Nutrient cycling Flashcards
(17 cards)
Define primary production.
Primary production refers to the synthesis of organic carbon compounds from carbon dioxide by autotrophs, such as plants and algae, using external energy sources like sunlight.
Define biomass.
Biomass is the total mass of a group of organisms – consisting of the carbon compounds contained in the cells and tissues
- Biomass accumulates whenever autotrophs and heterotrophs grow or reproduce
- The rate of biomass production is expressed in units of mass per area per time (kg m–2 day–1)
State the importance of primary production.
Foundation of Food Chains: Primary production provides the energy and organic matter that sustain all other organisms in an ecosystem.
Carbon Cycling: Autotrophs play a critical role in the carbon cycle by removing carbon dioxide from the atmosphere and storing it in biomass.
Ecosystem Services: High primary production supports biodiversity, stabilizes ecosystems, and contributes to services like oxygen production and climate regulation.
Define secondary production.
Secondary production is the accumulation of carbon compounds in biomass by animals and other heterotrophs, which ingest food and build these compounds into proteins and other macromolecules.
Explain why secondary production is lower than primary production in an ecosystem.
Energy Loss: Cell respiration results in a loss of biomass at every trophic level.
Trophic Decline: Secondary production declines with each successive trophic level, as energy and carbon are lost in respiration and waste.
State the key carbon fluxes in ecosystems.
The process of carbon transfer between a carbon source and a carbon sink is known as a carbon flux.
Photosynthesis: Absorption of carbon dioxide from the air or water, converting it into carbon compounds.
Feeding: Transfer of carbon compounds when organisms consume others.
Respiration: Release of carbon dioxide to the atmosphere by respiring cells.
State common carbon pools.
Atmosphere: Carbon dioxide.
Producers: Plants and algae store carbon in organic compounds.
Consumers: Animals store carbon in their bodies.
Decomposers: Fungi and bacteria store carbon temporarily.
Fossil Fuels: Coal, oil, and natural gas act as long-term carbon stores.
Define carbon sinks and carbon source.
Carbon sink is an ecosystem that absorbs more carbon than it releases.
Carbon source is an ecosystem that releases more carbon than it absorbs.
Define combustion.
Combustion is a chemical reaction where carbon compounds react with oxygen, producing
* carbon dioxide and water
* energy in the form of heat and light
This process occurs when various carbon-containing materials are burned
State the types of combustion sources.
Biomass combustion is part of the short-term carbon cycle, as the carbon released was recently absorbed during plant growth
Peat combustion releases carbon stored over thousands of years
Fossil fuel combustion releases carbon that has been sequestered for millions of years
State the effect of human activities on combustion rates.
Humans are using the combustion of fossil fuels to produce energy for various uses (electricity, etc.)
* Fossil fuels form as a consequence of incomplete decomposition of biomass (due to anoxic or acidic conditions)
* When the biomass is compressed under sediment, heat and pressure force out any impurities and remove any moisture
* Peat and coal are formed from terrestrial organisms in waterlogged soils, while oil and natural gas are formed from marine organisms
State the trends evident from the Kneeling Curve.
The following trends are evident from the Keeling Curve:
- CO2 levels fluctuate annually (lower in the summer months when long days and more light increase photosynthetic rates)
- Global CO2 trends conform to northern hemisphere patterns as it contains more of the planet’s land mass (i.e. more trees)
- CO2 levels are steadily increasing year on year since the industrial revolution (due to increased burning of fossil fuels
- Atmospheric CO2 levels are currently at the highest levels recorded since measurements began
State the two of the main carbon fluxes within ecosystems.
Two of the main carbon fluxes within ecosystems are photosynthesis and cell respiration
- Photoautotrophs take up carbon dioxide when they photosynthesise and convert it into carbon compounds (which are stored in their tissues as biomass)
- Most autotrophs and heterotrophs will release carbon dioxide when they break down biomass via aerobic respiration (to produce ATP)
Explain the interdependence of aerobic respiration and photosynthesis.
Autotrophs and heterotrophs are interconnected through the cycling of oxygen and carbon dioxide:
* Autotrophs produce oxygen, supporting respiration in heterotrophs.
* Heterotrophs release carbon dioxide, fueling photosynthesis in autotrophs.
Explain how levels of atmospheric carbon dioxide are influenced by the relative rates of photosynthesis and respiration.
If net photosynthetic rates are higher than respiration rates, atmospheric carbon dioxide levels should drop
If net respiration rates are higher than photosynthetic rates, atmospheric carbon dioxide levels should increase
State the key nutrient cycles.
The carbon cycle.
The nitrogen cycle.
The phosphorus cycle.
Outline the process of nutrient cycling.
Autotrophs obtain inorganic nutrients from the environment (air, water or soil) and convert them into organic compounds
Heterotrophs ingest these organic compounds as part of their diet and use them for growth and respiration, releasing inorganic byproducts
When organisms die, saprotrophs decompose the remains and release inorganic materials back into the environment
The return of inorganic nutrients to the environment ensures the continual supply of raw materials for the autotrophs
