Interactions with Ecosystems Chapter 2 Grade 7 Science Unit 1 Interactions with Ecosystems Chapter 2

Review: Interactions in the ecosystem 3 types ?? ??? ????

Review: Interactions in the ecosystem 3 types Abiotic – Abiotic Abiotic – Biotic *Biotic - Biotic

Interactions between biotic factors in an ecosystem Symbiosis: Interactions between the biotic parts of the environment. There are 3 types: 1.Parasitism 2.Mutualism 3.Commensalism

1.Parasitism One organism will benefit (the parasite) and the other is harmed (the host).

2.Mutualism Both organism benefit

Commensalism One organism benefits while the other neither gains or loses.

Review: Niche Niche: the organism’s job; what role does the organism play in its environment. It includes: where it lives how it obtains food how it affects its environment

What roles can organisms play?

Different niches: Roles of organisms in the environment 4 major Roles: 1.Producers 2.Consumers 3.Decomposers 4.Scavengers

1.Producers Plants can produce their own food from the abiotic environment. (photosynthesis)

2.Consumers Animals must consume - eat other organisms. (the biotic environment) Can be classified as 3 types herbivores, carnivores, omnivores.

Consumer - Herbivore: Animals that eat ONLY plants (producers).

Consumer - Carnivore: Animals that eat ONLY other animals.

Consumer - Omnivore: Animals that eat both plants AND animals.

3.Decomposers Organisms that break down dead and waste materials into their basic parts.

3.Decomposers cont.. They make chemicals that break apart dead organisms and absorb the nutrients for their own use. Examples include bacteria and other microorganisms, fungi and worms.

4.Scavengers Animals that eat decaying animals and waste materials. Examples include vultures, dung beetle larvae, houseflies, crows and some gulls.

Food chains The transfer of energy from organism to organism. Arrows show the direction of energy flow. Green plants are the food (energy) source for all consumers and decomposers.

Energy Flow **direction of arrows represents energy flow

Make Your Own Food Chain! Label the organisms as producer, decomposer, scavenger, consumer-herbivore, consumer-carnivore, consumer-omnivore

Food chain activity Pick a card find the other members of their chain. Place yourselves in the correct position within the chain. Copy down your food chain Could any changes be made?

“Without plants, no living organisms could exist” Journal entry Respond to the following in paragraph form: “Without plants, no living organisms could exist”

Food webs Interconnecting food chains. Food webs can be VERY complex

Identify the relationships and individual food chains in each:

Living food web activity Pick an ecosystem Every student pick an organism Give one student an end to the string. Where does the chain go from here? Pass the ball of string to everyone involved in the ecosystem How many connections are there?

Food chain to Web activity In groups of two or three, create a food chain using index cards. Write a name and draw a picture on each of your cards. Connect each organism with a string by placing holes in the cards. When every group is done connect all food chains created to form one large food web.

Energy in food webs Many producers are usually required to provide the energy/food required for a small number of consumers

Where do each of the following get energy? Producers? Herbivores? Carnivores? Decomposers?

Where do each of the following get energy? Producers get energy from the sun Herbivores get their energy from consuming plants/producers Carnivores get their energy from consuming herbivores. At the end of the food chain Decomposers get energy from consuming waste or waste products.

Energy Pyramid Is a diagram to show how energy moves and transfers through an ecosystem.

Activity Using the following simple food chain: plants -->mouse--> snake--> Hawk construct a pyramid to illustrate an energy pyramid

plants -->mouse--> snake--> Hawk Where is most of the energy? Where does the rest of the energy go?

Where does the missing energy go? Not all energy gets transferred The “missing energy” has been used for living functions such as: growth, movement, reproduction lost as heat

Journal entry In paragraph form: From what we have just discussed, why would some people say the following? “All flesh is grass”

Nutrient Cycle Nutrients, such as nitrogen and carbon, are recycled in the environment. All organisms are eventually recycled and their nutrients are returned to the soil by the action of decomposers.

The role of decomposers Decomposers, such as bacteria and fungi do much of the recycling in nutrient cycles