1. Chapter 4
Ecosystems
and
Communities

2. I. The Role of Climate
Day to day conditions of Earth’s atmosphere in a particular place and time
A. Weather =
Average year after year conditions of temp. and precipitation in a particular region
B. Climate =

3. II. Factors that Affect Climate
A. Greenhouse Effect:
1. CO2, methane, & water vapor = Greenhouse Gases
2. These gases act like glass in a greenhouse allowing light to enter but trapping the heat.
3. More greenhouse gases in atmosphere = higher temps.

4. B. Latitude/Solar Energy:
1. Differences in latitude and the angle of heating creates three main climate zones for Earth:
Polar, Temperate, and Tropical.
Page 97
90°N North Pole
Sunlight
Polar
66.5°N
Arctic Circle
Temperate
Sunlight
Tropic of Cancer
23.5°N
Equator
Most direct sunlight 0°
Tropical
Tropic of Capricorn
23.5°S
Sunlight
Temperate
Antarctic Circle
66.5°S
Sunlight
Polar
90°S South Pole

5. C. Heat is transported around the Earth by winds and ocean currents
Earth has three main climate zones. These climate zones are caused by the unequal heating of Earth's surface. Near the equator, energy from the sun strikes Earth almost directly. Near the poles, the sun's rays strike Earth's surface at a lower angle. The same amount of solar energy is spread out over a larger area, heating the surface less than at the equator.

6. III. Tolerance:
A. Any condition beyond optimum range  organism uses more energy for homeostasis and not towards growth and reproduction
B. Every organism has an upper limit & lower limit of tolerance.
C. Anything beyond the limits = cannot survive
D. Tolerance determines a species habitat  place organism lives
the ability to survive and reproduce under a range of environmental circumstances

8. IV. Niche:
A. The role a species plays in its community
(includes what they eat, where it feeds, interactions)
B. No two species can share the same niche in the same habitat
C. Different species can occupy niches that are very similar

9. V. Community Interactions
Occurs when organisms attempt to use the same resources at the same time
A. Competition:
1. Competitive Exclusion Principle:
no two species can occupy the same niche in the same habitat at the same time
Page 101

10. B. Predation:
One organism captures and feeds on another
- Prey = organism being captured
C. Herbivory = herbivore feeds on a producer (plant)
-herbivores can affect the size and distribution of plant populations
D. Keystone Species =
- a species on which other species in an
ecosystem largely depend, such that if it were
removed the ecosystem would change drastically
Example: Sea otters

12. E. Symbiosis: two species living closely together (Page 103)
1. Mutualism:
Both species benefit from relationship
Ex. Flowers and bees
2. Parasitism:
One organism lives in/on another & harms it
Ex. Fleas, ticks

13. 3. Commensalism:
One member benefits & the other is neither harmed/helped
Ex. Barnacles and Whales

14. VI. Ecological Succession
A. Succession  predictable changes in an ecosystem
1. Primary Succession
a. Occurs where no soil exists
b. occurs on rock surfaces formed after volcanoes erupt or a glacier retreats
c. The first species to populate the area are called pioneer species
d. Slows down and the community becomes stable = Climax Community

15. Primary Succession
Page 106

16. 2. Secondary Succession (Page 107)
a. Disturbance changes community without removing soil
b. Forest fire, hurricane, tornado, human activity
c. Takes less time to become a climax community = happens faster

17. VII. Biomes
A. Group of ecosystems with same climate and dominant communities
B. Plants and animals exhibit variations in tolerance =
ability to survive and reproduce under conditions that differ from their optimal conditions
Climate within a small area that differs significantly from the climate around it
Example: A city
C. Microclimate:

18. The Major Biomes Page 111 60°N 30°N 0° Equator 30°S 60°S
Tropical rain forest
Temperate grassland
Temperate forest
This map shows the locations of the world’s major biomes. Other parts of Earth’s surface are classified as mountains or ice caps. Each biome has a characteristic climate and community of organisms.
Northwestern coniferous forest
Tropical dry forest
Desert
Temperate woodland and shrubland
Boreal forest (Taiga)
Tropical savanna
Tundra
Mountains and ice caps

19. VIII. Major Terrestrial Biomes
A. Tropical Rain Forest: 20oC -30oC , greater than 200cm of yearly rain
B. Tropical Dry Forest:
C. Savanna:
D. Desert: -30oC-38oC cool desert or 20oC-49oC in hot deserts, less than 25cm of yearly rain
E. Temperate Grassland: -10oC-25oC, 25-75cm of yearly rain

20. F. Temperate Woodland
G. Temperate (Decioduous) Forest; -10oC-25oC, cm of yearly rain
H. Northwest Coniferous Forest
I. Taiga (Boreal Forest): -30oC-20oC, 30-50cm of yearly rain
J. Tundra: -40oC-10oC, less than 25cm of yearly rain

21. IX. Aquatic Ecosystems
Determined by depth, flow, temp., & available nutrients
1. Water Depth:
a. well-lit upper layer = photic zone
- Algae and other producers can grow only in this
thin surface layer
b. Aphotic zone - permanently dark - below photic
zone
- Chemosynthetic autotrophs only producers that
survive here
c. Benthos = organisms that live on the bottom of
lakes, streams and oceans  called the benthic zone

