An ecological system - consists of a living community and all of the physical aspects of its habitat

- physical factors are known as abiotic factors and can include:

light, temperature, precipitation, soil type, water availability, soil and water pH, etc… - the members of the living community are known as the biotic factors in an ecosystem - the biotic and abiotic factors in an ecosystem influence each other.

Ecosystems rely on energy -The amount of energy available

in an ecosystem determines how many organisms can live in that ecosystem

How does energy enter an ecosystem?

- Sunlight is the primary source of energy for most ecosystems on earth

No sun = No energy No Energy = No Life

No Life = BUMMER!

Sunlight needs to be converted to be used in an ecosystem.

Who converts the sunlight? - plants, algae, some bacteria - organisms that convert the

energy from sunlight into a useable form are known as producers

- How do they do convert the energy? Photosynthesis

Why is it important? - traps the sun’s energy and

stores it in a sugar called glucose. - The stored energy is used by

living things

6 CO2 + 6 H2O + Energy C6H12O6

+ 6 O2Carbon Water Sunlight

Glucose OxygenDioxide

Who uses the energy trapped by producers?

- All living things use the energy trapped

by producers - producers use this energy

themselves - Other living things, called

consumers eat producers for their energy

C6H12O6 + 6O2 6CO2 +

6H2O + Energy Glucose Oxygen Carbon Water ATP Dioxide

Living things break down glucose and the energy stored in it, using a process called cellular respiration

Herbivore – plant eater

Carnivore – animal eater

Omnivore – eats both plants and animals

Photosynthesis 6 CO2 + 6 H2O + Energy C6H12O6 +

6O2

Cellular Respiration C6H12O6 + 6O2 6CO2 + 6H2O + Energy

The two processes are the opposite of each other - the products of one process are the reactants of the other

Divided into Trophic (feeding) levels. Primary producers/autotrophs Primary consumers/herbivores-plant eaters Secondary consumers/carnivores –meat eaters Tertiary consumers/carnivores Detritivores/decomposers- vital part of the

ecosystem. They recycle abiotic materials from dead organisms – without them, life would stop.

- they play a role in nutrient cycling

Primary Consumers

Producers

Detritus Feeders

Producers

Primary Consumers

Secondary Consumers

Tertiary Consumers

Decomposers

90% of the energy available is lost as energy is transferred to the next trophic level - the energy is lost as heat Only 10% is of passed on to the next level

100,000 J of sunlight

100 J Rats

10 J Snakes

1,000 J Grasshoppers

10,000 J wheat

Food Chain – the path of

energy through the trophic levels of an ecosystem

- all food chains begin

with a producer

= a series of multiple interconnected food chains. - in most ecosystems, energy doesn’t follow a simple path

- many consumers eat at different trophic levels

- food webs are a representation

of the complex relationships between organisms in an ecosystem

Productivity is a measure of the amount of energy available in a ecosystem

Gross Primary Productivity:–a measure of the total energy captured by plants through photosynthesis

Net Primary Productivity=net primary productivity is the energy available to consumers

- the difference between the amount of energy trapped by photosynthesis and the amount

used by the plants through cellular respiration

NPP=GPP-Rs NPP =Net Primary Productivity GPP = Gross Primary Productivity

-the total amount of sun’s energy trapped and converted into useable form

by photosynthesis Rs= Plant Respiration : - the amount of energy consumed by the

plant for its own needs Net Primary Productivity is important because it

is the energy available to consumers.

12% decline due to deforestationUse 28 % used for food, building

materials, energyTogether 40% of Earth’s NPP is

committed to the use of humans.

Abiotic factors Food ChainBiotic Factors Food WebProducers Gross Primary Productivity Consumers Net Primary ProductivityPhotosynthesis- Definition Photosynthesis – equationCellular Respiration - Definition Cellular respiration-equation Trophic levels Herbivore Carnivore OmnivoreDetritivores/ Decomposers

Energy Flow Questions

1.Most food chains only have 4 levels. Why?

2.Use your knowledge of energy flow through an ecosystem to explain why we could feed more of the Earth’s people by eliminating meat from our diet.

Assuming all primary plant growth was utilized by humans and no other effects (pollution, disease) are taken into account then the theoretical carrying capacity is

100%/40% x 6 billion people=15 billion