Domain IV - Ecology
Ecology
 The study of the interactions between living
things and their environment
 Biotic factors – living organisms in an
ecosystem
 Plants, animals, bacteria
 Abiotic factors – nonliving factors in an
ecosystem
 Climate, light, soil, water
Organization of Life
 Organism – an individual
 A cow
 Population – a group of organisms of the same
species
 A herd of cows
 Community – several different species living in the
same area
 A herd of cows, insects, grass, trees
 Ecosystem – all of the living and nonliving
components of an area
 Cows, insects, grass, trees, rain, streams, rocks
 Biosphere – the entire planet
Populations
 Population density – the number of
organisms living in a given area
 Growth rate – change in population size
 Exponential growth – under ideal conditions, with
unlimited resources, the population increases
exponentially

J-shaped curve
 Logistic growth – as resources become less
available, the growth of a population slows or stops


S-shaped curve
Carrying capacity – the maximum number of individuals
an environment can support
Population Graphs
Limiting Factors
 Density-dependent
limiting factors
 The more organisms
there are, the greater
the impact
 Ex. Competition,
predation, parasitism,
crowding
 Density-independent
limiting factors
 The impact is the
same regardless of
population size
 Ex. Weather, fires,
droughts, floods,
human activities
Energy Flow
 Producers (autotrophs) – organisms that
make their own food
 Plants, photosynthetic bacteria, algae
 Consumers (heterotrophs) – organisms that
need to feed on other organisms
 Trophic levels – each step in a food web or
food chain
 First level is producers, second level is primary
consumers, third level is secondary consumers, etc.
Consumers
 Herbivore – eats plants
 Ex. deer
 Carnivore – eats other animals
 Ex. lion
 Omnivore – eats both plants and animals
 Ex. raccoon
 Decomposer – breaks down dead organisms
 bacteria
Food Chains and Food Webs
 Show the flow of energy and matter through
an ecosystem
Question #1
 In the food chain below, which
population will most likely decrease if
snakes are removed from the food
chain?
a. grass
b. grasshopper
c. frog
d. hawk
Energy Pyramids
 Show how energy
decreases at each trophic
level
 The total energy transfer
from one level to the
next is only about 10%
 Some of the energy is
used by the previous
organism
 Some of the energy is
lost as heat
Other Ecological Pyramids
Water Cycle
Carbon Cycle
Nitrogen Cycle
Phosphorus Cycle
Ecological Succession
 Primary succession –
occurs on surfaces where
no soil exists (no
previous life)
 Glaciers, lava
 Usually lichens and
mosses are the first
organisms (pioneer
species) to move in
 Secondary succession
– occurs when a
disturbance changes the
existing community
without removing the
soil
 Tornado, clear-cutting
 Climax community –
the final, stable
community
Ecological Succession
Resources
 Renewable resource – a natural resource
that is replaced or replenished by natural
processes
 plants, water
 Nonrenewable resource – a natural
resource that is available only in limited
amounts
 Soil, fossil fuels, metals
 Reduce, reuse, recycle
Extinction
 Extinction – the complete disappearance of
a species
 Threatened species – species that are
declining rapidly
 Endangered species – when a species
numbers drop so low that extinction is
almost inevitable
Pollution
 The contamination of soil, water, or air and
is the result of human activity
 Pollutant – any substance that is harmful
or is a waste product
 Air pollution – caused primarily by the
burning of fossil fuels
 Acid rain – rain with a pH lower than 5
 Caused by air pollutants
Pollution
 Water pollution – caused by contaminants
from sewers, industries, farms, and homes
 Enters water sources such as lakes, rivers,
groundwater, and oceans
 Sewage, chemical wastes, fertilizers
Greenhouse effect
 Earth’s atmosphere traps solar radiation
 Keeps Earth at a ‘livable’ temperature
 An increase in the greenhouse effect (due to
excessive greenhouse gases) is believed to be
the cause of global warming
 Ozone layer – prevents lethal doses of UV
radiation from getting to Earth
 The ozone layer is being depleted by CFCs
Question #2
 The theory of global warming suggests
that a trend toward warmer
temperatures on Earth will cause
glaciers to lose mass. A major
consequence of glacial melting is
a. flooding coastal regions
b. destruction of fossil records
c. increased saltiness of the ocean
d. increase in atmospheric carbon dioxide
Plant Adaptations
 Tropism – a plant’s response to their
environment
 Geotropism – response to gravity
 Phototropism – response to light
 Thigmotropism – response to touch
Plant Adaptations
 Hormones – chemical messengers
 Auxin – causes cell elongation
 Gibberellins – growth hormone

