Which of the following pyramids can never be inverted in a natural ecosystem?

1. pyramid of numbers

2. pyramid of energy

3. pyramid of biomass

4. all can be inverted 

The earth is an open system with respect to

1. organisms

2. chemicals

3. energy 

4. all of the above

Plants capture approximately __________________ of the sun's energy while other trophics levels capture about _________________ of the energy available to them in their food.

1. 1%, 10%

2. 10%, 60%

3. 10%, 1%

4. 60%, 10%

Which trophic level is incorrectly defined?
1. Carnivores- secondary or tertiary consumer
2. Decomposer- microbial heterotrophs
3. Herbivores - primary consumer
4. Omnivores - Molds, yeast and mushrooms

Nitrogen gas makes up nearly 80% of Earth's atmosphere, yet nitrogen is often a limiting factor for plant growth. Why ?
1. The atmospheric form of nitrogen cannot be used by plants.
2. Nitrifying bacteria remove usable nitrogen from the soil more repidly than plants can absorb it.
3. Atmospheric nitrogen dissolves readily in the soil but is washed out with every rainfall.
4. Plants must absorb nitrogen through their roots, which are not in contact with the atmosphere.

In general, the biomass in an ecosystem will be greatest at the trophic level comprising.

1. secondary consumers

2. primary consumers

3. producers

4. tertiary consumers

Consider the following two statements:

1. Both l and ll are correct and ll explains l

2. Both l and ll are correct but ll does not explain l

3. l is correct but ll is incorrect

4. l is incorrect but ll is correct

What percent of energy in the sunlight availble to the primary producers is converted by them into net primary productivity ?
1. 1
2. 2
3. 5
4. 10 

Both hydrach and xerarch successions:

1. Take same time

2. Have similar sere

3. Lead to mesic conditions

4. Have same pioneer species

The second trophic level in a lake is:

1. Phytoplankton

2. Zooplankton

3. Benthos

4. Fishes