PSY320H1 Lecture Notes - Lecture 3: Chemosynthesis, Ecological Pyramid, Food Web
Lecture 3
Ecosphere
• Includes the biosphere and the region where living organisms interact with the other components
of the Earth System
• Entropy: degree of disorder or randomness
• When energy is changed from one form to naother, some is lost as a non-usable form of energy
o No energy conversion is 100% efficent (some is released as heat = increases entropy)
Energy Flow Through Systems
• There are producers, consumers, and decomposers
• Producers: are autotrophs that make their own food
o Need eternal source of energy
o There are two types of autotrophs; phototrophs & chemotrophs
• Consumers are heterotrophs which utilization respiration to make energy (opposite of
photosynthesis)
o Include, herbivores, omnivores, carnivore, and detrivores
• Hydrothermal vents host entire communities that thrive in high temp and pressure on the ocean
floor these organisms use chemosynthesis in which they used chemical energy (sulfate instead of
ligth) to make sugar and sulfuric acid (energy)
▪ 6CO2 + 6H20 + 3H2S C6H12O6 + 3H2SO4
Energy flow
• Trophic level: each step in this flow of energy
• Food chain; straight path (doesn't show energy)
o Energy flows linearly
o Producer → priary cosuer → secodary cosuer → tertiary cosuper →
decomposer
• Food web is an interconnected food chain (more realistic)
• Most energy organisms use is lost as waste heat through respiration which means there is less and
less energy available at each successive trophic level
o This creates a trophic pyramid where most of energy/biomass/numbers are at the bottom
up
Biomass
• Energy is converted to biomass through primary productive
• Amount of living organic matter in a certain area
• Phytomass: photosynthesizing plant biomass
• 99% of all biomass
• Productivity: rate at which organic matter is formed
• Primary production = conversion of solar energy to chemical energy by autotrophs
• Net primary production (NPP): energy available for hetetrophs
• Ecosystems whose plants rapidly convert solar energy to biomass have high net primary
productive (e.g. tropical jungle)
Nutrients
• Just as energy (nutrients) cycle elements that are essential for life are cycled thorugh biotic and
abiotic system → iogeohemial yles
• Nutrients = elements and compounds required for survival that are consumed by organisms
• Macronutrients = nutrients required in relative large amounts (Nitrogen, carbon, phosphorus)
• Micronutrients = nutrients needed in smaller amounts
Constructing Biogeochemical cycle
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