CAPF AC 2022 Q8: Science & Technology – Biology
The organisms that prefer high salt concentration habitats refer to as
- (a) alkaliphiles
- (b) calcifuges
- (c) halophiles
- (d) nitrophiles
Answer: (c) halophiles
Explanation
Organisms that love salt
How to think: break the word.
Halo means salt (as in halite, rock salt).
Phile means lover.
So a halophile is a salt lover.
| Term | Meaning |
|---|---|
| Halophiles | Thrive in high salt habitats |
| Alkaliphiles | Thrive in alkaline (high pH) habitats |
| Calcifuges | Plants that avoid lime-rich (calcium) soils |
| Nitrophiles | Plants that prefer nitrogen-rich soils |
| Thermophiles | Thrive in very hot places |
| Acidophiles | Thrive in acidic places |
Examples: salt-loving archaebacteria live in salt pans and the Dead Sea.
Plants of salty soils, such as mangroves, are called halophytes.
Answer: (c) halophiles.
Why each option is right or wrong
- (a) Incorrect. Alkaliphiles prefer alkaline conditions, not salt as such.
- (b) Incorrect. Calcifuges are plants that avoid calcium-rich soils.
- (c) CORRECT. Halophiles prefer habitats with high salt concentration.
- (d) Incorrect. Nitrophiles prefer soils rich in nitrogen.
Key point
Extremophiles: halophiles (salt), thermophiles (heat), psychrophiles (cold), acidophiles (acid), alkaliphiles (alkali). Archaebacteria include halophiles, thermoacidophiles and methanogens. Halophytes are salt-tolerant plants such as mangroves.
Remember
Halo = salt, phile = lover.
Common mistakes
- Mixing up halophiles (salt) with alkaliphiles (high pH).
- Confusing halophiles (microbes) with halophytes (salt-tolerant plants).
- Reading calcifuge as calcium lover; fuge means to flee.
Exam tip
Educated guess: halogen means salt former, and halite is rock salt. The root halo always points to salt.
Sources
- NCERT Class XI Biology — Biological Classification (Archaebacteria: halophiles)
- NCERT Class XII Biology — Organisms and Populations (adaptations)