Download Chapter 2 - Holden R

Biology Chapter 2
Principles of Ecology
2.1 Organisms & Their
Environment
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Ecology-the study of interactions that take
place between organisms and their
environment
Biosphere- the portion of earth that supports
living things
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It starts at the bottom of the oceans and extends
high into the atmosphere
It includes all parts of the environment, both living
and non-living
2.1 Organisms & Their
Environment

The environment has 2 types of factors:

Biotic- living parts of the environment
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Abiotic- non-living parts of the environment
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Includes plants and animals
Includes rocks, soil, rainfall, temperature, etc.
You cannot study an organism without
studying both the abiotic and biotic factors
that affect that organism
2.1 Organisms & Their
Environment

The living world has been organized into 4 levels in
order to better understand the interactions
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Organism-this is the actual plant or animal by itself
 For example: a rabbit
Populations- a group of organisms, all the same species,
which interbreed and live in the same area at the same
time
 For example: the rabbits in Holden
Communities- composed of multiple populations in an area
at the same time
 For example: the rabbits and squirrels and birds and people
in Holden
Ecosystems- includes the interacting of communities and
their abiotic factors
 For example: the rabbits, squirrels, birds, people and soil,
houses, climate, roads, etc. in Holden
2.1 Organisms & Their
Environment

Habitat- the place where an organism lives out its
life
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For example: your dog’s habitat includes the
backyard, and maybe the front yard and house,
possibly a dog house
Niche- the role or position a species has in its
environment
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For example: your dog’s niche may be to eat dog food,
sleep on the couch, play in the backyard and provide
you with unconditional love
Species can occupy the same habitat, but they cannot
occupy the same niche
2.1 Organisms & Their
Environment

Symbiosis- a close, permanent relationship between
2 species
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Commensalism- one species benefits and the other
species is not hurt or helped
 Mosses or ferns grow on larger plants, which provide a
habitat, but are not damaged
Parasitism- one species benefits and the other is harmed
 For example: ticks benefit by gaining food and dogs can be
harmed by diseases carried by ticks
Mutualism- both species benefit
 For example: ants and acacia trees-the ants receive shelter
and food, the trees receive protection from being eaten
2.2 Nutrition & Energy Flow

Autotrophs- use the sun’s energy to make
their own food
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Also called producers
Includes plants and algae
Plants make food through photosynthesis
Heterotrophs- consume other organisms for
food
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
Can eat only autotrophs, only other heterotrophs,
or both autotrophs & heterotrophs
Examples include deer, owls, humans
2.2 Nutrition & Energy Flow

Heterotrophs are further classified:

Herbivores- eat only plants
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Carnivores- eat only animals
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Examples: lions, sea otters
Carnivores include scavengers, who eat only dead
animals for food, such as vultures
Omnivores- eat both plants and animals

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Examples: deer, cows, caterpillars
Examples: humans, bears, raccoons, bass
Decomposers- break down dead organisms and
release their nutrients back to the environment

Examples: bacteria and fungi
2.2 Nutrition & Energy Flow

Matter and energy is transferred among organisms
based on who eats what
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This is called a food chain
Food chains show feeding relationships in a single
chain of trophic levels as follows:
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Producer- plants
1st order consumer- animal that eats the plant
2nd order consumer- animal that eats the 1st order
consumer
3rd order consumer- animal that eats the 2nd order
consumer
Decomposers-break down all of the above after they die
2.2 Nutrition & Energy Flow

Food Webs- food webs show multiple feeding
connections among organisms in an
ecosystem
2.2 Nutrition & Energy Flow

Ecological Pyramids- show graphically the quantities
of matter and energy transferred between trophic
levels
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The standard rule is that 10% of the biomass or energy
from one trophic level is transferred to the next trophic level
The lost energy or biomass is “burned” off as heat or growth
2.2 Cycles in Nature

There is a constant amount of matter in the
universe at all times


This matter is constantly being recycled and
reused
Four examples of nutrient cycling:
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Water Cycle
Carbon Cycle
Nitrogen Cycle
Phosphorus Cycle
2.2 Cycles in Nature

Water Cycle
It then condenses in
the clouds
surface water
(oceans, lakes,
streams) evaporates
into the atmosphere
When enough water
is in the clouds, it
falls as precipitation,
such as rain, snow,
or ice
It then runs back into
the surface water, or
gets absorbed into
the ground water
2.2 Cycles in Nature

Carbon Cycle: carbon cycles, but can also be
stored in the atmosphere and oceans for
extended periods of time
Producers and
consumers release
carbon dioxide into
the atmosphere
through respiration
Dead and
decaying
organisms form
fossil fuels over
time
Producers absorb
carbon dioxide from
the atmosphere
through
photosynthesis
Consumers eat the
producers and
absorb the carbon
2.2 Cycles in Nature

Nitrogen Cycle: 78% of atmosphere is
nitrogen
Certain bacteria release
Urine from organisms or
decay from dead
organisms return
nitrogen to the soil or the
atmosphere
Herbivores eat the
plants and convert
the nitrogen to animal
proteins
nitrogen from the soil
back to the atmosphere
Bacteria in the soil
“fix” nitrogen from
the air into the soil
Plants use the
nitrogen in the
soil to make
proteins
2.2 Cycles in Nature

Phosphorus Cycle
Plants use phosphorus
from the soil
Rain washes
phosphates
from soil
Phosphates leach
from soil into
streams
Plants
die
Soil decomposers
act on plant and
animal waste to
release phosphorus
SHORT TERM
Phosphate
weathers
from rocks
into streams
Geologic
processes
raise
phosphate
Phosphates
rocks to
settle and get surface
trapped in rocks
at the bottom of
streams LONG TERM