Lecture 27 11/14 (Dr. Maybruck 12); Biosphere

Audio for todays lecture is available here.

• SLIDE 1 handout 11/14
• • Biosphere (1 giant ecosystem) – region of earth that contains living organisms
• o Living organisms are supported by the interactions that are occurring between abiotic (non living matter) and biotic (living matter) processes.
• • Levels of the Biosphere (ultimately connected together)
• o Lithosphere – the land (and a few miles into the earth)
• o Hydrosphere – aquatic
• o Atmosphere – few miles into the air
• • Ecosystem: Communities of organisms that are interacting with one another and their physical environment
• • Community: populations interacting with one another and their environment
• • Population: group of organisms of all the same species
• • Habitats: location where the populations live
• • Niche: poplulations occurring in the community serve a specific role
• o Example: protozoans consuming bacteria
• SLIDE 2 Components that make an ecosystem work
• • Producers consumers decomposers → different trophic(feeding) levels.
• o Primary – autotrophic organisms. Convert CO2¬ into glucose.
• • Photoautotrphs – use the sun as an energy source to convert CO2 into glucose
• • Chemoautrophic – found in hydrothermal vents. Get nutrients other than the sun
• o Consumers and decomposers
• • Heterotrophs – convert glucose into CO2. Consumers are ultimately responsible for consuming primary producers.
• • Decomposers – consume primary and consumers. Consume them as dead organic matter.
• Example: bacteria, fungi, invertebrates, scavenger animals
• • Diagram on handout illustrating components of ecosystem
• o Energy is lost going from step to step
• o NOTE: energy is not cycled back into the system. Ultimately energy is lost through heat. What IS cycled is carbon and nutrients (elements).
• SLIDE 3
• • Example of energy lost
• o Start with 100 energy
• o Only 10 units of energy to the next level
• o Only 1 unit of energy goes on to the secondary consumers
• o Only .1 unit of energy goes to the final consumer
• • It is important that the primary consumers are sustained – therefore we are sustained
• SLIDE 4
• • Carbon – considered separate from nutrients but still critical
• • Essential Nutrients: nitrogen, phosphurus
• • Liebig’s Law of the minimum – an organisms growth is going to be restricted when the elements (carbon, nitrogen and phosphorus) are not at levels required for the organisms growth.
• • Biogeochemically cycle – ensures all trophic levels receive proper nutrients. The most important part of this cycle is biological processes.
• • Notes on Carbon Cycle
• o CO2 found in high concentrations in aquatic system and aquatic life
• o Photosynthetic organisms that occur on land and have access to this CO2
• o In aquatic life microorganism are the primary producers → algae, bacteria, protozoans
• o Cow consumes glucose of the grass and converts it to CO2
• o Autotrophic organisms break down glucose and produce CO2
• o Limestone erosion: limestone is created from the shells of animals condensing together and being buried. Shells form from the combination of calcium and CO2 → forms calcium carbonate. This makes up the shell of the organism.
• SLIDE 5
• • Nitrogen cycle [how do we get nitrogen to primary producers]
• o Plants prefer to have ammonium rather than nitrate. They would have to break nitrate to ammonium.
• o Ammonium and nitrate are inorganic sources of nitrogen.
• • Animals consume organic matter which is where the nitrogen is.
• • Primary producers get inorganic nitrogen through thee different methods
• o Precipitation – “butloads” of nitrate
• o Erosion of rock (which is weathered by precipitation)
• o Ammonification, nitrification, denitrification, and nitrogen fixation
• SLIDE 6 - ammonification
• o When the heterotrophic organisms is consuming nitrogen and it has excess it will release the extra ammonium into surroundings → ammonium pool
• o Precipitation, weathering and excretion also contribute to the ammonium pool
• Slide 7 nitrification
• o Overall purpose is to turn CO2 into glucose.
• o CO2+H20 → CHO+O2
• o Nitrosomonas (chemoautotrphic)
• • CO2+NH4→CHO+NO2 (nitrite)
• o Nitrobacter
• • CO2+NO2(nitrite) → CHO+NO3 (Nitrate)
• Slide 8 denitrification
• o Looking at heterotrophic bacteria (convert glucose to CO2)
• o These bacteria have an anaerobic metabolism.
• o Animal respiration
• • CHO+O2→CO2+H2O
• o Denitrification (anaerobic process)
• • CHO+NO3(nitrate) → CO2+N2 (nitrogen gas)
• Slide 9 Nitrogen fixation (another example of a anaerobic organism)
• o Nitrogen fixing organism get it from denitrification or from the atmosphere
• o CHO+N2 → CO2+NH4
• o Mutualistic – intimate association with benefits for each organism
• • Rhizobia infects roots of legumes resulting in root nodules. This creates anaerobic environment in root. When the nitrogen gas goes into the root it is converted to ammonium and then the plant can use it. The plant gets ammonium the organism gets nutrients.