2.1 Energy Flow in Ecosystems - Student Notes
• ______is the total mass of all living things in a given area. (measured in g/m2 or kg/m2)
• Organisms interact with the ecosystem by:
- Obtaining ______from the ecosystem
- Contributing ______to the ecosystem
• Plants are called ______because they make ______during photosynthesis.
CO2 + H2O + sunlight ® C6H12O6 + O2
• ______get their energy by feeding on producers or other consumers.
• ______break-down wastes & dead organisms, through the process of biodegradation.
Energy Flow and Energy Loss in Ecosystems
• Methods to represent ______moving through ecosystems.
– ______: show the flow of energy in an ecosystem.
– ______: represent interconnected food chains. They model the feeding relationships in an ecosystem
– ______: show the changes in available energy from one trophic level to another in a food chain. They’re also called ecological pyramids
Food Chains
• Each step is a trophic level
– ______ = 1st trophic level
– ______ = 2nd trophic level
– ______ = 3rd trophic level
– ______ = 4th trophic level
• Consumers in a food chain can be classified as:
- ______- obtain energy & nutrients from dead organisms & waste matter.
w they have their own, separate food chains & they feed on every trophic level.
w Eg. small insects, earthworms, bacteria & fungi
- ______- primary consumers
w eat plants (producers) only
w Ex. Horse eating hay
3. ______- secondary or tertiary consumers
· ______consumers eat non-producers (herbivores)
Eg. Frog eating a grasshopper
· ______consumers eat secondary consumers
- also called top predators, top carnivores or top consumers
Eg. Lions eating humans
4. ______- consumers that eat both plants & animals
Eg. include humans and bears
Food Webs
• Most organisms are part of many food chains.
– Arrows in a ______represent the ______and nutrients.
– Following the arrows leads to the top carnivore(s).
Food Pyramids
• Energy enters at the first tropic level (producers), where there is a large amount of ______& therefore a lot of energy
• It takes large quantities of organisms in one tropic level to meet the energy needs of the next trophic level.
• 80% - 90% of energy taken in by consumers is used in chemical reactions in the body, or is lost as heat energy.
• The amount of life an ecosystem can sustain is based on the bottom level of the ecological pyramid, where producers capture energy from the sun.
• ______have much larger populations than ______.
• This shows the importance of maintaining large, ______populations at the lowest levels of the food pyramid.