Welcome
AP Biology
Summer Workshop
July 10th – July 14th
Chapter 50
An Introduction to Ecology and the
Biosphere
The Scope of Ecology
 The scientific study of interactions
between organisms and their environment.
 Ecology incorporates the hypotheticodeductive approach, using observations
and experiments to test hypothetical
explanations.
 Ecologists study the interactions between
the biotic and abiotic environments.
Abiotic Components
 All nonliving chemical and physical factors
in the environment.
– Light
– temperature
– climate
– water
– nutrients
– rocks and soil
Biotic Factors
 All the living factors present in an
environment.
– Animals
– plants
– single-celled organisms
– multi-celled organisms
Aquatic Biomes
 Aquatic biomes occupy the largest area of
the biosphere.
 Major parts of aquatic biomes are:
• photic zone - where sufficient light reaches
• aphotic zone - no light reaches
• benthic zone - bottom of all aquatic biomes
made of sand, organic, and inorganic
sediments.
Aquatic Biomes (con’t)
 Freshwater Biomes include:
• Oligotrophic lakes - deep and nutrient poor due
to unproductive phytoplankton.
• Eutrophic lakes - shallow with a high nutrient
content
• Rivers and Streams - bodies of water
continuously moving
• Wetlands - are covered with water that
supports aquatic plants
• Estuaries - salt and freshwater mix
Aquatic Biomes (con’t)
 Marine Biomes include:
• Intertidal Zone - exposed to daily tidal
fluctuations and wave action
• Coral Reefs - cnidarians secrete a calcium
carbonate shell that seres as the support for
all reef species.
• Oceanic Pelagic Biome - open ocean where
zooplankton feed on phytoplankton which
serves as the food source for nekton (freeswimming)
Terrestrial Biomes
 Distribution of
terrestrial biomes is based
mainly on regional variations in climate.
 Vertical Stratification - canopy, low-tree
stratum, shrub understory, ground layer,
forest floor, and root layer.
 Permafrost - permanently frozen soil
Tropical Forests
 Vertical stratification
 high rainfall
 most biodiverstiy
 nutrient poor soil due to increased
decomposition of dead organic matter by
bacteria
Desert
 Sparse rainfall (30 cm or less)
 surface temp. above 60 C during the day
 Plants have adaptations to retain water
such as needles, thick waxy cuticle, and
CAM photosynthesis.
Tundra
 High winds and cold temperatures create
alpine tundra plant communities.
 Frozen top layer of soil
 Little annual rainfall
 moose and reindeer graze on the small
plants and lichens
Principle of Allocation
 An organisms organized way of partitioning
energy in order to maintain homeostasis.
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escape from predators
obtaining nutrients
growth
reproduction
homeostasis