Science 10 – Section 2.1 Notes
Energy Flow in Ecosystems
Biomass = Total mass of all living things in a given area.
- Expressed in g/m2 or kg/m2.
1.
Energy Flow – Organism interacts with ecosystem by:
• Obtaining food from ecosystem.
• Contributing energy to ecosystem.
2.
Producers = plants
• Produce carbohydrates through photosynthesis.
3.
Consumers
• Get their energy by feeding on producers or other consumers.
4.
Decomposers
• Break down wastes and dead things.
• Biodegradation = breaking down of organic matter by living
organisms such as bacteria.
5.
Food Chain
• Shows flow of energy in an ecosystem.
• Each step is a trophic level.
• Producers = 1st trophic level.
• Primary consumers = 2nd trophic level.
• Secondary consumers = 3rd trophic level.
• Tertiary consumers = 4th trophic level.
Examples of terrestrial and aquatic
food chains
6.
7.
Consumers in a Food Chain
a)
Detrivores
• Obtain energy and nutrients from dead organisms and
waste matter.
• Includes small insects, earthworms, bacteria, fungi.
• Feed at every trophic level.
b)
Herbivores – primary consumers
• Eat plants (producers) only.
c)
Carnivores
• Secondary consumers eat non-producers, such as
herbivores.
• Tertiary consumers (top carnivores, top consumers) eat
secondary consumers.
d)
Omnivores
• Eat both plants and animals.
Food Web
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Models the feeding relationships in an ecosystem.
Represents interconnected food chains.
Arrows represent flow of energy and nutrients.
Arrows lead to the top carnivore(s).
8.
Food Pyramids (Ecological Pyramids)
• Shows changes in energy, biomass, or numbers of organisms
from one trophic level to another.
• Large quantities of biomass at one trophic level to meet the
energy needs of the next trophic level.
- Each level loses large amounts of energy (~90%)
through processes of living; energy lost as heat.
• Lower trophic levels have larger populations/more biomass than
upper levels.
Summary