Why do raw materials brought to cities require a great amount of resources to be converted to a final product?

In which food chain microorganisms breakdown food formed by primary producers?

Which of the following statements is correct? A) Microorganisms are significant contributors to the total biomass on Earth. B) Microorganisms represent a much smaller amount of Earth's biomass than plants. C) Microorganisms represent a much smaller amount of Earth's biomass than animals. D) Microorganisms are significant in number, but not in overall biomass.

What is the nitrogen cycle?  (This question is asking for a general overview)

A food chain consists of grass, sheep, and human populations. If 7000 kJ in harvested grain is fed to the sheep, how much energy is available for the human population? A) 70 kJ B) 7.0 kJ C) 63 kJ D) 0.70 kJ E) 700 kJ

What is bioenergy from the biomass, especially, agricultural wastes?

(a) Define biofuel. (b) Describe three sources of biomass.

What is a "zero waste economy"?

What are tertiary consumers or top consumers?

What does domestic waste constitutes?