Test yourself

1 Microorganisms are essential in the_of elements in the biosphere.

2 _organisms fix carbon dioxide into_compounds. These are _ by heterotrophs and carbon dioxide is returned to the

3 Nitrogen-fixing bacteria need to keep the interior of their cells oxygen-free because of the sensitivity of the_towards oxygen.

4 The release of inorganic nutrients from organic compounds as a result of microbial metabolism is termed__

5 Powdered_is added to alkaline soils in order to encourage the activity of__bacteria, which leads to a reduction in pH.

6 Certain photosynthetic bacteria are able to use hydrogen sulphide as a _of_in the reduction of carbon dioxide.

7 _often acts as the limiting nutrient in an ecosystem, because it is only available in an insoluble form.

8 The_are the major group of bacteria found in a typical soil.

9 _are complex populations of microorganisms held together within a polysaccharide matrix.

10 The microbial population of a aquatic habitat is influenced by the availability of_and__

11 The profundal zone is the name given to deep waters characterised by the absence of__

12 In the benthic zone, the microbial population comprises mostly_


13 A high organic content in a body of water encourages the growth of _, which may lead to a depletion of available__

14 Unicellular photosynthesisers such as the_and_are collectively termed__

15 Molecular techniques such as FISH ( _ _ _

_) enable the detection of microorganisms it is not possible to culture by conventional means.

16 The effectiveness of a wastewater treatment regime may be judged by the reduction in the___(_).

17 The two forms of secondary wastewater treatment are__

18 In anaerobic digestion, organic matter is converted into _ and

19 The principal component of wood that is susceptible to biodeterioration is __However the white rot fungi can also degrade__

20 The dry rot fungus Serpula lacrymans is able to conduct water via thick strands of hyphae called__

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