Biogeochemical Cycles Flashcards
7 cards from real Ecology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Biogeochemical Cycles flashcards as text
Which process converts atmospheric nitrogen (N₂) into ammonia (NH₃) that plants can use?
Answer: Nitrogen fixation
Nitrogen fixation, carried out by bacteria like Rhizobium, converts inert N₂ gas into ammonia that plants can absorb.
In the phosphorus cycle, what is the primary reservoir of phosphorus on Earth?
Answer: Rocks and sediments
Unlike carbon and nitrogen, phosphorus has no significant atmospheric reservoir and is stored primarily in rocks and sediments.
What process do decomposers perform that is essential to the nitrogen cycle?
Answer: Ammonification
Decomposers break down organic nitrogen in dead organisms into ammonia (NH₃) through ammonification.
Which human activity has most dramatically increased the rate of nitrogen entering ecosystems?
Answer: Synthetic fertilizer production via the Haber-Bosch process
The Haber-Bosch process industrially fixes atmospheric nitrogen into ammonia for fertilizers, roughly doubling natural nitrogen fixation rates globally.
During the sulfur cycle, which process releases sulfur dioxide (SO₂) into the atmosphere?
Answer: Volcanic eruptions and fossil fuel combustion
Volcanic eruptions and burning sulfur-containing fossil fuels are major pathways releasing SO₂ into the atmosphere.
What role do mycorrhizal fungi play in the phosphorus cycle?
Answer: They extend plant root surface area to absorb more phosphate from soil
Mycorrhizal fungi form symbiotic networks with plant roots, dramatically extending their reach to absorb phosphate ions from soil.
In a wetland ecosystem, which microbial process removes bioavailable nitrogen by converting nitrate back to N₂ gas?
Answer: Denitrification
Denitrification by anaerobic bacteria in waterlogged soils converts nitrate (NO₃⁻) back to N₂ gas, removing it from the ecosystem.