Question 41 from UPSC CSE 2023 - Environme nt

Question

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 environments with a pH below 3.
How many of the above statements are correct?

IASCODEX · Accepted Answer

Correct Option: C. All three

Strategy: Focus on the extremophilic nature of certain microorganisms to validate the statements.
*   **Statement 1:** Recall hyperthermophiles that thrive above 100°C.
*   **Statement 2:** Identify psychrophiles that survive and reproduce below 0°C.
*   **Statement 3:** Consider acidophiles that exist in very low pH conditions.
Recognizing the existence of these extremophiles confirms all three statements as correct.

Key Info: Extremophiles are microorganisms adapted to thrive in environments lethal to most life forms.

*   **Hyperthermophiles** grow optimally at very high temperatures, often exceeding 80°C. Some species, like *Pyrolobus fumarii* and *Pyrococcus furiosus*, thrive even above the boiling point of water (>100°C), typically in hydrothermal vents.
*   **Psychrophiles** survive and multiply at very low temperatures, including below the freezing point of water (0°C). These organisms are prevalent in polar environments, alpine regions, and glaciers; some can grow as low as -20°C.
*   **Acidophiles** thrive in highly acidic environments with pH values below 3. Such environments include acidic hot springs, mine drainage sites, and volcanic soils. Acidophilic bacteria (e.g., *Acidithiobacillus*) and archaea adapt cellular mechanisms to maintain internal pH stability.

The study of extremophiles is significant to biology, biotechnology, astrobiology, and environmental science. Their unique enzymes and adaptations offer clues to survival in harsh conditions and have industrial applications, such as PCR enzymes from *Thermus aquaticus* (an extreme thermophile).

IASCODEX · Answer

Option A: Only one

IASCODEX · Answer

Option B: Only two

IASCODEX · Answer

Option D: None