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
In the marine carbon cycle, what is the 'biological pump'?
Answer: The process by which phytoplankton fix carbon and sink organic matter to the deep ocean
The biological pump describes how phytoplankton photosynthesis and subsequent sinking of dead organic matter transfers carbon from surface waters to the deep ocean.
What is the primary source of phosphorus for terrestrial ecosystems over geological timescales?
Answer: Weathering of phosphate-containing rocks like apatite
The slow weathering of phosphate minerals in rocks (primarily apatite) is the original source of phosphorus for terrestrial nutrient cycles.
How does deforestation affect the local carbon cycle?
Answer: It reduces carbon storage as trees are removed and soil carbon is released
Deforestation removes living carbon stores and often involves burning, releasing stored carbon as CO₂ while eliminating future uptake capacity.
Which gas produced during the anaerobic decomposition of organic matter in wetlands is a potent greenhouse gas?
Answer: Methane (CH₄)
Methanogenic archaea in oxygen-depleted wetland soils produce methane (CH₄), which has about 25 times the warming potential of CO₂ over 100 years.
What is nitrogen mineralization in the context of soil ecology?
Answer: The release of inorganic nitrogen from decomposing organic matter
Nitrogen mineralization is the microbial breakdown of organic nitrogen compounds in soil into inorganic forms like ammonium that plants can absorb.
Which of the following is an example of a 'slow' part of the carbon cycle?
Answer: Carbon storage in fossil fuels over millions of years
The formation of fossil fuels from ancient organic matter over millions of years represents a very slow reservoir in the carbon cycle, distinct from rapid biological cycling.
Lightning-mediated nitrogen fixation contributes to the nitrogen cycle by:
Answer: Breaking N₂ bonds and allowing atmospheric N to form nitrates that enter soil via rain
The energy from lightning breaks the triple bond of N₂, allowing it to combine with oxygen to form nitrogen oxides that dissolve in rainwater as nitrates.