Biology Review for Unit 1-2

ECOLOGY AND ECOSYSTEMS

FOOD CHAINSOriginal source of energy for most chains is the sun

1st trophic level is producer

2nd trophic level is primary consumer

2rd trophic level is secondary consumer

Decomposer not shown on chain, but they recycle nutrients

Energy is “lost” as you mover “up” the food chain

SYMBIOSIS

PREDATION– Predator EATS Prey– The populations cycle– Predator has lower curve

– There can’t be more predators than prey

POPULATION GROWTH

EXPONENTIAL GROWTH – LOGISTIC GROWTH

J-curveOccurs when unlimited resources are available

S-curveOccurs because resources are limitedCarrying capacity reached

HUMAN POPULATION GROWTH

Overpopulation of humans leads to

– Destruction of habitats (pollution and/or destroying)

– Loss of biodiversity– Introduced species

–Outcompete nativespecies