The food chain starts from :

• consumer

• producer

• decomposer

• nitrogen fixation

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

The breakdown of detritus into small particles by detritivores is called

• Leaching

• Humification

• Catabolism

• Mineralization

• Mineralization

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

138.

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