Chapter 3
Section 1
Interactions & Interdependence
Like all organisms, we interact with
our environment.
Ecology is the scientific study of
interactions among organisms and
their environment.
The word ecology was coined in
1866 by German biologist Ernst
Haeckel.
The biosphere is the entire planet
including land, water, and air.
It extends from about 8 km above
Earth’s surface to as far as 11 km
below the surface of the ocean.
Organisms and their environment
are interdependent in the biosphere.
Levels of Organization
1.) Species- group of organisms
that can breed and produce
offspring.
2.) Populations- groups of
individuals that belong to the same
species and live in the same area.
3.) Communities- groups of different
populations that live together in a
defined area.
Levels of Organization
4.) Ecosystem- collection of all the
organisms that live in a particular
place with the nonliving
environment.
5.) Biome- group of ecosystems that
have the same climate and similar
communities.
6.) Biosphere- our beautiful Earth.
Ecological Methods
Ecologists use a wide range of tools
and techniques to study the living
world:
Binoculars
Field guides
Studies of DNA
Radio tags
Ecological Methods
Research is conducted using three
basic approaches:
1) Observing- The first step in
asking ecological questions.
2) Experimenting- Used to test
hypotheses.
3) Modeling- Gain insight into
complex phenomena.
Section 2 Notes
Energy Flow
Producers
Organisms use energy from the
environment for life processes
Sunlight is the main source of
energy for life on Earth
Organisms that use energy in
sunlight or chemicals to make food
are called autotrophs
Also known as producers
Producers
Two ways to make food
1. Use light to make food
Photosynthesis
Process in which carbon dioxide and
water react to produce carbohydrates
and oxygen
Plants, some algae, and some
bacteria carry out photosynthesis
Producers
2. Use energy stored in organic
chemical compounds
Chemosynthesis
 Process in which autotrophs use chemical energy
to make carbohydrates
 Only certain bacteria can carry out
chemosynthesis
Consumers
Organisms that rely on other
organisms for food are called
heterotrophs
Also known as consumers
Five types of heterotrophs
1. Herbivores – get energy from eating
only plants
 Ex. Cows, Deer
Consumers
Types of heterotrophs cont.
2. Carnivores – get energy from eating
only animals
 Ex. Snakes, dogs
3. Omnivores – get energy from eating
both plants and animals
 Ex. Humans, Bears
Consumers
Types of heterotrophs cont.
4. Detritivores – feed on the remains
or wastes of other animals
 Ex. Earthworms, mites
5. Decomposers – break down organic
matter
 Ex. Fungi (mushrooms), bacteria
Feeding Relationships
Energy flows through an ecosystem
in one direction
Sun  Autotrophs  Heterotrophs
Food chains show the one-way flow
of energy in an ecosystem
Might consist of grass (producer) a cow
(herbivore) and a human (omnivore)
Feeding Relationships
A food web links together all of the
food chains in an ecosystem
Ex. Rabbits may also feed on that
grass. These rabbits could be eaten by
coyotes, or humans
Feeding Relationships
Each step in a food chain is called a
trophic level
Producers are at the first level
Consumers make up the higher
levels
Each consumer depends on the
trophic level below it for energy
Ecological Pyramids
 Ecological pyramids are diagrams that
show the relative amounts of energy or
matter at each trophic level
 Only about 10% of energy available at
one trophic level is passed on to
organisms at the next level
 1/10th of solar energy captured by the
grass
 1/10th of that energy captured by cow
 1/10th of that energy captured by human
Ecological Pyramids
Three types of pyramids
1. Energy pyramids – show how much
energy is available at each trophic level
2. Biomass pyramids – show the
biomass at each trophic level
 Biomass is the amount of living tissue
3. Pyramid of numbers – shows the
relative number of individual organisms
at each trophic level
Section 3
Cycles of Matter
Recycling in the Biosphere
Matter is recycled within and
between ecosystems through
biogeochemical cycles.
It moves through the air, plants,
trees, water, animals, and other
organisms as it is used,
transformed, moved and reused.
The Water Cycle
Evaporation occurs when water
changes from a liquid form to an
atmospheric gas.
Transpiration occurs when water is
evaporated from the leaves of
plants.
The Water Cycle
How it happens:
The sun heats the atmosphere.
The warm moist air rises and cools.
The vapor condenses into tiny droplets
that form clouds.
When the droplets are large enough it
is returned to Earth in the form of
precipitation.
Nutrient Cycles
You obtain chemical substances
from the foods you eat called
nutrients.
These are needed to build tissues
and carry out life functions.
There are three types of nutrient
cycles:
1st Nutrient Cycle
 1.)
The Carbon Cycle-
Carbon is an important component of
animal skeletons.
It is found in several kinds of rocks.
Carbon dioxide gas is in the
atmosphere and is used during
photosynthesis.
It is given off by plants and animals
during respiration.
1st Nutrient Cycle
4 types of processes move carbon
through its cycle:
Biological processes (photosynthesis,
respiration, and decomposition)
Geochemical processes (erosion and
volcanic activity)
Biogeochemical processes (burial and
decomposition of dead organisms)
Human activities (mining, cutting and
burning forests, burning fossil fuels)
2nd Nutrient Cycle
2.) The Nitrogen CycleNitrogen is required to make amino
acids.
Nitrogen gas makes up 78% of the
atmosphere.
Ammonia nitrate and nitrite ions are
found in wastes products and in
dead/decaying matter.
2nd Nutrient Cycle
It exists in several forms in large
bodies of water.
Human activity adds nitrogen in the
form of nitrate (plant fertilizer).
Third Nutrient Cycle
3.) The Phosphorus CycleIt forms part of DNA and RNA
molecules.
It remains mostly on land in rock and
soil minerals, and in ocean sediments.
When the minerals and sediments wear
down it is washed into rivers and
streams where it dissolves.
It later makes it way to the ocean again
and is used by marine organisms.
Nutrient Limitation
If a nutrient is in short supply it will
limit an organisms growth.
This is known as a limiting nutrient.
In some cases fertilizers are applied
to crops to boost productivity.
Nutrient Limitation
Nitrogen is the limited nutrient in
bodies of water compared to the
soil.
When there is a large input of a
limiting nutrient there is an increase
in algae production.
If there are not enough consumers
to eat the algae it can disrupt the
ecosystem.