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Ecosystem

Multiple Choice Questions

221.

Living in same habitat organisms of same species from:

biosphere
community
population
niche

222.

By anaerobic process, the cow dung is used to produce :

methane
butane
ethane
propane

223.

As insecticides reach at higher trophic level in food chain their concentration :

increases
become irregular
remain constant
decreases

224.

The term 'ecosystem' was coined by :

E.P. Odum
A.G. Tansley
Carl Mobious
W. Clementus

225.

The food chain starts from :

consumer
producer
decomposer
nitrogen fixation

226.

Some students, during a study, caught, marked and released 80 fishes in a pond. Later 100 fishes were caught at random. Among these 40 were found to be marked. What is the approximate number of fishes in the pond?

50
100
200
4000

227.
The breakdown of detritus into small particles by detritivores is called

Leaching

Humification

Catabolism

Mineralization

Mineralization

Fragmentation

Decomposition is the process by which organic substances are broken down into a more simple organic matter. The important steps in the process of decomposition are-

1. Fragmentation: Breakdown of detritus into smaller particles by the use of detrivores such as earthworm.

2. Leaching: Using this process, water soluble inorganic nutrients go down into the soil horizon and get precipitated as unavilable salts.

3. Catabolism: Bacterial and fungal enzymes degrade detritus into simpler inorganic substances.

4. Humification: It is the process of formation of humus. It is highly resistant to microbial action.

5. Mineralisation: Degradation of humus by microbes and release of inorganic nutrients is known as mineralisation.

228.

Which of the following statements about Productivity is true?

Primary productivity of all ecosystems is a constant
The annual net primary productivity of the whole of the biosphere is 17 billion tons (dry weight) of organic matter
Net primary productivity is the amount of biomass available for consumption by carnivores
Secondary productivity is defined as the rate of formation of new organic matter by decomposers .
Secondary productivity is defined as the rate of formation of new organic matter by decomposers .