Ecology Biogeochemical Cycles 2

Question 1

Which process converts atmospheric nitrogen (N₂) into ammonia (NH₃) that plants can use?

Accepted Answer

Nitrogen fixation

Answer

Nitrogen fixation, carried out by bacteria like Rhizobium, converts inert N₂ gas into ammonia that plants can absorb.

Question 2

In the phosphorus cycle, what is the primary reservoir of phosphorus on Earth?

Accepted Answer

Rocks and sediments

Answer

Unlike carbon and nitrogen, phosphorus has no significant atmospheric reservoir and is stored primarily in rocks and sediments.

Question 3

What process do decomposers perform that is essential to the nitrogen cycle?

Accepted Answer

Ammonification

Answer

Decomposers break down organic nitrogen in dead organisms into ammonia (NH₃) through ammonification.

Question 4

Which human activity has most dramatically increased the rate of nitrogen entering ecosystems?

Accepted Answer

Synthetic fertilizer production via the Haber-Bosch process

Answer

The Haber-Bosch process industrially fixes atmospheric nitrogen into ammonia for fertilizers, roughly doubling natural nitrogen fixation rates globally.

Question 5

During the sulfur cycle, which process releases sulfur dioxide (SO₂) into the atmosphere?

Accepted Answer

Volcanic eruptions and fossil fuel combustion

Answer

Volcanic eruptions and burning sulfur-containing fossil fuels are major pathways releasing SO₂ into the atmosphere.

Ecology Practice Test

Ecology Practice Test

Ecology Biogeochemical Cycles 2