Download Chapter 21 Populations and Communities

Chapter 21
Populations and Communities
Ecology is the study of how
living things interact with
each other and with their
environment.
Habitat is environment that
provides living things with
the organisms it needs to live,
grow, and reproduce.
Biotic factors are the living
parts of the habitat.
Abiotic factors are the
nonliving parts of an
organism’s habitat. (Ex:
sunlight, water, oxygen,
temperature and soil).
Species is a group of
organisms that are physically
similar and can mate with
each other and produce
offspring that can also mate
and reproduce.
Population – all the
members of one species in a
particular area. (Ex: pigeons
in NYC, bees in a hive).
Community – all the
different populations that live
together in an area.
Ecosystem is the community
of organisms that live in a
particular area, along with
their nonliving surroundings.
See organization p.709.
NICHE – role of an
organism in its habitat, or
how it makes its living.
Three type of interaction
among organisms:
1. Competition is the
struggle between
organisms to survive.
2. Predation is the
interaction in which one
organism kills another for
food.
3. Symbiosis is a close
relationship between two
species that benefits at
least one of the species.
There are three types of
symbiotic relationships:
1. Mutualism – a
relationship in which both
species benefit.
2. Commensalisms – a
relationship in which one
species benefits and the
other is neither helped nor
harmed.
3. Parasitism is when an
organism lives on or inside
another organism.
PARASITE benefits and a
HOST is what the
organism it lives off.
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