Biotic Factors: Living Parts of the Ecosystem (Ex: Trees, Birds, Etc.)

Ecosystems Review

Biotic factors: living parts of the ecosystem (ex: trees, birds, etc.)

Abiotic factors: non-living parts of the ecosystem (ex: rocks, water, etc.)

Population  Community  Ecosystem

Population: group of organisms of the same species living together

Community: groups of populations living in the same area

Ecosystems: community + all the non-living surroundings

Predator-Prey:

Predators feed on other organisms.

Prey are the organisms that get eaten.

The prey population needs to be larger than the predator population. As the prey population increases, the predator population increases. If the prey population decreases, the predator population decreases.

Predation keeps population size within the limits of available resources.

Symbiosis: means “living together”; there are 3 types of symbiotic relationships

1. Parasitism: the host is harmed and the parasite benefits (ex: human and a tapeworm)

Host Parasite

1. Commensalism: one organism is not harmed nor benefited and the other organism benefits (ex: tree and a bird)

Organism Organism
Unaffected Benefitted
______

1. Mutualism: both organisms benefit (ex: clown fish and an anemone)

Organism Organism
Benefitted Benefitted

Food Chain: represents the flow of energy in an ecosystem; the arrows represent the direction of energy flow and are called trophic levels, there are usually 3-4 trophic levels in a food chain, but no more than 5 levels

Grass  Insect  Bird  Hawk

Producer: organisms that undergo photosynthesis (grass); these are also called

autotrophs

Consumer: organisms that must eat producers/consumers; these are also called

Heterotrophs

Primary consumer: these organisms eat the producers (insect)

Secondary consumer: these organisms eat the primary consumers (bird)

Tertiary consumer: these organisms eat the secondary consumers (hawk)

Scavengers:organisms that feed on dead animals (ex: vultures)

Decomposers:organisms that break down dead organic material (ex: fungi)

Herbivores:eat only producers

Carnivores:eat only consumers

Omnivores:eat producers and consumers

Food Webs:interconnected food chains

`

Food chain 1: seeds  chipmunk  grizzly bear

Food chain 2: berries  chipmunk  goshawk

Pyramids:

Energy Pyramid

Only 10% of the energy

from one trophic level

is used by the next level.

The rest of the energy is lost as heat.

Number PyramidBiomass Pyramid

There must always be more prey than predators because the predators can not use all the energy that is consumed from the prey. The lower an organism is on the food chain, the higher the numbers of these organisms. The more organisms there are at a trophic level, the more mass the group of organisms has.

Biological Magnification:

If a chemical or toxin (ex: DDT) enters the food chain at a low level (ex: grass) the amount of that chemical increases as you move up the food chain.

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