Principles of Ecology - Chapter Review
13.1 Ecologists Study Relationships
I.
_​Ecologists​_Study Relationships at Different Levels of Organization
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__​Ecology​__- the study of the interactions among living things, and between living things and their
surroundings.
__​Organism​___- one individual living thing.
_​Population​_____- is a group of the same species that live together in one area.
_​Community​___- A group of different species that live together in an area.
_​Ecosystem​____- includes all of the organisms as well as the climate, soil, water, rocks, and other
nonliving things in an area.
_​Biome​_____- is a major regional or global community of organisms. A binome is usually defined by
the climate and the plant communities that live in an area.
II. Ecological Research Methods Include Observation, Experimentation, and Modeling.
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___​Observation​__- the act of carefully watching something over time. Observation may be short or
long term studies.
___​Experimentation​_______- An experiment in a natural setting gives a better picture of how
organisms really interact.
- An experiment in a_______setting______ allows for more control of variables.
_____​Modeling​______- these can be used to explore organisms and whole ecosystems in ways that
would not be possible in a natural setting.
- Models use real _data_____to predict outcomes for different situations.
13.2 Biotic and Abiotic Factors
I.
An ecosystem includes both biotic and abiotic factors
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___​Biotic​____- factors are living things, such as plants, animals, fungi, and bacteria
____​Abiotic​_______ - factors are nonliving things, such as temperature, moisture, wind, rocks, and
sunlight
II. Changing one factor in an ecosystem can affect many other factors
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______​Biodiversity​______- the variety of living things in an ecosystem.
___​Keystone​________Species - a species that has an unusually large effect on its ecosystem.
13.3 Energy in Ecosystems
I.
_______​Producers​_______Provide Energy for other Organisms in an Ecosystem
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Producers - are organisms that make their own __​Food_​__. Plants and other photosynthesizing
organisms are producers. Producers are also called ____​Autotrophs​_________.
_​Consumers​____________- are organisms that get their energy by eating other organisms, including
plants and animals. Consumers are also called__​Heterotrophs​______.
II. Almost All Producers Obtain Energy from __​sunlight​_______
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___​Photosynthesis​__________- the process by which plants and protists (such as algae) make food
through sunlight. These sugars are used for __​cellular respiration​___________.
__​Chemosynthesis​_______- life forms that make their own food through chemicals as an energy
source - not the Sun. (they can also live in Hot Springs)
13.4 Food Chains and Food Webs
I.
_​Food Chain​_____- shows the feeding relationships for a single chain of producers and consumers
Example: grasses ---> rabbits -----> snakes -----> hawks
II. Types of Consumers
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__​Herbivores​_____- eat only plants (such as rabbits)
____​Carnivores​____ - eat only meat (such as hawks)
____​Omnivores​_______ - eat both meat and plants (such as humans)
___​Detritivores​________ - organisms that eat dead plant and animal matter (earthworms are an
example)
___​Decomposers​______- detritivores that break down plant and animal matter into simpler
compounds. Fungi, for example, are decomposers - return nutrients to the ecosystem.
○ __​Specialists​____- Organisms that have a very selective diet - they can be very sensitive to
population changes (example - Florida Snail Kites only eat snails)
● __​Generalists​_____- eat a variety of different organisms (example includes wolves).
III. Trophic Levels
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__​Trophic Level​_______- each link of the food change - each level is called a Trophic Level.
__​Producers​_____- bottom level - plants mostly - gain their energy from the Sun.
__​Primary​ ____Consumers - herbivores mostly that eat producers.
___​Secondary​_______Consumers - Carnivores and Omnivores that primarily eat Primary Producers
___​Teritiary​____Consumers (Apex Predators) - carnivores that eat secondary and primary consumers.
IV. A Food Web Shows a Complex Network of Feeding Relationships
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__​Food web​___- Complex network of feeding relationships and the related flow of energy between
trophic levels.
In general, _​10%​__of the energy acquired in consuming a lower trophic level is passed on to the next
level. 90% of the energy received will be burned off - mostly through heat.
13.5 Cycling Matter
I.
Water Cycles Through the Environment
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___​Hydrologic​_____Cycle - the water cycle, is the circular pathway of water on Earth. From the
Atmosphere, to the surface, and back to the Atmospheres - including all living things.
Two ways that water enters the atmosphere
1. ___​Evaporation​______- water becoming vapor
2. ___​Transpiration​_______- water evaporating from plants
II. Elements Essential for Life also Cycle through Ecosystems
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__​Biogeochemical​___________cycle - The movement of a particular chemical through the living and
nonliving parts of an ecosystem.
● 4 types of Biogeochemical cycles:
1. _​Oxygen​____ Cycle - Most organisms use oxygen for cellular respiration - plants will release
oxygen as a waste product.
2. ____​Carbon​______Cycle - Carbon is a main component of carbohydrates, proteins, fats, and
all of the other molecules that make up living things
- Plants convert carbon dioxide from the air into carbohydrates, which get passed
on as organisms eat each others.
3. __​Nitrogen​___Cycle - Much of the Nitrogen cycle happens underground.
- Nitrogen fixation - some bacteria can turn nitrogen gas into ammonia
- Nitrates are used by plants to make amino acids and proteins.
4. ___​Phosphorous​_____ Cycle - this cycle takes at ground level - Phosphate is released by the
slow breakdown of rocks - plants take phosphates through their roots - Phosphorus then moves through the
food web.
13.6 Pyramid Models
I.
An ___​Energy Pyramid​____Shows the Distribution of Energy Among Trophic Levels
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Energy Pyramid - a diagram that compares the ___​energy​____used by producers, primary consumers,
and other trophic levels.
- shows how much energy is available at each trophic level.
- Energy levels are larger at the bottom and smaller at the top (as energy is lost at each
level).
II. Other Pyramid Models Illustrate an Ecosystem’s Biomass and Distribution of Organisms
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__​Biomass Pyramid​__________
○ ____​Biomass​______- the measure of the total amount, or dry mass, or organisms in a given
area.
○ A diagram that compares the biomass of different trophic levels within an ecosystem
○ Shows the mass of producers needed to support primary consumer - all the way to Tertiary
Consumers.
____​Pyramid of Numbers​__________
○ A pyramid of numbers gives a count of the numbers of individual organisms at each trophic level
in an ecosystem.