Vocabulary: Photosynthesis, Chemosynthesis Food Chain Food Web Energy Pyramid

 Unlike water and carbon, energy does not cycle through ecosystems.  Energy flows in one direction through an ecosystem because it does not return to the Sun.  All life's functions require energy!

 Energy begins with the sun, and moves from one organism to another when they eat one another (it does not return to the sun)

 Sometimes organisms change energy into different forms.  Not all the energy an organism gets is used for life processes. Some is released to the environment as thermal energy. As a result, the amount of energy that gets passed on is less than what was originally obtained.  Energy can change form as it moves through an ecosystem, but the total amount of energy remains the same. This rule is called the law of conservation of energy.

 Producers  Consumers  Detritvors (decomposers)

 Organisms that make their own food from materials found in their environments are producers.  The process of photosynthesis uses light energy to make food and oxygen from carbon dioxide and water. Sunlight + Water + Carbon Dioxide  Glucose + Oxygen  Chemosynthesis makes food using chemical energy instead of light energy. Ex) Some bacteria on the deep ocean floor use inorganic compounds and the hot water at hydrothermal vents to produce food. Ex) Grasses, trees, plants, and algae are photo- synthetic.

 Consumers obtain energy by eating other organisms.  They are classified by the type of food they eat.  An herbivore eats only plants (ex: deer)  Carnivores are animals that eat other animals (ex: predators such as lions and wolves)  Omnivores eat producers (plants) and consumers (animals). (ex: a bird that eats berries and insects)

 Detritvores eat dead organisms. Ex) insects, voltures, fungus, etc.  Decomposers are detritvores that feed on dead organisms and help break them down.  Decomposers like bacteria and mushrooms help cycle nutrients through ecosystems (releasing CO 2 and decayed matter into soil)  Without them, wastes in the ecosystem would pile up and overwhelm living things

 A food chain is a model that shows how energy flows in an ecosystem through feeding relationships.  In a food chain, arrows show the transfer of energy.  Remember that energy does not cycle through ecosystems because some energy is used for life processes and given off as thermal energy. Therefore, the amount of available energy decreases every time it is transferred from one organism to another.

Note: Primary Consumers: eat producers Secondary consumers: eat primary consumers Tertiary consumers: eat secondary consumers

 Food chains are helpful when studying certain parts of an ecosystem, but it does not show the whole picture.  They do not explain how organisms can have multiple food sources and/or be eaten by multiple predators. The mouse might also eat the seeds of several producers, such as corn, berries, or grass. The snake might eat other organisms such as frogs, crickets, lizards, or earthworms. The hawk hunts mice, squirrels, rabbits, and fish, as well as snakes.

 Scientists use a model of energy transfer called a food web to more accurately depict an ecosystem.  When you overlap the food chains in an ecosystem, the result is a food web.  Food webs show how food chains in a community are interconnected and how energy flows.  Some organisms in a food web might be part of more than one food chain in that web

 Food chains and food webs show how energy moves in an ecosystem, but they do not show how the amount of energy in an ecosystem changes.  An energy pyramid shows the amount of energy available in each step of a food chain.  The steps of this energy model are called trophic levels.  The bottom layer of an energy pyramid contains producers (plants).  The middle layer of an energy pyramid contains consumers that eat producers( herbivores), such as squirrels.  The top layer of an energy pyramid contains consumers that eat other consumers (carnivores/omnivores), such as hawks.

 Only about 10 percent of the energy in one step of an energy pyramid transfers to the next higher step because during life processes, some energy is changed to thermal energy and is transferred to the environment.

The most energy is available at the producer level. There is less energy at each higher level than the level below it. Organisms at each level use some of the energy to carry out their life processes.

 Food chain and energy pyramid Food chain and energy pyramid  BrainPop - energy pyramid BrainPop - energy pyramid  BrainPop food chain BrainPop food chain

IDENTIFY THE: 1. Producers 2. Primary Consumers 3. Secondary Consumers 4. Herbivores 5. Carnivores 6. Omnivores 7. What elements are missing from this food web?