CP Biology
2015-2016
Name
UNIT 2A: Introduction to Ecology
Science is a body of knowledge and skills acquired through
The existence of life on Earth depends on interactions among organisms
systematic experimentation and observation to describe natural
and between organisms and their environment. There is a great diversity
phenomena; or, more simply, it is a “way of knowing”. The process
among living organisms yet there are similar characteristics that all
of science helps biologists investigate how nature works at all
organisms share.
levels, from the molecules in cells to the biosphere.
Where is the biosphere located AND what does it include?__ It
extends from 8km above the Earth’s surface to as far as 11km
below the surface of the oceans.____________
3.1 What is Ecology?
Biosphere: all life on earth and all parts of earth in which
life exists including land, water and air or atmosphere.
Ecology: the scientific study of interactions among
organisms and between organisms and their physical
environment.
How is economics linked with ecology? Humans live within the
biosphere and depend on ecological processes to provide such
essentials as food and drinkable water that can be bought and
sold or traded.______________
Levels of Organization in the biosphere: (use #s to label from USG)
Interactions within the biosphere produce a web of
interdependence between organisms and the environments
in which they live.
Organisms respond to their
environments and can also change their environments;
therefore, biosphere is dynamic and ever-changing.
How is economics linked with ecology?
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*Practice Task:In the space below, fill in the blanks with the
appropriate levels of organization using the word bank below.
Word Bank
Biome
Community
Population
Biosphere
Ecosystem
Organism
biosphere
biome
ecosystem
community
population
organism
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Environment: all conditions or factors surrounding an
organism
**Environmental conditions include both biotic and abiotic
factors**
Biotic Factors
_____ Biological (living) influences on an organism____________
________________________________________________
Pick any organism and name 4 biotic factors relating to it:
Organism: __deer____________
1. ___grass___________________________
2. ___wolves__________________________
3. ___trees__________________________
4. ___squirrel________________________
Abiotic Factors
_____ Physical components of an ecosystem______________
________________________________________________
Using the same organism you picked earlier, name 4 abiotic factors
relating to it
1. ___water___________________________
2. ____climate / weather______________
3. ____rocks__________________________
4. ____oxygen_________________________
Abiotic and Biotic factors are closely linked. Many physical
(abiotic) factors can be strongly influenced by the activities
of organisms. The dynamic mix of biotic and abiotic factors
shapes every environment.
Is a mucky shoreline around a pond strictly part of the physical
(abiotic) environment? Explain.
_____No, there are living organisms within the muck/mud (i.e.,
bacteria, algae, snails, etc.)_______________________
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3.2 Energy, Producers, and Consumers
What would happen to the amount of oxygen in our
atmosphere without the presence of photosynthetic
Energy is needed to power life's processes (including growth,
producers?
reproduction, metabolism, etc.). No organism can "create"
___ the amount of oxygen would decrease (it is a byproduct
energy. Organisms can only use energy from other sources.
You may have wondered where this energy comes from and how of photosynthesis) to such a low level that heterotrophs could
not undergo cellular respiration!._______________
it is transferred from one organism to another.
For most life on Earth, sunlight is the ultimate energy source.
However, for some organisms, chemical energy stored in
inorganic chemical compounds serves as the ultimate energy
source for life processes.
Name three examples of organisms which are
autotrophs (primary producers):
1. __plants_____________________
2. __some protists – like algae
The following are the only organisms that can capture energy
from sunlight or chemicals and convert it into forms that living
cells can use, therefore they are essential to the flow of energy
through the biosphere. They store energy in forms that make it
available to other organisms that eat them.
3. __cyanobacteria (formerly, blue-green algae)
Autotrophs: organism that is capable of capturing energy from
sunlight or chemicals and use to produce its own food from
inorganic compounds;
Photosynthesis
Also Known As: Producers
The next process is how the best-known and most common
primary producers harness solar energy
Photosynthesis: captures light energy and uses it to power
chemical reactions that convert carbon dioxide and water into
oxygen and energy-rich carbohydrates such as sugars and
starches
Chemosynthesis: Chemosynthetic autotrophs do not need
sunlight. Often they may be found in extreme environments
such as tidal marshes along the coast, or around hot springs or
volcanic vents on the ocean floor. Here they utilize the energy
stored in chemical bonds of inorganic molecules such as
hydrogen sulfide to make energy-rich carbohydrates.
