Primary succession takes a very long time when compared to secondary succession, primarily, because:
1. immigration of pioneer species takes time
2. soil formation is a very slow process
3. there is a low availability of ecological niches
4. environmental conditions are highly variable
Consider the given two statements:
I: | In most ecosystems, all the ecological pyramids are largely upright. |
II: | Pyramid of energy can be a notable exception to the above rule. |
1. Both I and II are correct.
2. Both I and II are incorrect.
3. Only II is correct.
4. Only I is correct.
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 |
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
In an open ocean, the pyramid of biomass is often inverted. How can this support higher trophic levels?
1. | The food produced by primary producers is of high quality |
2. | The primary producers grow and reproduce at high rates |
3. | Primary producers are very abundant. |
4. | The predators at higher trophic levels are very efficient |
An important feature of the phosphorus cycle is that its reservoir is in:
1. aquifers
2. soil and rocks
3. the atmosphere
4. the sun
Net primary productivity is the gross primary productivity minus:
1. | that which is consumed by herbivores |
2. | that which is consumed by the producer in metabolism |
3. | secondary productivity |
4. | loss due to mortality |
Climax community is in a state of :
1. Non-equilibrium
2. Equilibrium
3. Disorder
4. Constant change
During the process of ecological succession, the changes that take place in communities are :
1. Orderly and sequential
2. Random
3. Very quick
4. Not influenced by the physical environment
Pyramid of numbers is :
1. Always upright
2. Always inverted
3. Either upright or inverted
4. Neither upright nor inverted