The three steps of decomposition occur:
1. sequentially, with catabolism being the last step.
2. sequentially, with leaching being the last step.
3. simultaneously.
4. sequentially, but not in a particular order.
Humus:
1. Is easily broken down by microbes
2. Undergoes decomposition rapidly
3. Serves as a reservoir of nutrients
4. Yields organic nutrients on mineralization
Decomposition of detritus is rapid when:
1. It is rich in lignin and chitin
2. Ambient temperature is low
3. Environment favours anaerobiosis
4. It predominantly contains nitrogen and sugars
What percentage of photosynthetic active radiation is captured by plants?
1. | 1 – 5 | 2. | 2 – 10 |
3. | 50 | 4. | 90 |
Organisms that are capable of conversion of inorganic material into organic material with the help of the radiant energy of the sun include:
I: | Plants |
II: | Photosynthetic bacteria |
III: | Chemosynthetic bacteria |
1. | I only | 2. | I and II only |
3. | I and III only | 4. | I, II, and III |
Primary carnivores are, most aptly, characterized as:
1. | Secondary producers | 2. | Primary consumers |
3. | Secondary consumers | 4. | Tertiary consumers |
The detritus food chain:
I: | begins with dead organic matter |
II: | is the major conduit of energy flow in aquatic ecosystem. |
1. Only I is correct
2. Only II is correct
3. Both I and II are correct
4. Both I and II are incorrect
In a terrestrial ecosystem, a much larger fraction of energy flows through the:
1. | DFC | 2. | GFC |
3. | Either of DFC or GFC | 4. | Nither of DFC nor GFC |
In an aquatic food chain, zooplankton occupy which trophic level?
1. | First | 2. | Second |
3. | Third | 4. | Fourth |
Organisms at each trophic level depend on those at the lower level trophic level for their energy demands except:
1. | Primary consumers | 2. | Secondary consumers |
3. | Tertiary consumers | 4. | Decomposers |