Ecology Study Guide: You WILL NEED TO READ the information below in order to answer SOME of
the QUESTIONS BELOW 
ECOLOGY READING for the ECOLOGY STUDY GUIDE QUESTIONS
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Ecologists trace the flow of energy through ecological communities to discover nutritional
relationships
.
The ultimate source of the energy is the sun, which supplies the energy that fuels life
.
Plants use the sun’s energy to manufacture food in a process called photosynthesis
.
Organisms that use energy from the sun or energy stored in chemical compounds to manufacture their
own nutrients are called autotrophs
.
Although plants are the most familiar terrestrial autotrophs, some unicellular organisms also make
their own nutrients
.
Most other organisms depend on autotrophs for nutrients and energy. These are the producers in a
food web
.
The consumer is a heterotrophy which means they are not capable of making their own food so they
obtain food for energy by eating other organisms
.
When you pick a pear from a tree and eat it, you are consuming carbon, nitrogen, and other elements
the tree has used to produce the fruit. That pear also contains energy from the sunlight trapped by the
tree’s leaves while the pear was growing and ripening
Ecologists use food chains and food webs to model the distribution of matter and energy within an
ecosystem
.
Each organism in a food chain represents a feeding level in the passage of energy and materials
.
A food chain, the simplest path that energy takes through the ecosystem, represents only one possible
route for the transfer of matter and energy in an ecosystem
1st trophic level consists of PRODUCERS (green plants, other autotrophs). PRIMARY producers
capture the sun’s energy during photosynthesis
2nd trophic level consists of primary CONSUMERS (heterotrophs). Primary consumers that eat green
plans – called herbivores
3rd trophic level, or any higher trophic level, consists of CONSUMERS. Consumers that eat primary
consumers are called carnivores; consumers that eat both producers, AND primary consumers are
called omnivores
.
A food web is a more realistic model than a food chain because most organisms depend on more than
one other species for food. These food webs also show how energy is lost from one level to the next
.
This energy is lost to the environment as heat generated by the body processes of
organisms
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Sunlight is the primary source of all this energy, so energy is always being replenished
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Matter, in the form of nutrients, also moves though the organisms at each level. But matter cannot be
replenished like the energy from sunlight
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The atoms of carbon, nitrogen, oxygen and other elements make up the bodies of organisms alive
today are the same atoms that have been on Earth since life began. Matter is constantly recycled
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All life on Earth is based on carbon molecules
.
Atoms of carbon form the framework for proteins, carbohydrates, fats and other
important molecules
.
More than any other element, carbon is the molecule of life. The carbon cycle starts with the
autotrophs
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During photosynthesis, energy from the sun is used to convert carbon dioxide gas into energy rich
carbon molecules
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Autotrophs use these molecules for growth and energy
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Heterotrophs, which feed either directly or indirectly on the autotrophs, also use the carbon molecules
for growth and energy
.
When the autotrophs and heterotrophs use the carbon molecules for energy, carbon dioxide is released
and returned to the atmosphere
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If you add nitrogen fertilizer to a lawn, houseplants, or garden, you may see that it makes the plants
greener, bushier, and taller
.
Even thought the air is 78% nitrogen, plants seem to do better when they receive nitrogen fertilizer. .
This is because plants cannot use the nitrogen in the air. They use nitrogen in the soil that has been
converted into more usable forms
.
Lightening and certain bacteria convert the nitrogen in the air into these more usable forms
Chemical fertilizers also give plants nitrogen in a form they can use. Plants use the nitrogen to make
important molecules such as proteins
.
Herbivores eat plants and convert nitrogen containing plant proteins into nitrogen-containing animal
proteins
After you eat your food, you convert the proteins in your food into proteins used in humans
Urine, an animal waste, contains excess nitrogen
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When an animal urinates, nitrogen returns to the water or soil
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Bacteria in the ground transform much of this nitrogen so that it can be stored in and used by plants,
while returning some of it to the air. When organisms die, their nitrogen molecules are recycled.
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Food provides molecules that serve as fuel and building material for all organisms
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Organisms get energy by oxidizing their food, releasing some of its energy as thermal energy
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1) Please list the 3 symbiotic relationships, define each, and give 1 example for each.
2) Please list and describe the 3 trophic levels within a food chain
Please choose from the following words to complete the definitions/statements
a) Ecosystems b) population c) density-dependent factors d) density-independent
factors e) biotic factors f) abiotic factors g) sunlight h) photosynthesis i)oxidizing
j) molecules k) food chain l) trophic level m) autotroph n) heterotroph
o)decomposer
p) food web
q) energy pyramid
r) number pyramid
s) biomass pyramid t) metabolism
3) ________________ Limiting factors that affect large populations more than small ones and
include competition, predation, parasitism, and disease.
4) ________________ Factors that are living
5) ________________Complex, interactive systems that include both biotic and abiotic
components of the environment.
6) Almost all food energy comes originally from __________________. Energy entering
ecosystems as ________________ (same word as 1st word) is transferred by producers into
chemical energy through the process of ______________________.
7) ___________________ a group of organisms belonging to the same species that live in a
particular
8) Food provides ____________________ that serve as fuel and building material for all
organisms.
9) ______________Limiting factors that occur regardless of the size of the population and reduce
the size of all populations within the area. These can include weather related activities,
pollution, and natural disasters.
10) __________________ Non-living factors
11) This pyramid represents the energy available for each trophic level in an
ecosystem.______________ _______________
12) A __________ _____________ is the simplest path that energy takes through an ecosystem.
13) ____________________ is the set of chemical reactions involved in storing fuel (food)
molecules and converting fuel (food) molecules into energy.
14) Animals get food from _________________their food, releasing some of its energy as heat.
15) Each level in the transfer of energy through an ecosystem is called a ___________ __________
16) This pyramid represents the total mass of living organic matter at each trophic level in an
ecosystem.
17) Producers are also known as _______________________, while primary consumers are also
known as _________________.
18) A ____________ ______________ represents many interconnected food chains.
19) A _______________________ is a heterotroph that breaks down organic material and returns
the nutrients to soil, water, and air making the nutrients available to other organisms.
20) This pyramid represents the # of individual organisms available for energy at each trophic
level in an ecosystem. __________________ ______________________
21) This pyramid represents the total mass of living organic matter at each trophic level in an
ecosystem. __________________ ______________________