22. B. Freshwater
1. Rivers & Streams:
-originate in mountains or hills
2. Lakes & Ponds:
-provide habitats for organisms such as
plankton  free-floating organisms
Unicellular algae
Phytoplankton =
Unicellular animal-like that feed on phytoplankton
Zooplankton =

23. 3. Freshwater Wetland
- Water covers soil or is present at or near the surface of the soil at least part of the year
- Nutrient-rich & serve as a breeding ground
- Three Types:
Bogs
Marshes
Swamps

24. C. Estuaries
1. Where rivers meet the sea
2. Mixture of fresh and salt water
3. Large fluctuation of salinity
4. Spawning/nursery grounds
5. Types:
Mangrove swamps
Salt marshes

25. X. Marine Ecosystems
A. Ocean is divided into zones based on the depth and distance from shore:
1. Intertidal Zone
- alternating exposure to direct sunlight and submergence, salinity changes, rocky substrate
2. Coastal Ocean – low-tide mark to outer edge of
continental shelf
3. Open Ocean
- two main zones: Photic and Aphotic
4. Benthic Zone – ocean floor

26. Continental slope and continental rise
Marine Ecosystems
Photic zone
Land
200 m
1,000 m
Intertidal zone
Coastal
ocean
Open
ocean
4,000 m
Aphotic zone
Benthic zone
6,000 m
The ocean can be divided into zones based on light penetration and into zones based on depth and the distance from shore. Each zone contains a characteristic assemblage of organisms.
Ocean
trench
10,000 m
Continental slope and continental rise
Abyssal
plain
Continental
shelf
Page 120

27. 4-1 The Earth’s polar zones are cold because
A. they are never heated by the sun.
B. at the poles, the sun's rays are at a very low angle.
C. the greenhouse effect does not occur at the poles.
D. heat is transported from the poles to the equator.

28. 4-1
The upward movement of warm air and the downward movement of cool air creates
A. upwellings.
B. air currents.
C. ocean currents.
D. the greenhouse effect.

29. 4-1 Earth's temperature range is maintained by
A. the greenhouse effect.
B. climate zones.
C. ocean currents and winds.
D. latitude differences.

30. 4-1 Variation of temperature in the temperate zone is due primarily to
A. air and ocean currents.
B. the greenhouse effect.
C. variation in the sun’s energy production.
D. latitude and season.

31. 4-1 The tropical zone is warm all year long because
A. the sun’s angle changes the most in that part of Earth.
B. ocean water is warmest near the equator.
C. it receives direct or nearly direct sunlight year-round.
D. landmasses in the tropic latitudes hold on to heat.

32. 4-2 Which of the following is a biotic factor in a bullfrog's niche?
A. water
B. a heron
C. climate
D. day length

33. 4-2 An organism’s niche is different from its habitat because
A. The niche does not include the place where the organism lives.
B. the niche includes all the conditions under which the organism lives.
C. the niche includes only abiotic factors.
D. the niche includes only biotic factors.

34. 4-2
The attempt by organisms of the same or different species to use a resource at the same time in the same place is called
A. competition.
B. predation.
C. symbiosis.
D. cooperation.

35. 4-2
An association between two species in which one species benefits and the other is neither helped nor harmed is called
A. symbiosis.
B. mutualism.
C. commensalism.
D. parasitism.

36. 4-2
When a volcano erupts and completely destroys an ecosystem, the first species to populate the area are usually
A. grasses and shrubs.
B. pioneers such as lichens.
C. small plants such as mosses.
D. small animals such as rodents.

37. 4-3
When the climate in a small region of a biome is different from the overall climate of the biome, the region’s climate is called
A. tolerance.
B. a harsher climate.
C. a microclimate.
D. a local variation.

38. 4-3
The ability of an organism to survive under conditions that differ from its optimal condition is called
A. niche.
B. tolerance.
C. variation.
D. succession.

39. 4-3
Which of the following biomes is characterized by less than 25 centimeters of annual precipitation?
A. tropical savanna
B. desert
C. boreal forest
D. temperate grassland

40. 4-3
Which of the following biomes is characterized by a mixture of deciduous and coniferous trees?
A. temperate woodland and shrubland
B. boreal forest
C. temperate forest
D. tropical dry forest

41. 4-3
Which of the following biomes is characterized by the presence of permafrost?
A. boreal forest
B. temperate grassland
C. northwestern coniferous forest
D. tundra

42. 4-4
Which of the following factors is important in determining the type of aquatic ecosystem found in a specific area?
A. geographic location
B. amount of dissolved chemicals
C.the percentage of land covered by water
D. the kinds of organisms in the water

43. 4-4
The two types of freshwater ecosystems are distinguished by whether or not they have
A. high oxygen content or low oxygen content.
B. phytoplankton or zooplankton.
C. high temperature or low temperature.
D. flowing water or standing water.

44. 4-4
Coastal wetlands that are widespread in tropical regions such as southern Florida and Hawaii are known as
A. detritus.
B. bogs.
C. mangrove swamps.
D. benthos.

45. 4-4 Coral animals cannot grow in water that A. contains salt.
B. contains oxygen.
C. is cold.
D. receives sunlight.

46. 4-4 The zone that covers the ocean floor is the A. benthic zone.
B. abyssal plain.
C. continental shelf.
D. continental rise.