Biogeochemical Nutrient 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 Nutrient Cycles flashcards as text
Dimethylsulfoniopropionate (DMSP) produced by marine phytoplankton is important to the sulfur cycle because it:
Answer: Is converted to DMS gas, a major natural source of atmospheric sulfur
Phytoplankton produce DMSP, which is converted to dimethylsulfide (DMS) gas—the largest natural flux of sulfur from oceans to atmosphere.
Which of the following best explains why tropical soils are often nutrient-poor despite supporting lush vegetation?
Answer: Rapid decomposition and uptake cycle nutrients efficiently with minimal accumulation in soil
In tropical rainforests, warm wet conditions accelerate decomposition and plants immediately reabsorb nutrients, leaving little stored in the soil.
Carbon sequestration in wetlands occurs primarily through:
Answer: Slow decomposition under anaerobic conditions, accumulating organic matter as peat
Waterlogged, anaerobic conditions in wetlands slow microbial decomposition, allowing organic matter to accumulate as peat over centuries.
Iron (Fe) availability limits primary productivity in large regions of the open ocean primarily because:
Answer: Iron is essential for nitrogen-fixing enzymes and photosynthetic proteins but is scarce in open ocean water
Iron is a micronutrient required for photosynthesis and nitrogen fixation, but it is extremely scarce in remote ocean regions far from land dust inputs.
Which process in the sulfur cycle produces sulfuric acid and contributes to the weathering of rocks?
Answer: Oxidation of pyrite (FeS₂) exposed by mining or erosion
When pyrite is exposed to oxygen and water, sulfide is oxidized to sulfuric acid, which accelerates mineral weathering and can acidify streams.
In the concept of stoichiometry in ecology, the Redfield ratio (C:N:P ≈ 106:16:1) describes:
Answer: The average elemental composition of marine phytoplankton
The Redfield ratio describes the remarkably consistent atomic ratio of carbon, nitrogen, and phosphorus in marine phytoplankton biomass.
Enhanced weathering as a carbon sequestration strategy works by:
Answer: Spreading crushed silicate rocks on agricultural land to accelerate CO₂ absorption through chemical reactions
Crushed silicate rocks react with CO₂ and water to form bicarbonate, which flows to the ocean—effectively accelerating natural weathering that removes atmospheric CO₂.