Unit 2: Ecology
Test Date: ___________________________
Fundamental Concept and Skill
1. Organization of Life (from lowest to highest)
a) Organism: individual species (groups of organisms can interbreed and have viable
offspring).
b) Population: groups of individual species.
c) Community: made up of several populations of species.
d) Ecosystem: is made up of the interactions among the populations and their abiotic
influences in the community.
e) Biome: large group of ecosystems that are grouped according to their climates.
f) Biosphere: larger portions of the earth that can support life (e.g. atmosphere, soil, water).
2. Illustrate energy flow in a community by correctly drawing a food chain and a food web
including producer, primary, secondary and tertiary consumers.
a) Energy enters and leaves an ecosystem.
b) Energy from the sun enters an ecosystem through producers (autotroph) at the 1st trophic
level.
c) Energy flows from the primary producers (1st trophic level), to the
first order consumers (heterotroph, herbivore, 2nd trophic level), to the
second order consumers (omnivore, carnivore, 3rd trophic level), and to the
tertiary consumers (mainly carnivore, 4th trophic level).
d) As energy flows from one level to another a large part of it is lost through heat and work
done by organisms. As you go from one level to the next in the food chain energy
deceases by 10% each step, thus creating an energy pyramid.
e) A food chain diagram must start with a producer, and the arrows must point in the
direction of energy flow. For example, the arrows will point from producers to the primary
consumer.
f) The flow of energy is recycled by decomposers and scavengers. Their niche is to assist
in breaking down dead or decaying material as their food source.
3. Describe ways that organisms in an ecosystem cooperate and compete.
a) Symbiosis: close and permanent relationship between organisms of different species.
b) Parasitism: relationship when one organism benefits and the other is harmed (ex: fleas on a
dog).
c) Commensalism: relationship when one organism is benefited and the other is neither
harmed nor benefited. (ex: remora on a shark).
d) Mutualism: relationship when both organisms benefit (ex: elephant and bird)
e) Competition: organisms compete for resources such as food, space, sunlight, mates, water,
etc.
4. Population Biology
Types of growth:
 Linear growth: straight line
 Exponential growth: “j” shaped curve
a) Carrying Capacity: the number of organisms an environment can support over time.
Is represented by the letter “k”
b) Density dependent factors: disease, competition and parasites increase as density of
population increases (ex: 3rd world country diseases).
c) Density independent factors: abiotic factors such as weather
d) Predation: the relationship between predator and prey.
e) Demographic trends: effects of birth and death rate
Reading
p. 64
pp. 6773
p.93
pp.119123
5. Describe how nutrients (matter) cycle in ecosystems; Nitrogen, Carbon and Water
a) Carbon dioxide is fixed into carbohydrates by producers.
b) The carbon from the producers passes to the consumers
c) Through cellular respiration, both producers and consumers make carbon dioxide.
d) When consumers breathe, they release carbon dioxide into the atmosphere.
e) When consumers decompose by either decomposers/burning, carbon dioxide is released
into the atmosphere.
f) Carbon exists in the soil as fossil fuels. The only way to return to the soil is
decomposition.
g) Nitrogen from soil is absorbed (fixed) by the roots of producers and when producers are
eaten the nitrogen is passed into the herbivore where they help make proteins. When the
organism dies the nitrogen is released into the atmosphere/soil.
h) Water Cycle : evaporation (from large bodies of water) and transpiration (from plants) and
respiration (from animals) forms precipitation which is reabsorbed into the ground or runs
of into large bodies of water.
6. Describe the patter of succession in an ecosystem.
a) Primary succession: new land (volcano, glacier) begins to be inhabited by a pioneer species
(producers) which eventually develops into a complex community.
b) A piece of land in Northern Virginia is cleared so that nothing remains but the soil
(secondary succession).
c) Seeds borne by the wind fall onto the soil. The fast growing, shallow rooted, sun-loving
plants will grow first (and fastest).
d) Insects borne by the wind live on the plants.
e) These plants and insects live and die, decompose and build up the soil, changing the
environment and making the environment more hospitable for different species of plants
and organisms (weathering turns exposed rock to soil).
f) Climax Community: a stable mature community that undergoes little change and which
maintains itself if left undisturbed.
7. Biomes
Be able to compare and contrast the 8 different biomes.
a) How do biomes relate to longitude and latitude?
b) Ice, Tundra, Taiga (coniferous forest), temperate (deciduous) forest, tropical rain forest,
grassland (and savanna), desert, water (fresh and marine).
8. Environmental Influences
Limiting factors are biotic and abiotic factors that restrict the life of an organism.
a) Biotic factors: any living organism that affects the life of another organism.
b) Abiotic factors: nonliving influences on an organisms life.
c) Range of Tolerance ability to withstand fluctuations in biotic and abiotic environmental
influences.
Assessments and Activities:
 Vocabulary for unit
 Food Chain and Food Web Design (the Biological Budget)
 Biome Project
 Oh Deer!
 How much Soda?
 Lions and Hyenas movie
 Biodiversity (types of trees)
 Nitrogen Cycle game
pp. 7479
pp. 9497
pp. 98112
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