Question

Sulphur bacteria are examples of
A. Carnivores
B. Heterotrophs
C. Saprophytes
D. Autotrophs

Answer 1

Hint: Bacteria are microscopic organisms that are found abundantly in the environment. They are prokaryotic, that is their genetic material is not enclosed within a well defined membrane.

Complete answer:
Carnivores are the organisms that consume other organisms as their prey by hunting. Since, Sulphur bacteria are not concerned with hunting so cannot be a carnivore. Therefore, option B is an incorrect option.
Organisms depending on other beings for meeting food requirements are referred to as heterotrophs. They cannot prepare their own food and depend on autotrophs for nutritional requirements. Since, this is not a case with Sulphur bacteria, therefore, it cannot be a correct option.
Saprotrophs include organisms that depend on dead and decaying matter such as dead animals, plants, fallen leaves, excreta, other products of plant and animal origins, etc. Since, this is not a case with Sulphur bacteria, therefore, it cannot be a correct option.
Autotrophs are those organisms who prepare their own food with the help of organic and inorganic matter.
Organic matter such as - Carbon sources, Electron donors.
Inorganic matter like - Hydrogen sulphide.
Autotrophs are basically of two types:
1. Photoautotrophs - Organisms which use sunlight and possess chlorophyll pigment to entrap sunlight and use it to prepare food.
2. Chemoautotrophs - Organisms that use chemicals instead of sunlight to prepare their food are called Chemoautotrophs. The examples of chemoautotrophs are Hydrogen bacteria (Hydrogenomonas), Sulphur bacteria (Thiobacillus), Iron bacteria (Leptothrix).
Since Sulphur bacterias, prepare their own food, option D is the correct answer.

So, the correct answer is option D. Autotrophs.

Note:
Photolithotrophs are divided into two types of sulphur bacterias:
1. Purple Sulphur Bacteria
2. Green Sulphur Bacteria
Chemotrophs are classified into these groups-
1. Hydrogen Bacteria
2. Iron Bacteria
3. Sulphur Bacteria
4. Sulphur bacteria in both of these groups are autotrophs.