Question

The apparatus used for the extraction of cysts from soil is:

• A. Cobb’s sieve
• B. Fenwick can
• C. Oostenbrink elutriator
• D. Baermann’s funnel

Hint:

Oostenbrink elutriator uses water flow and sedimentation for nematode extraction from soil.

Answer 1

The Correct Option is C

The Oostenbrink elutriator is commonly used for extracting nematode cysts and other small soil organisms by elutriation, which separates organisms based on size and density.

Answer 2

Elimination approach:
Cobb's sieve and Baermann's funnel are used to isolate motile (vermiform) nematode stages from soil or plant tissue through sieving or migration in water, not for separating dense cyst bodies. The Fenwick can floats cysts of Heterodera or Globodera species out of a soil suspension using surface tension, but it is designed for small, relatively clean samples and cannot efficiently process bulk soil. The Oostenbrink elutriator instead passes a continuous stream of water and air bubbles upward through a soil column, separating particles by size and density and allowing high-throughput extraction of cysts along with other nematodes from large soil samples, which is why it is the apparatus specifically cited for this purpose.
Hence, the correct answer is Oostenbrink elutriator.