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
What is the Redfield ratio, and why is it important in marine biogeochemistry?
Answer: The ratio of C:N:P (106:16:1) in marine phytoplankton; it reflects nutrient demands and ocean stoichiometry
The Redfield ratio (C:N:P = 106:16:1) describes the consistent elemental composition of marine phytoplankton and is used to infer nutrient limitation in the ocean.
How do fire regimes influence the carbon cycle in grassland ecosystems?
Answer: Fires release carbon as CO₂ but grasslands recover quickly, and soil carbon stocks are largely maintained
While fire releases aboveground carbon as CO₂, grasslands store most carbon belowground in roots and soil, which recover rapidly after burning.
Nitrous oxide (N₂O) is produced mainly by which microbial process?
Answer: Incomplete denitrification under partially anaerobic conditions
N₂O is released as a byproduct of incomplete denitrification when soil oxygen levels are intermediate, making it a significant greenhouse gas from agricultural soils.
What is 'nutrient spiraling' in stream ecology?
Answer: The downstream transport of nutrients combined with cycling between dissolved and biological forms
Nutrient spiraling describes how nutrients in streams move downstream while simultaneously cycling between dissolved, microbial, and detrital forms, forming a longitudinal spiral.
Ocean acidification caused by rising atmospheric CO₂ most directly affects the marine calcium cycle by:
Answer: Reducing carbonate ion concentrations, inhibiting shell and skeleton formation
As oceans absorb CO₂, pH drops and carbonate ion concentration decreases, making it harder for organisms like corals and mollusks to build calcium carbonate structures.
What term describes the process by which phosphorus bound to iron oxides in lake sediments is released when bottom waters become anoxic?
Answer: Internal phosphorus loading
Internal phosphorus loading occurs when anoxic conditions reduce iron oxides in sediments, releasing bound phosphate into the water column and fueling algal blooms.
Which concept describes the idea that ecosystems are limited by whichever essential nutrient is in shortest supply relative to organism needs?
Answer: Liebig's Law of the Minimum
Liebig's Law of the Minimum states that growth is controlled by the scarcest essential resource, not by the total amount of resources available.