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 highly acidic environment with a pH below 3.

How many of the above statements are correct?

1. Only one
2. Only two
3. All three
4. None

Explanation

Statement 1 is correct

• Certain extremophiles called hyperthermophiles (e.g., archaea found near hydrothermal vents) can grow at temperatures exceeding 100°C under high-pressure conditions.

Statement 2 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. Psychrophiles are microorganisms that can grow at 0 °C and below, have an optimum growth temperature close to 15 °C.

Statement 3 is correct

• Acidophiles are organisms that can thrive in environments of high acidity, at a pH of 3.0 or below. Examples of acidophilic bacteria include Helicobacter pylori, Alicyclobacillus and Acetobacter acet. Acidophiles are found in highly acidic environments such as sulphuric pools, areas polluted by acid mine drainage, and even our own stomachs.

Answer: (c) All three; Difficulty Level: Easy