CAS GE 100 Lecture Notes - Lecture 4: Biological Pump, Nitrogen Cycle, Primary Production

• School: Boston University
• Department: Geography & Environment
• Course: CAS GE 100
• Professor: Aaron Garrett

Document Summary

Flow (mass/time) storage (mass) flow (mass/time) In (time t) storage out (time t +1) Storage(t) + in(t) out(t) = storage (t+1) Spontaneous flows: matter flows high to low concentrations, no energy required. Non-spontaneous flows: matter flows from low to high concentrations, energy is needed. Most autotrophs get nutrients from environment in an inorganic form: nitrogen as nitrate (no3, phosphorus as phosphate (po4) Nutrients are transported in water through transpirations: pressure gradients (spontaneous flow) Growth of plants is limited by the nutrient which is least abundant or available relative to the needs of the plant. Nitrogen fixing bacteria, fertilizers, decomposition, animal feces. All human proteins made from 20 amino acids. Non-essential amino acids: can be made by the body, 10 (e. g. cysteine) Essential amino acids: cannot be made by the body, 10 (e. g. tryptophan) Substances left over from metabolic processes that cannot be used by the organism and must be excreted. Residence time (flow relative to size of storage)