Multiple Choice QuestionsSome 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
The breakdown of detritus into small particles by detritivores is called
Leaching
Humification
Catabolism
Mineralization
Mineralization
E.
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.
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 .
The pioneer species in Xerarch and Hydrarch succession are respectively
Lichens and sedges
Lichens and rooted hydrophytes
Phytoplanktons and lichens
Lichens and phytoplanktons
Lichens and phytoplanktons
According to Robert Constanza, 50% of the total cost for ecosystem services goes to
Recreation
Soil formation
Nutrient cycling
Climate regulation
Climate regulation
Which of the following statement(s) regarding energy flow is/are false?
I. The detritus food chain begins with dead organic matter.
II. In aquatic ecosystem, detritus food chain is the major conduit for energy flow.
III. In terrestrial ecosystem a larger fraction of energy flows through grazing food chain.
IV. Producers belong to the first trophic level of the food chain.
II and III only
III and IV only
I and IV only
I and II only
I and II only
Match the following.
| Column I | Column II |
| A. Earthworm | 1. Catabolism |
| B. Bacterial and fungal enzymes | 2. Breaks down detritus into smaller particles |
| C. Accumulation of dark coloured amorphous substance | 3. Detritivores |
| D. Fragmentation | 4. Humus |
(A) - (3), (B) - (2), (C) - (4), (D) - (1)
(A) - (3), (B) - (l), (C) - (4), (D) - (2)
(A) - (2), (B) - (1), (C) - (4), (D) - (3),
(A) - (2), (B) - (3), (C) - (4), (D) - (1)
(A) - (2), (B) - (3), (C) - (4), (D) - (1)
The first trophic level in an ecosystem consists of
Primary producers
Primary consumers
Secondary producers
Secondary consumers
Secondary consumers
Select the correct statement
Phosphorus cycle is an example of gaseous nutrient cycle
The pyramid of biomass in sea is generally inverted
By the process of humification, soluble inorganic nutrients go down into the soil horizon
A given organism may not occupy more than one trophic level simultaneously
A given organism may not occupy more than one trophic level simultaneously
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