Interactions of Living Things 7th Grade Science

PART 1

Biotic vs. Abiotic -Biotic – all LIVING parts of environment. -ex: tree, fly, people -Abiotic – all NONLIVING parts of environment. -ex: water, soil, sunlight, temp.

Levels of Environmental Organization Organism Population – all same species that live in area Community – all species that live in area Ecosystem – community plus abiotic factors 5. Biosphere – all ecosystems, anywhere life exists

Salt Marsh – page 6 -What are some biotic factors in this marsh? *cordgrass *jellyfish *egret *heron *algae *marsh crab -What are some abiotic factors? *water *sunlight *soil *temperature

PART 2 LIVING THINGS NEED ENERGY

Players in the Energy Game -Producers – use sunlight to make food -ex: plants, algae -Consumers – eat other organisms -herbivore – eats only plants -omnivore – eats both plants & animals -carnivore – eats only animals -scavenger – eats dead plants & animals

-Decomposers – get energy by breaking down dead organisms -ex: bacteria & fungi -called nature’s recyclers

Food Chains -Diagram that shows energy flow from one organism to another -Why are these rare in nature?

Food Webs -More realistic than chains -Interconnected chains show feeding relationships in ecosystem -Arrows – is eaten by

Energy Pyramids -diagram that shows loss of energy as it passes through food chains Amount of energy decreases as you move up the levels Amount of toxins increase as you move up the levels

PART 3 TYPES OF INTERACTIONS

Limiting Factors -Scarce resource that limits size population can grow -ex: food becomes a limiting factor when population outgrows amount of food available

Carrying Capacity -Largest population an environment can support at any given time -When a population grows larger than carrying capacity, limiting factors cause individuals to die or leave

Competition -2 or more individuals or populations trying to use the same resource.

Predators vs. Prey -Predator – organism that eats the prey -wide variety of methods & abilities for getting food A cheetah’s speed gives it an advantage over other predators competing for the same prey

Prey Adaptations -Prey have methods to keep from being eaten: 1. stay in groups 2. camouflage 3. defense (poison, chemical, physical) 4. burrowing

Stay in groups or Herds

Camouflage

Defense

Warning Coloration

Symbiosis -Close, long-term association between members of 2 or more species -classified as one of the following: 1. mutualism 2. commensalism 3. parasitism

Mutualism -Both organisms benefit from the interaction. -ex: you & e.coli in your stomach!!!

Commensalism -One organism benefits, the other is unaffected. -ex: sharks & remoras

Parasitism -One organism benefits, the other is harmed. -organism that benefits - parasite -organism harmed - host -ex: Caterpillar & Wasp eggs