Consider the following statements:

1. Some microorganisms can grow in environments with temperature above the boiling point of water.

2. Some microorganisms can grow in environments with temperature below the freezing point of water.

3. Some microorganisms can grow in a highly acidic environment with a pH below 3.

How many of the above statements are correct?

(a) Only one

(b) Only two

(c) All three

(d) None

 8. Ans: c

Explanation:

Thermophilic microorganisms have the capacity to grow at elevated temperatures sometimes exceeding the boiling point of water. The record is presently held by a hyperthermophilic Archaea, close to Pyrodictium occultum, known as strain 121 that still grows at 121 °C. 

Hence Statement 1 is correct.

The microorganisms live in every part of the biosphere, and some of them are even capable of growing at low temperatures, including those below the freezing point. Most of the microorganisms are well able to grow down to 0°-2°C. 

Hence Statement 2 is correct.

Acidophiles are microorganisms that show optimal growth in highly acidic environments. These are of two types. The extreme acidophiles dwell in environments with a pH value <3, and moderate acidophiles grow optimally in conditions having pH values ranging between 3 and 5.

Hence Statement 3 is correct.

Read: Previous Year UPSC Environment Questions (PYQs) With Explanation 2023