Ecology Biogeochemical Nutrient Cycles 3

Question 1

Eutrophication of lakes most commonly results from excess input of which two nutrients?

Accepted Answer

Nitrogen and phosphorus

Answer

Excess nitrogen and phosphorus from agricultural runoff fuel algal blooms that lead to eutrophication and oxygen depletion.

Question 2

In the global carbon cycle, which process represents the largest annual flux of carbon from the land surface to the atmosphere?

Accepted Answer

Soil respiration and decomposition

Answer

Soil respiration and decomposition release more CO₂ annually than any other land-based process, though it is balanced by photosynthesis.

Question 3

Which form of nitrogen is directly assimilated by most plants from the soil?

Accepted Answer

Ammonium (NH₄⁺) and nitrate (NO₃⁻)

Answer

Plants primarily absorb nitrogen in the inorganic forms of ammonium and nitrate through their roots.

Question 4

The Haber-Bosch process has dramatically altered the nitrogen cycle by:

Accepted Answer

Industrially fixing atmospheric N₂ into ammonia for fertilizer

Answer

The Haber-Bosch process uses high pressure and temperature to convert N₂ and H₂ into ammonia, enabling mass fertilizer production.

Question 5

What is the primary fate of phosphorus that erodes from land into the ocean over geological timescales?

Accepted Answer

It settles into marine sediments and eventually forms rock

Answer

Phosphorus carried to the ocean by rivers eventually settles into marine sediments, where it is incorporated into sedimentary rock over millions of years.

Ecology Practice Test

Ecology Practice Test

Ecology Biogeochemical Nutrient Cycles 3