Question

Which of the following are found in extreme saline conditions?
A. Mycobacteria
B. Archaebacteria
C. Eubacteria
D. cyanobacteria

Answer 1

Hint:First of all to be clear saline conditions refers to the salty conditions. For example salty lakes, salt marshes or brines, etc. Based on the diverse living conditions and metabolic activities bacteria are divided into different groups.

Complete answer:
Archaebacteria are the unique type of bacteria that is generally found in extreme environmental conditions. It is further divided into three groups
Halophiles: They are the group that consists of anaerobic bacteria and love saline conditions. They generally occur in deep- sea vents where the temperature is very high i.e. above 100 degree celsius under which the water remains into liquid form only. Halophiles have a purple colour pigmented membrane that is made up of bacteriorhodopsin which is primarily present to harness the sun's energy. They carry different types of photosynthesis in which carbon dioxide is not converted into sugar form and the harnessed light energy is utilized to carry forward formation of ATP by process of chemiosmosis. Examples are halobacterium, and halococcus.
Thermoacidophiles: they are found at very high temperatures, hot as well as acidic. Examples are thermoplasma and sulfolobus.
Methanogens: they are found in marsh,swamp areas. They help in fermentation of cellulose. Therefore, they are found in the rumen of herbivorous animals.

Hence, the correct option is option B i.e. archaebacteria.

Note:- Archaebacteria are known as the oldest of the living fossils. They represent the oldest form of life and have survived all geological changes on earth from the beginning of the time. They are anaerobes and developed methods of oxidizing chemical substances with the help of oxygen.