Biology SL – Class Notes.

Biology SL – Class Notes

4.1 Species, communities and ecosystems

E.I: The continued survival of living organisms including humans depends on suitable conditions.

C.1: Species & Communities

E.I: Community structure is an emergent property of an ecosystem.

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• Niche: each species play a unique role within a community because of the unique combination of its spatial habitat and interaction with other species.
• Competitive exclusion: specie out competes the other.
• Keystone species: such species are described as playing a critical role in maintaining the structure of an ecological community, affecting many other organisms in an ecosystem.
• Inorganic factors: this is important in the community because organic organisms depend on these molecules (Carbon, Oxygen, Hydrogen and Nitrogen) for their growth
• Autotrophs: Produce their own food
• Heterotrophs: Get the food from other organisms
• Sustainability: nutrient availability. Detox of waste products.

4.2 Energy Flow

E.I: Ecosystems require continuous supply of energy to fuel life process and to replace energy lost as heat.

C.2 Communities and Ecosystems

E.I: Changes in a community structure affect and are affected by organisms

[pic 1]

• Flow of energy: energy comes from the sun, producers transform the energy and produce food for the consumers. Consumers then change and animals eat each other.
• Sun (light) > Plants do Photosynthesis and convert light energy into chemical > primary consumers turn chemical energy into ATP
• Energy is lost in between each trophic level.

4.3 Carbon cycle

E.I: Continued availability of carbon in ecosystems depend on carbon cycling

• Flux: Changing carbon from one form to another [pic 2]
• Absorption of carbon dioxide: Carbon dioxide diffuses into autotrophs through photosynthesis.
• Methane can be produced by mammals and is oxidized into carbon molecules.
• Peat is made of dead organisms that need to be pressed and heated to form the basic fossil fuels.[pic 3]
• Combustion the product is carbon dioxide and when is not fully exploited it turns into mono.
• Mostly all organic materials can be used to be combusted.
• Limestone: calcium carbonate: organisms that have a lot of calcium in their bodies become carbonated (fossilized)

E.I: Changes in community structures affect and are affected by organisms

• Greenhouse gases: Carbon dioxide and vapour and methane and nitrogen
• Greenhouse gases can absorb heat and retain radiation
• Concentration of a gas and its ability of absorb long wave radiation
• Respiration and combustion add Co2 into de atmosphere
• Photosynthesis absorbs water
• Evaporation and transpiration add water into the atmosphere
• Precipitation absorbs water from the atmosphere
• Fraking and extracting fossil fuels add methane into the atmosphere
• Bacteria agriculture and vehicles produce nitrous oxide
• What makes a greenhouse gas a greenhouse gas? It retains heat (long wave radiation)
• The atmosphere absorbs about 20 – 25 % of the heat that comes from the sun
• The rest reaches the earth, most is converted into heat and the rest bounces back
• The industrial revolution is the perfect example of pollution and climate change due to the new amounts of carbon in the air

C3 Impacts of humans on ecosystems

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