Question

Decomposers like fungi and bacteria are

(i) autotrophs
(ii) heterotrophs
(iii) saprotrophs
(iv) chemo-autotrophs

• A. (i) and (iii)
• B. (i) and (iv)
• C. (ii) and (iii)
• D. (ii) and (iv)

Answer 1

The correct option is C (ii) and (iii)

Decomposers are organisms like bacteria and fungi that feed on dead and decaying organic material (detritus) releasing nutrients back into the environment. They are heterotrophs because they are dependent on other sources for food and energy and cannot make their own food. Hence ii is correct.

They are also saprotrophs because they feed on dead and decaying organic matter. They secrete digestive juices or enzymes that break the complex organic matter stored in dead and waste material into simple inorganic substances like carbon dioxide, water and nutrients. They play a very important role in nutrient cycling in this way. So iii is correct.

Autotrophs are organisms that are able to synthesise their own food with the help of sunlight (photoautotrophs like green plants) or with the help of energy released from chemical reactions (chemo-autotrophs). Hence i and iv are incorrect.

For example, sulfur oxidizing bacteria is a chemo-autotroph, which plays a significant role in the transformation of hydrogen sulfide to sulphuric acid in the Earth.