Cycles Of Matter

Scientists classify the nitrogen, carbon, and water cycles as biogeochemical cycles

Carbon cycles through the biosphere in all of the following processes EXCEPT a. photosynthesis. c. burning of fossil fuels. b. transpiration. d. decomposition of plants and animals.

Nitrogen fixation is carried out primarily by a. humans. c. bacteria. b. plants. d. consumers

Nitrogen fixation is carried out primarily by a. humans. c. bacteria. b. plants. d. consumers

What can happen after a lake receives a large input of a limiting nutrient? a. An algal bloom occurs. b. Algae begin to die and decomposers take over. c. Nitrogen compounds are recycled. d. The concentration of oxygen drops below the necessary level.

The chemical substances that an organism requires to live are called nutrients.

A lake that is protected from receiving the runoff from a cultivated field is likely to remain a healthy ecosystem.

Which steps in the figure above show the carbon cycle passing through living systems?

Living organisms require nitrogen to make nitrates and nitrites, which are used to build _______________________. a. sugars c. starches b. proteins d. glucose

The rate at which organic matter is created by producers in an ecosystem is called a. a limiting nutrient. c. an algal bloom. b. fertilization. d. primary productivity.