Secondary productivity in an ecosystem can be defined as:
1. | The amount of chemical energy, typically expressed as carbon biomass, that primary producers create in a given length of time. |
2. | The rate at which all the autotrophs in an ecosystem produce net useful chemical energy. |
3. | The rate of formation of new organic matter by consumers. |
4. | The amount of energy released by the action of detritivores and decomposers in an ecosystem. |
Suppose in an area, the energy present in total incident sunlight falling on primary producers is 10,00,000 J and about 10,000 J is converted by them into biomass. What percent of PAR have the primary producers been able to convert?
1. | 1 % | 2. | 2 % |
3. | 10 % | 4. | 20 % |
On the land, almost all primary production is performed by:
1. | Phytoplanktons | 2. | Algae |
3. | Mosses and Liverworts | 4. | Vascular plants |
The ecological pyramids that can never be inverted in a natural ecosystem include:
I: | pyramid of numbers |
II: | pyramid of energy in any ecosystem |
III: | pyramid of biomass in the sea |
1. Only II
2. Only III
3. Only II and III
4. All can be inverted
Energy flow and nutrient cycling are two important components of an ecosystem. What will be true comparison of the two?
1. | The amount of energy is much greater than the amount of nutrients |
2. | Organisms always need nutrients, but they don't always need energy |
3. | Nutrients are recycled, but energy is not |
4. | Organisms always need energy, but they don't always need nutrients |
Consider the two statements:
I: | Food chains rarely extend for more than 4 or 5 levels. |
II: | Consumers at each level convert, on an average, only about 10% of the chemical energy in their food to their own organic tissue. |
1. Both I and II are correct and II explains I.
2. Both I and II are correct but II does not explain I.
3. Only I is correct.
4. Both I and II are incorrect.
1. | A population | 2. | A species |
3. | A biological community | 4. | An ecosystem |
Statement I: | Entire biosphere is regarded as a global ecosystem by many ecologists. |
Statement II: | The global ecosystem is divided into terrestrial and aquatic ecosystem for convenience. |
1. | Only Statement I is correct. |
2. | Only Statement II is correct. |
3. | Both Statement I and Statement II are correct. |
4. | Both Statement I and Statement II are incorrect. |
1. | Stratification | 2. | Scarification |
3. | Standing crop | 4. | Standing state |
Statement I: | There is unidirectional movement of energy towards the higher trophic levels and its dissipation and loss as heat to the environment. |
Statement II: | Nutrients are never lost from the ecosystems, rather they are recycled time and again indefinitely. |