1. FLOW OF ENERGY
Unit 6: Life science

2. Explain where all the energy in an ecosystem comes from.
Classify organisms according of how they obtain their energy and give examples of them.
Be able to draw and interpret a food web.
Explain the flow of energy through an ecosystem using an energy pyramid.
LESSON OBJECTIVES:

3. Checking your understanding:
What is photosynthesis?
What are some organisms that can photosynthesize?
What is a community?
Checking your understanding:

4. Energy is the ability to do work
Energy is the ability to do work. In organisms, this work is physical work like walking and jumping.
It can also be the work used to carry out the chemical processes in their bodies.
All organisms need a supply of energy to stay alive.
Some organisms can get their energy from the sun.
Other organisms get their energy from other organisms.
Through prey-predator relationships, the energy of one organism is passed on to other organisms.
Energy and Producers:

5. Producers: The survival of an ecosystem is dependent on the producers.
Without producers capturing the energy from the sun and turning it into glucose, an ecosystem could not exist.
On land plants are the dominant producers. Algae also known as phytoplankton are the most common producers I n the ocean.
There are also bacteria that uses chemical processes to produce their own food.
Producers:

6. Organisms that consume other organisms to get food for energy are called consumers. All animals are consumers.
Consumers can be placed into different groups.
Herbivores: animals that eat plants such as rabbits and deer as well as caterpillars.
Carnivores: animals that consume animals like the snake and the eagle.
Omnivores: animals that eat both producers and consumers. People, dogs, bears, raccoons are omnivores.
Decomposers: get nutrients and energy by breaking down dead animals and organisms waste.
Consumers:

7. Decomposers are important:
Besides breaking down dead animals and their waste, decomposers are vital to the maintenance of an ecosystem.
Through their consuming process, decomposers release nutrients such as carbon and nitrogen.
These nutrients are recycled back into the ecosystem so that the producers can use them in their processes of photosynthesis.
The stability of the ecosystem depends on the decomposers.
Decomposers are important:

8. Food Chains and Food Webs:
Food chains show the eating patterns of an ecosystem.
Food energy flows from one organism to another.
Arrows are used to show the feeding relationships between organisms.
The arrows point from the organisms being consume to the animals that eats it.
Food Chains and Food Webs:

9. Food Chains and Food Webs:
The producers are always at the beginning of the food chain. The herbivorous come next, then the carnivores.
Each organism can eat and be eaten by various types of organisms, so simple food chains are rare in nature.
Since feeding relationships are so complicated, we can combine food chains together to create a more accurate flow of energy in an ecosystem; a FOOD WEB.
Food Chains and Food Webs:

10. When the herbivore eats a plant, the energy in the plant tissues is used by the herbivore.
The herbivore uses this energy to power its own life processes and to build more body tissue.
However, only 10% of the total energy from the plant gets stored in the herbivore’s body as extra body tissue.
The rest of the energy is used by the herbivore and released as heat.
ENERGY PYRAMIDS:

11. The next consumer on the food chain that eats the herbivore will store only about 10% of the total energy from the herbivore in its own body.
This means that the carnivore will only store about 1% of the total energy that was originally in the plant.
The majority of the energy is used or released to the environment.
Every time energy is transfer from one organism to another, there is loss of energy.
ENERGY PYRAMIDS:

12. ENERGY PYRAMIDS: Energy loss can be shown in an energy pyramid.
Since there is energy loss in food chains, it takes many producers to support just a few carnivores in a community.
Each step in a food chain in the energy pyramid is called a trophic level.
Plants and other photosynthetic organisms are found in the first trophic level at the bottom of the pyramid. It is followed by primary consumers, then secondary consumers and so on.
Because of the great loss of energy, there are only 4 or 5 trophic levels.
ENERGY PYRAMIDS:

13. Things to consider for our food energy pyramid
1.Shelled animals generally have a calcium carbonate shell. Water that is highly acidic may cause those organisms to lose the ability to grow a shell or they may grow a shell very slowly.
2. Agricultural run-off generally includes remnants of fertilizer used in farming. The fertilizer can trigger a large growth of phytoplankton which can deplete oxygen levels.
Things to consider for our food energy pyramid