Question 1

Which of the following is a micro-organism?

Accepted Answer

A fungus is a type of micro-organism. Micro-organisms are tiny organisms that cannot be seen with the naked eye and include bacteria, fungi, protozoa, and some algae.

Question 2

The process of conversion of sugar into alcohol is known as:

Accepted Answer

Fermentation is the process in which yeast converts sugar into alcohol and carbon dioxide. Louis Pasteur discovered fermentation in 1857.

Question 3

Which bacterium helps in the setting of curd?

Accepted Answer

Lactobacillus is the bacterium that promotes the formation of curd. It multiplies in milk and converts it into curd.

Question 4

Blue-green algae fix which gas to enhance soil fertility?

Accepted Answer

Blue-green algae (cyanobacteria) fix atmospheric nitrogen directly from the air to enhance soil fertility and enrich it with nutrients.

Question 5

Who discovered the vaccine for smallpox?

Accepted Answer

Edward Jenner discovered the vaccine for smallpox in 1798. Vaccination helps the body develop immunity against specific diseases.

Microorganisms: Friend and Foe — NCERT Class 8 Science Important Questions & Revision Notes