What is energy?What is energy?
• The energy living things need comes from carbon-compounds, or organic compounds.– Organic compounds: molecules that contain a
carbon atom• Carbohydrates: glucose, starch, cellulose (mostly
plants)• Proteins: the muscles of animals (steak!)• Fats: in muscle of animal tissues (fatty steak!)
Food ChainsFood Chains
• A food chain shows the flow of energy between the organisms in an environment
Food ChainsFood Chains
• Notice that the arrow points from the organism being eaten to the organism that eats it.– Like the burger you eat goes into you
Plants Cow (burger) Human
What do the arrows in the food chain What do the arrows in the food chain below indicate?below indicate?
A. Sunlight
B. Energy flow
C. Heat transfer
D. Toxins
What do the arrows in the food chain What do the arrows in the food chain below indicate?below indicate?
Energy flow
Food WebsFood Webs
• When we put many food chains together in one ecosystem, it is called a food web.
Energy Moves in a Food WebEnergy Moves in a Food Web
Plants make glucose from light
Some animals get energy from plants
Other animals get energy from the fat and protein in other animals
There are two groups that organisms are divided into in any ecosystem based upon how they obtain energy.
----------------- use sunlight directly to make their own food.
Two groups of organisms based on energy consumption.
Producers- use sunlight directly to make their own food.
---------------- Organisms that eat producers or other organisms for energy.
Two groups of organisms based on energy consumption.
Producers- use sunlight directly to make their own food.
Consumers- Organisms that eat producers or other organisms for energy.
Consumers are Divided into Five Categories
• Herbivore consumer that eats plants.
• ---------------- consumer that eats animals.
Consumers are Divided into Five Categories
• Herbivore- consumer that eats plants.
• Carnivore- consumer that eats animals.
• ---------------- consumer that eats both plants and animals.
Consumers are Divided into Five Categories
• Herbivore- consumer that eats plants.
• Carnivore- consumer that eats animals.
• Omnivore consumer that eats both plants and animals.
Consumers are Divided into Five Categories
• ------------------ animals that feed on the bodies of dead animals.
Consumers are Divided into Five Categories
• Scavengers- animals that feed on the bodies of dead animals.
• ____________ - organisms that get their energy by breaking down the remains of dead organisms.
Consumers are Divided into Five Categories
• Scavengers- animals that feed on the bodies of dead animals.
• Decomposers - organisms that get their energy by breaking down the remains of dead organisms.
Decomposers
• Are essential to any ecosystem because they are nature’s recyclers.
Decomposition
Two groups of organisms based on energy consumption.
Producers- use sunlight directly to make their own food.
Consumers- Organisms that eat producers or other organisms for energy.
– Herbivores– Carnivores – Omnivores – Scavengers– Decomposers
Energy PyramidsEnergy Pyramids
Energy Pyramids are diagrams shaped like a triangle that shows the loss of energy at each level of the food chain.
Energy Pyramid
There are typically only 4 trophic levels in an energy pyramid
• Producers: organisms that convert the sun’s energy into organic compounds
• Primary consumers: organisms that eat producers to obtain energy compounds
• Secondary consumers: organisms that eat primary consumers for energy
• Tertiary consumers: organisms that eat secondary consumers for energy
Energy Pyramid LabelsEnergy Pyramid Labels
Producers
Tertiary Consumers
Primary Consumers
Secondary Consumers
• Trophic levels represent a feeding step in the transfer of energy and matter in an ecosystem. Each Trophic Level is the total amount of energy and biomass in all organisms at one level in the food web.
• Biomass- the amount of organic matter (nutrients) comprising a group of organisms in a habitat.
Energy PyramidsEnergy Pyramids
• Only energy stored in tissues of an organism can be transferred to the next level.
• As you move up a food chain, both available energy and biomass decrease.
• Energy and biomass are transferred upwards but are diminished with each transfer. The higher up in the pyramid an organism is, the more they must eat to obtain energy.
