The productivity in an aquatic ecosystem is least likely to be limited by:

1.	nitrogen	2.	carbon
3.	phosphorus	4.	iron

In an ecosystem which of the following can never by inverted?
1. pyramid of numbers
2. pyramid of energy
3. pyramid of biomass
4. all can be inverted

In boreal forests soils contain large amounts of carbon but the primary production is low compared to other types of forests. This can be explained by:
1. high rates of herbivory
2. slow weathering of rocks
3. periodic fires in the forests
4. restricted decomposition

The amount of water required for a crop plant to produce one kilogram of food is approximately:
1. 1 Kg
2. 10 Kg
3. 100 Kg
4. 1000 Kg

A herbivore eats 4,000 J of plant material. 2200 J is indigestible and is eliminated as feces. 1,600 J are used in cellular respiration. What is the approximate production efficiency of this animal?

In the Hubbard Brook experiment, when the part of the forest was cut down
1. water flowed through the system at a greater rate
2. nitrogen began to accumulate in the system
3. more phosphorus was lost in stream runoff
4. carbon dioxide is released into the environment

Choose the correct chronological order [lowest to highest] of the production efficiency of the given animals:

What is the percent of atmospheric carbon dioxide that is fixed annually by photosynthesis?
1. 70%
2. 36%
3. 10%
4. 1%

Top predators are especially endangered primarily because:
1. The population size would be small
2. Their food requirement is huge
3. They are more prone to diseases
4. They are usually outcompeted by prey

A primary consumer amongst the following would be: