Q.38 Identify the correct pairs:
(i) Thermophile                      (a) grows optimal at 37 °C
(ii) Mesophile                         (b) grows optimal at low temperature
(iii) Psychrophile                   (c) grows optimal at high saline conditions
(iv) Halophile                         (d) grows optimal at 67 °C
(A) (i)–(d)
(B) (ii)–(b)
(C) (iii)–(a)
(D) (iv)–(c)

Correct Answer: (A) (i)-(d)

Thermophiles grow optimally at high temperatures like 67°C, making (i)-(d) the only correct pair among the options. Mesophiles prefer around 37°C, psychrophiles thrive at low temperatures, and halophiles require high salinity, not matching the other given pairings.

Question Breakdown

The question tests matching microbial groups to their optimal growth conditions from CSIR NET Life Sciences syllabus on extremophiles.

• (i) Thermophile: Matches (d) grows optimal at 67°C. Thermophiles thrive between 50-85°C, with many optima around 60-70°C.​

• (ii) Mesophile: Does not match (b) low temperature. Mesophiles grow best at 20-45°C, often 37°C (human body temperature).​

• (iii) Psychrophile: Does not match (a) 37°C. Psychrophiles prefer 0-15°C or below 20°C maximum.​

• (iv) Halophile: Does not match (c) high saline conditions accurately in options, but halophiles indeed grow optimally in high salt (e.g., >0.2 M NaCl), confirming mismatch here.​

Only option (A) pairs correctly.

Introduction to Extremophiles

Microorganisms adapt to extreme environments through specific optimal growth temperature and salinity needs. In CSIR NET Life Sciences, understanding thermophile mesophile psychrophile halophile optimal growth temperature helps solve matching questions like Q.38 accurately.​

Temperature-Based Classifications

Microbes group by preferred temperatures, crucial for ecology and biotechnology.

• Thermophile: Optimal growth 50-85°C, e.g., 67°C as in hot springs. Enzymes remain stable at high heat.​

• Mesophile: Optimal 20-45°C, peaking at 37°C. Includes human pathogens like E. coli.​

• Psychrophile: Optimal 0-15°C, maximum <20°C. Thrives in polar regions or deep oceans.​

Halophile Specifics

Halophiles favor high saline conditions (>0.2 M NaCl), not temperature extremes. Moderate types grow at 3-15% salt, extremes near saturation.​