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Consumers are organisms that cannot directly harness energy
from the environment as autotrophs do.
Heterotrophs: organism that obtains its energy by consuming
other organisms
Name three examples of organisms which are heterotrophs
(consumers).
1. __all animals________________
2. __all fungi__________________
Also Known As: Consumers
3. ___some bacteria, some protists
Consumers are classified by the specific ways in which they acquire energy and nutrients from other organisms.
The type of "food" eaten may vary widely from one type of consumer to another.
Realize, however, that organisms in nature often do not stay inside the tidy categories in which ecologists place them.
For example, some animals often described as carnivores will scavenge if they get a chance.
Examples of:
Herbivores: organisms that obtain energy by eating plant
Herbivores: _deer, cows, squirrels_________________
leaves, roots, seeds, and or fruits
___________________________________________________
Carnivores: organisms that obtain energy by eating animals
Carnivores: __lions, snakes, dogs____________
___________________________________________________
Omnivores: organisms that obtain energy by eating both plants
Omnivores: _humans, bears, pigs____________________
and animals
___________________________________________________
Decomposers: organisms that break down and obtain energy
Decomposers: _bacteria and fungi___________________
from dead organic matter
___________________________________________________
Detritivores: organisms that feed on detritus which are the
Detritivores: __earthworms, snails, shrimp, mites, crabs
small pieces of dead and decaying plant and animal remains
___________________________________________________
Scavengers: animals that consume the carcasses of other
Scavengers: _vulture, hyena________________________
animals
___________________________________________________
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3.3 Food Chains and Food Webs
Example of a Food Chain
Energy flows through an ecosystem in a one-way stream,
from primary producers to various consumers.
You can think of energy as passing through an ecosystem
along a food chain. Some food chains are simple, being
composed of only two steps, while others can be longer
with as many as 5 or 6 steps!
Food chain: a series of steps in an ecosystem in which
organisms transfer energy by eating and being eaten
Construct a 4-step food chain below:
grass
 __grasshopper___  ___snake______  ___hawk_____
A common type of primary producer found at the base of
many aquatic food chains is a mixture of floating algae
called phytoplankton and attached algae.
Partially because many animals eat more than one kind of
food, a single, simple food chain is usually insufficient to
describe the complicated feeding relationships typically
found in an ecosystem.
Food Web: network of complex interactions formed by the
feeding relationships among the various organisms in an
ecosystem; a food web can also be defined as a series of
interconnected food chains in an ecosystem.
Therefore studying a food web may be more appropriate
when trying to understand the flow of energy and materials
in a complex ecosystem
What do you think would happen to the ecosystem above if the
algae were killed off?___Since algae are the primary producers in
this ecosystem, providing the energy necessary for life processes
in this ecosystem, life in this ecosystem would not continue if
algae were killed off _______________________________________
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All of the animals in the food web shown to the right,
ultimately depend on krill. If the marine algae
population is disturbed, then there may be changes in
all of the populations connected in this food web.
Killer whales indirectly depend on krill for survival.
The food web shows that killer whales depend directly
on blue whales and leopard seals to obtain energy.
Blue whales consume krill for energy; therefore, since
killer whales consume blue whales, killer whales
indirectly depend on the krill population for energy.
Leopard seals consume Adelie penguins which in turn
consume krill, so again, killer whales depend on krill
for energy, indirectly. In addition, krill are the only
herbivores in this web, so they are the only organisms
that consume the primary producers of this web.
Primary producers are always at the first trophic level
of a food chain or food web.
Trophic level: each step in a food chain or a food web
Food chains and food webs cannot go on forever; in other words they
cannot have an unlimited number of trophic levels. Why do you think
this is true? _ Only a small portion of the energy available at each level of the
food web or chain is transferred to the next level (on average, 10 %).
Eventually, as we move up the energy pyramid, the amount of energy transferred
will not be enough to support the life processes of another trophic level.
Some might make an analogy of decomposers being like earth's
"recycling center". Summarize the importance of decomposers and
detritivores in food webs.
Decomposers break down any dead organisms that have not been consumed into
detritus. Detritivores breakdown both decomposers and the detritus that they
produce to obtain energy. Without decomposers, nutrients would be locked
forever in dead organisms. Instead, these nutrients re-enter the food web
through primary producers; they are recycled.
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