Question

Autotrophic organism include
A. Green plants and sulphur bacteria
B. Green plant and all the bacteria
C. Bacteria and virus
D. Bacteria and fungi

Answer 1

Hint: The organisms which can synthesize their own food are called autotrophic organisms and those which cannot synthesize their own and derive their food from other organisms are called heterotrophic organisms.

Complete answer:
Food is essential for the survival of an individual. This food can be either synthesized on its own or can be taken from other organisms. Depending on the source of food, organisms are classified as autotrophic and heterotrophic. Autotrophic organisms synthesize their own food whereas heterotrophic organisms derive their food from other sources. The food obtained provides the organism with energy and nutrients which are essential for the growth and development of the organism.
Plants are the photosynthetic autotrophs and purple and green sulphur bacteria are chemosynthetic autotrophs. They use their derived energy to synthesize ATP and then use the ATP for the production of food.
Plants capture light energy and convert it into chemical energy by synthesizing high energy chemical bonds like ATP. ATP synthesized helps the plant to synthesize glucose by using the calvin cycle.
Chemosynthetic autotrophic bacteria are mostly present in soil and they perform oxidation of various inorganic substances like nitrates, nitrites, and ammonia, and then the energy released from this is used for their ATP production. Chemosynthetic autotrophic bacteria have an important role to play in the biological nutrient cycle like the nitrogen cycle. They also play a great role in recycling nutrients like nitrogen, phosphorus, iron, and sulphur.
In the nitrogen cycle, these bacteria perform nitrification that is the production of nitrate from ammonia. Bacteria like Nitrosomonas, Nitrococcus, and Nitrobacter take part in the process of nitrification, thus in the nitrogen cycle. Firstly ammonia is converted to nitrite by Nitrosomonas and Nitrococcus and then the nitrite formed is converted to nitrate by Nitrobacter bacteria. Not only plants and chemosynthetic autotrophic plants are autotrophic, even bacteria like cyanobacteria, also called blue-green algae, perform photosynthesis and synthesize their own food.
Hence, the correct answer is option A.

Note: The bacteria which do not synthesize their own food are called heterotrophic bacteria. Most of them are decomposers and play an important role in human life, such as in the production of antibiotics, curd, etc. Not all plants depend only on photosynthesis for food, some of them such as pitcher plants are insectivorous plants that are carnivorous when they are deprived of sunlight.