Energy in an Ecosystem Science 10

Capturing Energy From the Sun All living organisms require energy in order to support life All living organisms require energy in order to support life The only source of energy available to the Earth comes from the Sun The only source of energy available to the Earth comes from the Sun Therefore, this energy must be captured by some organisms in order to power life on Earth Therefore, this energy must be captured by some organisms in order to power life on Earth

Ecosystem An ecosystem describes all of the organisms within a given area and how they interact with their environment and each other An ecosystem describes all of the organisms within a given area and how they interact with their environment and each other We could consider an ecosystem as large as the Earth or as small as a fish tank depending on the scale we wish to investigate We could consider an ecosystem as large as the Earth or as small as a fish tank depending on the scale we wish to investigate

Energy From the Sun Energy from the sun is captured by green plants through the process of photosynthesis Energy from the sun is captured by green plants through the process of photosynthesis Plants are able to take water from the Earth and carbon dioxide from the atmosphere and combine them to form sugar and release oxygen Plants are able to take water from the Earth and carbon dioxide from the atmosphere and combine them to form sugar and release oxygen This process requires sunlight and chlorophyll This process requires sunlight and chlorophyll

Producers Any organism that is able to produce its own food is called a producer Any organism that is able to produce its own food is called a producer Producers are able to capture energy from the sun through photosynthesis Producers are able to capture energy from the sun through photosynthesis This energy will be stored in chemical compounds within the plant This energy will be stored in chemical compounds within the plant

Primary Consumers Primary Consumers are organisms that get the majority of their energy from producers Primary Consumers are organisms that get the majority of their energy from producers They are called herbivores They are called herbivores Examples would be deer, rabbits and cows Examples would be deer, rabbits and cows

Secondary Consumers Secondary Consumers are organisms that feed primarily on primary consumers Secondary Consumers are organisms that feed primarily on primary consumers They are called carnivores They are called carnivores Examples would be coyotes, bobcats and spiders Examples would be coyotes, bobcats and spiders

Tertiary Consumers Tertiary Consumers are those who would feed primarily on secondary consumers Tertiary Consumers are those who would feed primarily on secondary consumers They are called top carnivores They are called top carnivores Examples would be polar bears and eagles Examples would be polar bears and eagles

Activity Complete the “From Land to Mouth” activity on page 6 Complete the “From Land to Mouth” activity on page 6 Complete all five steps of the What to Do Complete all five steps of the What to Do Answer the three What Did You Discover and one Extension question Answer the three What Did You Discover and one Extension question

From Land to Mouth 1. 14:1 2. Lots of variation; due to the amount of the plant that can be consumed and growth rate 3. Plants; more energy per given area 4. Comparison a)Rice – 507m^2 b)Chicken – 3300m^2

Trophic Levels When we consider an ecosystem, it is often useful to consider the trophic (or feeding) levels within the ecosystem When we consider an ecosystem, it is often useful to consider the trophic (or feeding) levels within the ecosystem Most ecosystems would have four trophic levels although more are possible Most ecosystems would have four trophic levels although more are possible

Trophic Levels First Trophic Level – Producers First Trophic Level – Producers Second Trophic Level – Primary Consumers Second Trophic Level – Primary Consumers Third Trophic Level – Secondary Consumers Third Trophic Level – Secondary Consumers Fourth Trophic Level – Tertiary Consumers Fourth Trophic Level – Tertiary Consumers

Energy Loss 10% Rule 10% Rule This rule states that for each trophic level, there will be approximately 10% of the energy available to the next trophic levelThis rule states that for each trophic level, there will be approximately 10% of the energy available to the next trophic level For example For example Sun’s Energy – 1000JSun’s Energy – 1000J Grass – 10JGrass – 10J Deer – 1JDeer – 1J Lion –.1JLion –.1J

Pyramid of Numbers Since each trophic level has less energy available than the previous level, the population normally decreases as the trophic level increases Since each trophic level has less energy available than the previous level, the population normally decreases as the trophic level increases So for an ecosystem with plants, there may only be 2 tertiary consumers So for an ecosystem with plants, there may only be 2 tertiary consumers

Pyramid of Biomass In some cases the pyramid of numbers won’t work; for instance if you have a very large producer compared to the size of primary consumers In some cases the pyramid of numbers won’t work; for instance if you have a very large producer compared to the size of primary consumers This is most evident in the life that can be supported by a tree; one tree may support millions of insects This is most evident in the life that can be supported by a tree; one tree may support millions of insects In this case, a pyramid of biomass is more useful to consider In this case, a pyramid of biomass is more useful to consider

Food Web We can use a web to indicate all of the organisms within an ecosystem as opposed to using a pyramid or food chain We can use a web to indicate all of the organisms within an ecosystem as opposed to using a pyramid or food chain

Ecosystem Activity Take 20 minutes and walk through the Urban Wilderness Park Take 20 minutes and walk through the Urban Wilderness Park Identify as many living organisms as possible Identify as many living organisms as possible Classify the organisms by trophic level; you can include them in different levels if appropriate Classify the organisms by trophic level; you can include them in different levels if appropriate Create a Urban Wilderness Park food web Create a Urban Wilderness Park food web

Questions Page 7 Page Page 17 Page