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Ecology
Ecology: Branch of biology that studies the relationships between a species and their
environment and tries to make sense of them
Population: Is a group of organisms of one species, living in the same area at the same
time
Community: All the different populations of different species living in the same area
Habitat: Is the place where living organisms live
Ecosystem: Is the community of organisms and the habitat they live in

Investigating Population Size using Quadrats:
- A quadrat is a square frame of wire that may be divided up into smaller squares
- When using a quadrat:
• It should be placed randomly, so that a representative sample is taken
...
g
...
They are called
herbivores
Secondary Consumers: These organisms feed on the primary consumers
...
These are
mostly types of bacteria and fungi

Food chains:
- A food chain shows what eats what in a particular habitat
• Food chains show the flow of energy from one trophic level to the next,
starting with a producer
• Sunlight, continually adds energy to the start of the food chain
- Example of a food chain:
• Grass
Field Mouse
Owl

Food Web:
- A food web is a network of connected food chains
• Food webs are more realistic depictions of feeding relationships
• An organism rarely relies on one food source
• Food webs shows interdependence, this is how a change in the population of
one species can affect other species
- Example of a food web:

Hawk
Snake

Rabbit

Mouse

Wildflowers

Grass

Pyramids of Number:
- Food chains can be visualized in pyramids
- Pyramids of number show the number of organisms at each trophic level
• The length of each box indicates how many individuals are present in a
population
- Not all pyramids of number are pyramid shaped (
)
• In some cases, the number of primary consumers (insects) may be higher then
the producer (a tree) (
)

Pyramids of Biomass:
- Biomass is dry organic matter
• Biomass is the mass of the organism without water
- Pyramids of biomass show the biomass of organisms at each trophic level
- All pyramids of biomass are pyramid shaped (
)
• Mass must decrease as we go up the food chain

Pyramids of Energy:
- Pyramids of energy show the amount of energy stored in organisms at each trophic
level
• Some energy is transferred from one trophic level to the next during feeding
- All pyramids of energy are pyramid shaped (
)
• Energy must decrease as we go up the food chain

Energy through food:
- Sunlight is the original source of energy for the food chain
• Producers convert sunlight into chemical energy during photosynthesis
- Other organisms then consume this chemical energy by eating

Energy Losses:
- Energy is lost between trophic levels
• Only around 10% of the energy is passed onto the next trophic level

Energy Losses:
From Sun to Producer
From Consumer to
Consumer

Reasoning:
Not all sunlight hits the chloroplasts, some light is
converted to heat during photosynthesis
Not all parts of the organisms are consumed, not all parts
are digestible, lots of energy lost as heat from respiration



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