar and arose from a common ancestor.Explanation / Answer
Cyanobacteria are oxygenic phototrophic bacteria which contian chlorophyll, use lifht as a source and evolve oxygen To help them in photosynthesis they have highly organised membranous structures and have chlorophyll a. They prove their ecological and evolutionary succes, as they reduce nitrogen and carbon dioxide under aerobic conditions. They could also reduce sulphur in dark, thus sharing an ancestral property.
Purple sulphur bacteria (Chromatiaceae) are ananerobic anoxygenic phototrophic bacteria. They do not use water as the reducing agent, and hence do not use oxygen. They use hydrogen sulpihide to produce elemental sulphur, which acts as an electron donor to CO2 fixation.
Green sulphur bacteria (Chlorobiaceae) are also anaerobic anoxygenic phototrophic bacteria. Green-sulphur bacteria live as photolithotrophs, using H2S as the electron donor for CO2 fixation. Granules of elemental sulphur are deposited only outside the cells and the sulphur
Based on these facts, it could be concluded that photosynthetic pathways are different and arose from a common ancestor.
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