Lecture 9
Explain which abiotic factors affect the biological community, and how those abiotic factors influence energy flow through an ecosystem.
Temperature, precipitation, and nutrients. The higher the temperature combined with more precipitation and a good source of nutrients = higher primary productivity and more energy flow
Explain what trophic pyramids (pyramids of energy) represent
The amount of energy at each trophic level.
Explain why primary production is an ecosystem service
The more primary production that is occuring, the more oxygen that is produced for humans to breathe.
Identify the major groups of decomposers
Bacteria, archaea, fungi (in eukarya), and a few other eukaryotes
Define nitrogen fixation
The process in which nitrogen gas (N2) is converted into ammonia (NH3), a form biologically useful to primary producers.
Describe the major groups of primary producers, including being able to place them in the three domains of life; contrast which producers are dominant in terrestrial vs. aquatic habitats
No archaea are primary producers. Chemoautotrophs are uniquely prokaryotic, live in the deep sea, and obtain chemical energy from chemical bonds of inorganic compounds. Photoautotrophs are eukaryotic and include algae, diatoms, and dinoflagellates (these are all aquatic)
Describe the nutrients that typically limit primary productivity in terrestrial, marine, and freshwater habitats
In marine systems, mainly nitrogen and iron. In terrestrial, mainly nitrogen. In freshwater, phosphorous
Explain the global patterns in primary productivity and what causes these patterns
Primary productivity increases as you get closer to the equator (except for deserts). This is because there is generally higher precipitation and warmer temperatures, and more nutrients due to faster cycling rates (erosion)
Describe the form of phosphorus that can be used by primary producers
Phosphate
What is eutrophication?
The process in which added nutrients lead to a great increase in the populations of algae and cyanobacteria.
Describe the defining traits of land plants, vascular plants, seed plants, and angiosperms.
Land plants: an alternation of generations, with a multicellular haploid stage followed by a multicellular diploid stage
Vascular plants: Vascular system comprised of xylem and phloem that can transport water and nutrients, respectively.
Seed plants (angiosperms and gymnosperms): production of pollen and seeds
Angiosperms: Production of flower and fruit
Explain why energy flows within and between ecosystems, and why energy does not cycle
Energy enters an ecosystem through the sun, and then is released overtime as heat.
Explain in general how a biogeochemical cycle works, including how nutrients enter ecosystems and how they are altered within ecosystems
A biogeochemical cycle circulates elements in different forms through different reservoirs. They enter the ecosystems through uptake in primary producers after fixation by decomposers. They are altered during different metabolic processes.
Describe why heterotrophs need P atoms
Heterotrophs need P atoms to make ATP for energy
What is a dead zone in an ocean and what is it caused by?
Caused by eutrophication, over bloom of algae due to excess nutrients cases increase in detrital pool which increases numbers of decomposers which cause the amount of oxygen in the water to decrease
Describe the sources of energy used by primary producers, and explain the difference between photoautotrophs and chemoautotrophs
Photoautotrophs receive energy through sunlight, chemoautotrophs receive energy through chemical bonds
Explain why primary production is necessary for energy transfers and how chemoheterotrophs obtain both energy and carbon atoms
Primary production is necessary to incorporate energy into an ecosystem that is able to potentially move up the trophic levels for other organisms to use. Chemoheterobtrophs obtain carbon through consuming other organisms, and energy from making ATP molecules through cellular respiration.
Explain the abiotic factors that limit rates of decomposition in terrestrial and aquatic ecosystems
Explain the abiotic factors that limit rates of decompositionin terrestrial and aquatic ecosystems
Describe the major atmospheric pool of nitrogen, the forms of nitrogen that can be used by primary producers
The major pool of nitrogen is in the atmosphere, nitrogen can be used by primary producers as nitrate and ammonium (both inorganic & bioavailable).
For fungi, identify their domain, and describe basic aspects of their biology: how they acquire nutrients, their cell wall structure
They are in the domain eukarya, have cell walls made of chitin, are chemoheterotrophs (release digestive enzymes and then absorb nutrients from the environment or other organisms), many have mycelium made of hyphae, but not all (example: yeast, unicellular)
Explain the distinction between NPP and GPP, describe ways in which ecologists measure these, and understand the relationship between NPP, GPP, and respiration
GPP is NPP minus cellular respiration. Ecologists can measure this by harvesting and weighing dry biomass, remote sensing, and using light and dark bottle experiments.
Explain why the transfer of energy among trophic levels is not efficient and explain how this limits the length of food chains; describe how much energy (average value, expressed as %) is transferred from one trophic level to the next trophic level in ecosystems.
It is not efficient because not all matter at each level is consumed, and not all of what is consumed is assimilated, and not all of what is assimilated is used as new biomass. Roughly 10% is transferred from one level to the next.
Explain how decomposers influence nutrient cycling and why ecosystem services,such as primary production,would cease without them
They fix nutrients into a useable form for the plant to uptake. If plants did not have access to these nutrients in the forms decomposers provide them in, they would not be able to grow.
Describe how humans have altered the nitrogen cycle, and link this with eutrophication
Humans have altered the phosphorous cycle through mining and producing phosphorous rich fertilizer, and through growth of livestock which produce phosphorous rich manure
Explain what the biogeochemical cycle is
The path that an element takes as it moves from one compartment or pool to another within an ecosystem