Ecology:
❏ Biosphere, atmosphere, lithosphere, hydrosphere
Biosphere is a location where life can exist because is contains the atmosphere, lithosphere, and
hydrosphere. All conditions are required from the three spheres to maintain an ecosystem.
Lithosphere is the rocky outer shell of Earth. It consists of all the rocks and minerals, and makes up
the entire solid landscape of the Earth. Has 50-500 km in thickness.
Atmosphere is the layer of gases surrounding the Earth. Is consists of 78% nitrogen, 21% oxygen, and
1% of other gases. It is critical to life on Earth because it moderates the surface temperature and block
radiation.
Hydrosphere is all the water on, below, and above Earth’s surface. The water can be in any form, such
as water (liquid), water vapour, ice, groundwater ect.
❏ Abiotic and biotic factors
Abiotic factors are non-living components in an ecosystem. Factors such as water, soil, temperature,
light, and nutrients are very important to the ecosystem’s sustainability.
Biotic factors are living components in an ecosystem and the the products of their activities. This can
include plants, animals, their remains,m a bird’s nest ect. They have many types of relationships.
- Competition: individuals compete for limited resources
- Intraspecific competition - between individuals of the same species
- Interspecific competition - between individuals of different species
- Symbiosis: two different organisms associate with each other in a close way
- Mutualism - both benefit from relationship (+, +)
- Commensalism - one benefits, one is unaffected (+, 0)
- Parasitism/Predation - one benefits, one is harmed (+, -)
- Competition - neither are benefited, harmed (-, -)
- Neutralism - both unaffected (0, 0)
❏ Photosynthesis and cellular respiration
Photosynthesis:
(need light energy)
carbon dioxide + water = oxygen + glucose
Cellular respiration:
oxygen + glucose = carbon dioxide + water
❏ Flow of energy in a food chain
When the next trophic level eats the lower one, only 10% of the energy passes on. E.g. if the plant has
200 J of energy, the organism that eats it will get 20 J of energy. The organism that eats that, will get
2 J of energy and so on (200 J, 20 J, 2 J, 0.2 J, 0.02 J…)
❏ Advantages and disadvantages of ecological pyramids
❏ Water cycle
Evaporation: water in the form of water vapour goes into the atmosphere
, Condensation: water vapour turns back into water
Precipitation: water returns to the surface in the form of rain, hail, snow…
Percolation/Infiltration: water goes into the ground or creates surface runoff
Groundwater: water that has been absorbed into the ground
Transpiration: groundwater is taken in by roots and released into the atmosphere in the form of water
vapour
Surface runoff: water that cannot be absorbed by the ground and runs back into bodies of water
❏ Carbon cycle
Carbon dioxide is used in photosynthesis in plants
Cellular respiration occurs in plants, animals, and decomposers so carbon dioxide is released back
into the atmosphere
Plants are either eaten by animals who die and are decomposed by decomposers or die themselves and
decompose or become fossil fuels
Fossil fuels are burned (combustion) and carbon dioxide is released back into the atmosphere
❏ Density independent factors and density dependent factors
Independent:
- Natural disasters
- Temperature
- Sunlight
- Human activities
- Physical characteristics
- Behaviours
Dependent:
- Competition
- Predation
- Disease
- Parasitism
- Crowding
- Stress
❏ Limiting factors and carrying capacity
Limiting factors affect the carrying capacity because they restrict the populations of species therefore
they cannot grow freely. Limiting factors make the carrying capacity smaller because the resources
are limited in an ecosystem and cannot provide for all the species if there are too many.
❏ Human impacts on limiting factors in terrestrial and aquatic ecosystems
Human activities have lots of impacts on limiting factors
Humans affect the amount of light reaching ecosystems. Clear-cutting can remove the shade and
expose organisms to much more light that may not be good. Or erosion can make the lakes cloudy and
the aquatic plants won’t get light.
Water is affected by creating man made dams, stopping the flow of water can affect water availability
for ecosystems.
Nutrient availability can be affected by farming. Also, too many nutrients can be found in the water
and can create invasive species.
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