Causes plants to grow taller, increases rate of
germination and bud development, larger fruit
 Flowers and cones are adaptations that aid
in plant reproduction
Question #3
 What characteristic of some pine trees
allows the species to survive disasters?
a. modified leaves form needle bundles
b. seeds that germinate after fires
c. pollen that is easily carried by wind
d. bark that is lightly colored
Animal Adaptations
 Behavior – anything an animal does in
response to stimuli in its environment
 Innate behavior – inherited behavior
 Reflexes – automatic responses that require no thinking
 Instincts – may take longer and may be a combination of
behaviors (ex. Mating rituals)
 Territorial – protecting or defending your
territory (which contains breeding grounds,
feeding areas, shelter, etc.)
 Reduces conflict, controls populations, decreases
competition
Animal Adaptations
 Migration – instinctive, seasonal
movement of a species
 Hibernation – the body temperature drops,
oxygen consumption decreases, breathing
rates decrease
 Estivation – animals reduce the rate of their
metabolism due to extreme heat, lack of
food or long periods of drought
Animal Adaptations
 Mechanical defenses – physical structures
such as claws, sharp tusks, stingers, and
shells
 Chemical defenses – chemicals such as
poisons or toxins
 Camouflage – enable the organism to
blend into its environment or appear to be
something they are not
Question #4
 A group of organisms of a certain species
that is in one area at a given time is
known as a(n)
a. ecosystem
b. community
c. population
d. trophic level
Question #5
 As energy flows through an ecosystem,
at each trophic level it
a. increases
b. decreases
c. fluctuates
d. remains the same
Question #6
 Predators often feed on weak or sick
animals in an ecosystem. The role of the
predator is described as its
a. community
b. habitat
c. niche
d. population
Question #7
 The dodder is a land plant that parasitizes
other plants. It grows in long thin strands
that penetrate the host plant and absorb
water, minerals and carbohydrates. Unlike
other land plants, the mature dodder does
not require
nutrients
b. water
c. air
d. sunlight
a.
Question #8
 The state of California has several large
cities and very productive croplands that
divert and use large amounts of water from
rivers. What is one damaging effect of this
use of water from the rivers?
Increased amounts of solid waste pollution in the
oceans
b. Decreased amounts of fresh water in marshes and
estuaries
c. Changes in local rainfall amounts
d. Changes in upstream water tables
a.
Question #9
 Plants that live in the rainforest have many
adaptations to their environment. Some plants
such as vines have adaptations which allow
them to attach themselves to the trunks of
trees. These adaptations allow vines to
successfully compete for which of the following
limiting resources in the rainforest?
sunlight
b. water
c. carbon dioxide
d. oxygen
a.
Question #10
 Lightning causes a fire that destroys all
the plants in a forest community. Which
of the following is most likely to be the
first to occupy the burned area?
a. oak seedlings
b. pine trees
c. grasses and annual plants
d. woody shrubs
Question #11
 Pilot fish and sharks have a relationship
where the pilot fish eats bits of food that
the shark drops or leaves behind. The shark
is unaffected by the pilot fish behavior.
Which of the following best roles describes
the pilot fish?
predator
b. herbivore
c. scavenger
d. parasite
a.
Question #12
 Birds have been observed puffing up
their feathers under certain conditions.
By trapping air between the feathers,
this behavior helps the bird
a. hide from enemies
b. expend less energy during flight
c. shelter offspring
d. trap body heat
Answers
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
D
A
B
C
B
C
D
B
A
C
C
D
Information and Images Obtained
From:
 http://www.doe.k12.ga.us/ci_testing.aspx?P
ageReq=CI_TESTING_EOCT&SubPageReq=
GUIDES
 Google image search
 Campbell, Neil A. and Reece Jane B (2001).
"6". Biology. Benjamin Cummings.
 Miller, Kenneth R. and Levine Joseph S.
(2002). Biology. Prentice Hall.