Lecture 23: Biogeochemical Cycling and Biomes Flashcards
-Energy Flow -Elemental Cycling -Biomes
What two conditions does life require to be met?
1) a flow of energy
2) the continual recycling of elements
What are autotrophs (primary producers)?
Organisms that produce organic matter via photosynthesis or chemosynthesis (primary production)
What are the two ways that primary producers use their produced biomass?
- they produce their own biomass
1) they use some of it to fuel their own metabolism, releasing energy in the form of heat
2) store some of the biomass for future use
What is gross production?
The production of organic matter before any use
What is net production?
The biomass that is left after it has been used to support its own metabolism
-net production = gross production - respiration
What are heterotrophs?
Organisms that build body mass by eating other organisms (secondary production)
What is aerobic respiration?
Respiration with the use of O2
What is anaerobic respiration?
Respiration without the use of O2
What are trophic levels?
They indicate how many feeding steps an organism is away from the autotroph level
What are decomposers?
Various bacteria that breakdown the dead organisms and waste materials, recycling their components
In what ways is energy lost through the trophic levels?
- respiration
- excretion of waste
What is a food chain?
Combination of trophic levels
What is a food web?
Multiple food chains woven together
What is usually the maximum amount of trophic levels in a food chain?
6
-Any more would require a large base of primary production
How many elements are considered essential for life?
24
What are macronutrients?
Elements required by all living things in large amounts
What are micronutrients?
Elements required in small amounts by all life or in moderate amounts by some forms of life
What are toxins?
Elements that are detrimental to living organisms
How can an element become a limiting factor?
It is not available at the right time, in the right amount or in the appropriate relative concentrations to each other.
What happens if an element becomes a limiting factor?
It could prevent growth of an organism, population, or even a species
What is Liebig’s Law (Law of the Minimum)?
The idea that growth is limited by the scarcest element
What is bioconcentration?
When a nutrient is more concentrated in an organism that in the environment
What is phytoremediation?
Using plants that can contain high concentrations of metals to clean up water, soil, or air
What are the two ways to cause bioconcentration?
1) Bioaccumulation
2) Biomagnification
What is bioaccumulation?
When a substance it taken in, not excreted at a comparable rate, becomes more concentrated in an organisms over time
What is biomagnification?
When a substance is passed from consumer to consumer up the food chain
What is a biochemical cycle?
It describes the movement of a chemical element or compound through the biosphere and the rest of the Earth system
What are some carbon cycle reservoirs?
- Atmosphere
- Hydrosphere
- Biosphere
- Geosphere
What is the largest sink for carbon?
Marine sediments
What are the steps in the carbon cycle?
- Carbon enters the atmosphere
- It is removed by photosynthesis which produces organic carbon compounds in living organisms
- Dissolved carbon is converted to bicarbonate during weathering
- In ocean it is then used by organisms to form biomass or shells, which then gets buried and stored in sediments
- Some organic carbon is preserved as dead organic matter
- It can ultimately be subducted and recycled into the mantle as graphite and diamond
How do some organisms acquire nitrogen?
In the form of nitrate ions and as ammonium ions
What sphere is phosphorus essential in?
The biosphere
What is the main phosphorus-bearing mineral?
Apatite
What is the main reservoir for apatite?
The crust
Where else can phosphorus be acquired?
Fish-eating birds excrete phosphorus as guano deposits which are mined for phosphorus
What are the most important attributes of a terrestrial biome?
- Temperature
- Precipitation
What are the most important attributes of an aquatic biome?
- Temperature
- Salinity
- Water depth
What are the characteristics of a Tundra biome?
- High altitude or high latitude
- Permafrost and few trees
- Long, cold winters and short, cool summer
- Small plants
What are the characteristics of a Boreal Forest biome (Taiga)
- South of Tundra
- Cold winters
- Short growing season
- Low precipitation
- Coniferous trees dominate
What are the characteristics of a Temperate Deciduous Forest biome?
- Broad-leaved deciduous trees
- Seasonal changes
- Soils rich in organic material, well-suited for agriculture
What are the characteristics of a Temperate Steppe biome (grassland)?
- Extensive temperate prairies
- Grasses with interconnected root system
- Rich soils, well-suited for agriculture
What are the characteristics of a Temperate Rainforest biome (Montane Forest)?
- Typical of the north-west coast of North America
- Mild winters
- Heavy precipitation
- Thick, tall forests
- Mainly coniferous trees but with some deciduous trees as well
What is a freshwater biome?
- Flowing water environments
- Standing water environments
What is a transitional aquatic biome?
-coastal, transitional between freshwater and marine biomes
What is the intertidal zone of a marine biome?
Near-shore, dynamic environment with high energy
What is the pelagic zone of a marine biome?
Open water
What is the benthic zone of a marine biome?
Bottom environment
What are the different zones of a lake?
- Littoral zone: warm, shallow area. Highly productive
- Limnetic zone: open water
- Photic zone: depth where light penetrates
- Profundal zone: depth with little or no light
