Exam 23: Biogeochemical Cycles

The source of all carbon in living organisms is

Which of the following nutrients has a cycle that does not contain an appreciable atmospheric phase?

In ecosystems,internal cycling is dominated by

Precipitation can be a significant input of nutrients in ecosystems.

Which of the following nutrients is most closely linked to the energy cycle in ecosystems?

Carbon is released into the atmosphere as carbon dioxide through the process of

The biogeochemical cycles of one ecosystem are typically independent from those of other ecosystems.

Humans have altered the nitrogen cycle by burning fossil fuels.

Microbial decomposition of organic matter results in NH4+ production through a process called ________.

Some nutrients are ________ from the soil and carried out of ecosystems by underground water flow to streams.

Oxygen is taken up by plants during photosynthesis.

Precipitation brings appreciable quantities of nutrients into ecosystems that are collectively called ________.

Atmospheric sulfur dioxide returns to Earth in rain as weak sulfuric acid.

Which of the following cycles is thought to be most under biological control?

The major process regulating phosphorus availability for net primary production is the internal cycling of phosphorus from

Plant roots compete with Nitrosomonas and Nitrobacter for ammonium in soil.When these bacterial groups acquire the ammonium,they turn it into

Stratospheric ozone shields the planet from biologically harmful ultraviolet radiation.

Seasonal fluctuations in atmospheric carbon dioxide concentrations are greater in the Northern Hemisphere than in the Southern Hemisphere.

Nutrients deposited on leaves as dust and materials leached from leaves through insect action are most often transported to the forest floor by

The major source of free oxygen that supports life on Earth is the ________.