Ecology Biogeochemical Nutrient Cycles 2

Question 1

Which process converts dissolved nitrate (NO₃⁻) back into atmospheric nitrogen gas (N₂)?

Accepted Answer

Denitrification

Answer

Denitrification is carried out by anaerobic bacteria that reduce nitrate to N₂, returning nitrogen to the atmosphere.

Question 2

In the phosphorus cycle, which reservoir holds the largest long-term store of phosphorus?

Accepted Answer

Sedimentary rocks

Answer

Sedimentary rocks are the primary long-term reservoir for phosphorus, which is released slowly through weathering.

Question 3

What is the term for the release of nutrients from decomposing organic matter back into inorganic form?

Accepted Answer

Mineralization

Answer

Mineralization is the microbial decomposition of organic compounds that converts nutrients into inorganic forms available to plants.

Question 4

Which gas released from wetlands and rice paddies is a significant product of the carbon cycle and a potent greenhouse gas?

Accepted Answer

Methane (CH₄)

Answer

Methane (CH₄) is produced by methanogenic archaea under the anaerobic conditions found in wetlands and flooded rice paddies.

Question 5

Sulfur enters the atmosphere naturally in large quantities primarily through which process?

Accepted Answer

Volcanic eruptions

Answer

Volcanic eruptions release large amounts of sulfur dioxide (SO₂) into the atmosphere as part of the natural sulfur cycle.

Ecology Practice Test