More Energy
Less Energy
Energy Transfer (percents)Energy Transfer (percents)
100%
0.1%
10%
1%
• We can say that the energy transfer from level to level is inefficient– (not a lot of the energy
at each level makes it up)
Energy Transfer (calories)Energy Transfer (calories)
1,000 calories
1 calorie
100 calories
10 calories
• This means that there can’t be many levels in a food web or pyramid– The amount of energy
decreases, and it cannot typically support organisms at higher levels than tertiary consumer
Why are there a limited number of energy Why are there a limited number of energy levels in an energy pyramid or food web?levels in an energy pyramid or food web?
A. Energy transfer is very efficient
B. Energy is captured as heat
C. Energy transfer is inefficient
D. Energy is not transferred in a food web
How is energy stored and transferred in How is energy stored and transferred in an ecosystem?an ecosystem?
A. In light
B. In oxygen and carbon dioxide
C. In carbon compounds like glucose
D. In the process of decomposition
Which of the following organisms is a Which of the following organisms is a primary consumer in the ecosystem primary consumer in the ecosystem
shown?shown?
A. Hawk
B. Rabbit
C. Mountain lion
D. Frog
Population Impacts in a Food WebPopulation Impacts in a Food Web
• If the population of organisms at any level of the food web changes, it will affect the population at other levels
Population Impacts in a Food WebPopulation Impacts in a Food Web
• If the population of producers decreases, then the population of primary consumers will decrease if they don’t have enough food.
Population Impacts in a Food WebPopulation Impacts in a Food Web
• If the population of primary consumers decreases, then…– The producers will increase because there are
less consumers eating them– The secondary consumers will decrease
because there is less food for them
Which organism would be most affected if Which organism would be most affected if the cricket population decreased?the cricket population decreased?
A. Snake
B. Deer
C. Frog
D. Hawk
Photosynthesis
• Photosynthesis: a process that occurs in producers and converts light, carbon dioxide, and water into glucose (sugar) and oxygen.
More Photosynthesis
a. Photosynthesis removes carbon dioxide from the air.
b. The carbon dioxide in the air is the building block for glucose.
c. The light energy helps bond CO2 and H2O together to make glucose.
How do consumers get energy?
Consumers eat other organisms to obtain organic molecules, which are forms of stored energy.
During cellular respiration, consumers release the energy stored in the bonds of the organic molecules.
Carbon Cycle
• Carbon is found throughout the environment– Carbon is found in the atmosphere and in
water as carbon dioxide (CO2)
– Carbon is found in organisms as organic molecules, like glucose (sugars) and fats
– Carbon is found buried in the ground as fossil fuels
Carbon Cycle
2) Producers: Use photosynthesis to make sugars from CO2 in the atmosphere (carbon is moved!)
Carbon Cycle
3) Consumers: Eat organic molecules and release CO2 into the atmosphere during respiration, or die and go into the soil
Carbon Cycle
4) Soil: decomposers break down organisms, releasing carbon into the atmosphere OR trapping it in the ground (fossils)
Carbon Cycle
5) Fossil Fuels: carbon from some dead organisms are trapped as fossil fuel until we burn it
1. What do the arrows in the food chain 1. What do the arrows in the food chain below indicate?below indicate?
A. Sunlight
B. Energy flow
C. Heat transfer
D. Toxins
6. Which organism would be most 6. Which organism would be most affected if the cricket population affected if the cricket population
decreased?decreased?
A. Snake
B. Deer
C. Frog
D. Hawk
7. How does energy enter a food chain?
A.The process of cellular respiration
B. The process of photosynthesis
C. Decomposers make the energy
D. None of the above
8. Where do plants get Carbon molecules needed for photosynthesis?
a. From the earthb. From the atmospherec. By breaking down dead organismsd. From the sun
9. An iguana that feeds on cabbage, carrots, crickets, and meal worms as a regular diet would be considered a
A.CarnivoreB.HerbivoreC.OmnivoreD.Decomposer
Food Chains
• Food chains can be misleading because organisms very rarely eat only one other organism.
• Food webs show the many pathways of energy flow.