ECOLOGY
Upward Bound
Ecology
The study of interactions that take place between organisms and their environment
Ecological Research
Involves using descriptive and quantitative methods
Biotic Factors
All the living organisms that inhabit an environment
Abiotic Factors
Nonliving parts of an organism’s environment including air currents, temperature,
moisture, light, nutrients, and soil
Obtaining energy
The ultimate source of all energy within ecosystems comes from the sun
Autotrophs
Autotrophs (producers) are organisms that use light energy to make energy-rich compounds (food)
Examples of autotrophs include plants and algae
Heterotrophs: The consumers

A heterotroph is an organism that cannot make its
own food and must feed on other organisms
 Herbivore
– feeds only on plants
 Carnivores – feed on other heterotrophs
 Scavengers – feed on dead heterotrophs
 Omnivores – feed on plants and animals
 Decomposers – break down complex compounds of
dead and decaying plants and animals into simpler
molecules to be absorbed
Carnivore
Scavenger
Flow of matter and energy in ecosystems
Food chains – a simple model that
scientists use to show how matter
and energy move through an
ecosystem
Arrows indicate the direction in
which energy is transferred from
one organism to the next
Trophic Levels in food chains

Each organism in a food chain represents a feeding
step or trophic level describing the passage of
energy and materials
Ecological Pyramids

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A model used to show how energy flows through an
ecosystem
The first level represents autotrophs
The next level represents primary consumers
The next level represents secondary consumers and
so on. . .
Ecological pyramids

Pyramids of energy illustrate the energy decrease
at each successive trophic level
 Only
ten percent is available for use in metabolism,
building tissue, and giving off heat

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Population sizes decrease at each successive trophic
level (usually)
Biomass – total weight of matter at each trophic
level decreases
Food Web
Food webs are models that represent all the possible feeding relationships at
each trophic level in a community
FIG. 1-4
The biosphere
Cells
10 µm
Organs and
organ systems
Cell
Ecosystems
Organelles
Communities
1 µm
Atoms
Tissues
50 µm
Molecules
Populations
Organisms
Levels of Organization
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Biosphere
Ecosystem – The community of organisms and how
they relate to each other and the abiotic
environment
Community – The set of interacting populations in a
defined place and time
Population - a group of organisms, all the same
species which interbreed and live in the same area
at the same time
Organism
Habitat

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The place where an organism lives out its life
Niche – all strategies and adaptations a species
uses in its environment, how it meets needs for food,
shelter, survival, and reproduction