1. 2.1 Energy Flow in Ecosystems
Biomass 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 food from the ecosystem
Contributing energy to the ecosystem

3. Energy Flow in Ecosystems
Plants are called producers because they make carbohydrates during photosynthesis.
CO2 + H2O + sunlight  C6H12O6 + O2
Consumers get their energy by feeding on producers or other consumers.
Decomposers are living organisms that
break-down wastes & dead organisms,
through the process of biodegradation.
Decomposition is the breaking down of
organic wastes and dead organisms.

4. Energy Flow & Energy Loss in Ecosystems
Methods to represent energy moving through ecosystems.
Food chains: show the flow of energy in an ecosystem.
Food webs: represent interconnected food chains. They model the feeding relationships in an ecosystem
Food pyramids: show the changes in available energy from one trophic level to another in a food chain. They’re also called ecological pyramids

5. Food Chains 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

6. Provincial Exam Question

7. This dung beetle is a detrivore.
Consumers in a food chain can be classified as:
Detrivores (decomposers) - obtain energy & nutrients from dead organisms & waste matter.
they have their own, separate food chains & they feed on every trophic level.
Eg. small insects, earthworms, bacteria
& fungi
Herbivores - primary consumers
eat plants (producers) only
Ex. Horse eating hay
This dung beetle is a detrivore.

8. 3. Carnivores - secondary or tertiary consumers
Secondary consumers eat non-producers (herbivores)
Eg. Frog eating a grasshopper
Tertiary consumers eat secondary
consumers
also called top predators, top
carnivores or top consumers
Eg. Lions eating humans
4. Omnivores - consumers that eat both
plants & animals
Eg. include humans and bears

9. Provincial Exam Question

10. Food Webs Most organisms are part of many food chains.
Arrows in a food web represent the flow of energy
and nutrients.
Following the arrows leads to the top carnivore(s).

11. Food Pyramids
Energy enters at the first tropic level (producers), where there is a large amount of biomass & therefore a lot of energy.

12. It takes large quantities of organisms in one trophic 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.

13. 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.
This shows the importance of maintaining large, biodiverse
populations at the lowest levels of the food pyramid.
2.1 QUIZ