15. Which of the following is correct?
A.A Winogradsky column is used to filter out microorganisms from a water sample taken from a deep black smoker
B.A Winogradsky column is used to demonstrate interactions and gradients that occur in aquatic environments
C.Both (a) and (b)
D.A Winogradsky column is used to filter out microorganisms from non-aquatic environments
16. Trickling filter comes under
D.none of these
17. Which of the following species in water reveal the presence of fecal pollution of human or animal origin?
D.All of these
18. Activated sludge undergoes
D.any of these
19. The rate of flux of oxygen in air is __________ to/than the rate of flux of oxygen in water.
20. __________ is an environment like __________ where microorganisms are functioning in an extremely thin film of water and where oxygen-containing air is close to them.
A.low oxygen diffusion environment; soils
B.high oxygen diffusion environment; soils
C.low oxygen diffusion environment; lakes
D.high oxygen diffusion environment; lakes
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