Ecology Biogeochemical Cycles 3

Question 1

Which of the following best describes a 'sink' in a biogeochemical cycle?

Accepted Answer

A reservoir that accumulates more of a substance than it releases

Answer

A sink is any reservoir that absorbs and stores more of a substance than it releases over a given time period.

Question 2

What happens to the carbon stored in peat bogs when they are drained and burned?

Accepted Answer

It is released as CO₂, contributing to atmospheric greenhouse gases

Answer

Draining and burning peat bogs releases centuries of stored carbon as CO₂, making them significant sources of greenhouse gas emissions.

Question 3

Which step in the nitrogen cycle converts ammonium (NH₄⁺) into nitrite (NO₂⁻) and then nitrate (NO₃⁻)?

Accepted Answer

Nitrification

Answer

Nitrification is a two-step aerobic process performed by bacteria like Nitrosomonas and Nitrobacter that oxidizes ammonium to nitrite then nitrate.

Question 4

How does the hydrological (water) cycle interact with the phosphorus cycle?

Accepted Answer

Precipitation and runoff transport dissolved phosphate from land to aquatic systems

Answer

Precipitation and surface runoff erode and transport phosphate ions from soils and rocks into rivers, lakes, and eventually the ocean.

Question 5

Eutrophication of lakes is most directly caused by excess input of which nutrients?

Accepted Answer

Nitrogen and phosphorus

Answer

Excess nitrogen and phosphorus from agricultural runoff fuel algal blooms in lakes, leading to oxygen depletion when algae decompose.

Ecology Practice Test