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Biotic vs. Abiotic Factors
– Biotic = living (plants, animals, bacteria, fungus, protists)
– Abiotic = non-living (temp, water, soil, weather, rocks, sunlight, etc)
Ecological Organization
– Organism ~ one member of one species– Population ~ all members of one species in a given
area– Community ~ all populations in a given area– Ecosystem ~ all members of community plus
abiotic factors in the area– Biome ~ group of ecosystems with same climate
and organisms
Succession– Primary Succession = colonization of NEW land by
pioneer species until a climax community is reached. • Lava flow lichens mosses grasses shrubs
trees
– Secondary Succession = existing community is destroyed and a new one begins to form• Occurs more quickly than primary succession because
soil is already present and seeds were left behind• Forest Fire mosses grasses shrubs trees
Ecosystem Relationships– Niche vs. Habitat
• If an organism’s habitat is its address, its niche is its occupation.
– Competition• Organisms of same or different species try to use same
resource at same place during same time.• Competition can be reduced by developing different
niches.• Ex. 3 species can easily live in same tree if one eats
leaves, one eats bark and another eats the flowers.
– Predator-Prey• Organism doing killing = predator• Organism being killed = prey
Symbiosis• Mutualism – both species benefit from the relationship–Flowers may feed on insects, which may in turn
disperse pollen to other flowers• Commensalism – one species benefits and the other is
unaffected by the relationship–Barnacles attach to the skin of a whale to catch more
food particles• Parasitism – one species benefits and the other is
harmed by the relationship–Tapeworms live inside a human intestine and feed
from the human
Energy Flow– Producers (autotrophs)• Use sunlight to make their food and energy through
photosynthesis or chemosynthesis• Only plants and some bacteria/algae are autotrophic
– Consumers (heterotrophs)• Must acquire their energy from other organisms• Herbivores = eat plants only• Carnivores = eat animals only• Omnivores = eat both plants and animals• Scavengers = eat dead or decaying plants and animals• Decomposers = break down dead or decaying plants or
animals
Feeding Relationships
• Food Chains = series of steps in which organisms transfer energy by eating and being eaten–Arrow shows the direction of energy transfer in
the food chain–Ex. Grass Grasshopper Mouse Snake
Hawk
Trophic Levels
–Producers – get energy from sun & use some for own metabolism–Primary Consumers – get 10% of original energy
from producers and use some for own metabolism–Secondary Consumers – get 10% of energy from
primary consumers and use some for own metabolism–Tertiary Consumers – get 10% of energy from
secondary consumers and use some for own metabolism
Populations
– Population Growth• If birth rate is larger than death rate = growing• If birth rate is smaller than death rate =
shrinking• Immigration = movement into a population• Emigration = movement out of a population
Populations
– Exponential Growth (J-shaped Curve)• Occurs when individuals reproduce at a
constant rate (ex. every individual has 2 kids)• Will occur under ideal conditions with
unlimited resources
Populations– Carrying Capacity (S-shaped Curve)• A population’s growth slows or stops following
a period of exponential growth• Carrying capacity = largest number of
individuals that a given environment can support
Populations– Limiting Factors• A factor that causes a population’s growth to
decrease• Competition, predation, disease, climate extremes,
human disturbance– Density-dependent vs. Density-independent• Density-dependent = limit a population according to
population size–Competition, predation
• Density-independent = affects all populations the same, regardless of size–Natural disasters
Human Environmental Impacts
– Human population is growing exponentially with no slowing in sight because of technological advances in medicine.
– Humans are clearing habitats of plants and animals to have more room for cities & suburbs as well as space to grow more food for the growing populations.
Human Environmental Impacts
• Ozone depletion–Ozone protects us from harmful UV
radiation from the sun–Chlorofluorocarbons (CFCs) destroy the
ozone layer–CFCs are banned, but their affects are lasting
as the ozone layer slowly heals itself
Human Environmental Impacts
• Global Warming–Burning of fossil fuels adds excess carbon
dioxide in the atmosphere–Carbon dioxide is an insulator and traps heat
in the atmosphere causing the global temperature to slowly rise.–Higher global temperatures could have
devastating effects such as melting of glaciers and changes in weather patterns.
Human Environmental Impacts• Pesticide Use–DDT and other pesticides are dangerous because they
can contaminate groundwater and other water sources.–Biological magnification – concentrations of a
harmful substance increase in organisms at higher trophic levels in a food web or a food chain.»Ex. algae pick up toxin from water they live in –
plankton eat much algae to survive – small fish eat the plankton – large fish eat the large fish there is much more DDT in the large fish than the plankton because it has concentrated up the food chain.
Practice Questions1. Which situation would result in the greatest
increase in the human population?
A. decreased birth rate and increased death rate
B. increased infant mortality and decreased death rate
C. decreased death rate and increased birth rate
D. increased birth rate and increased infant mortality
2. In a forest ecosystem, which is an abiotic
factor?
E. the amount of rainfallF. the size of the deerG. the type of treesH. the number of birds
3. In the carbon cycle, atmospheric carbon dioxide is converted into organic material by which process?
A. cellular respirationB. decompositionC. photosynthesisD. transpiration
4. Why do ecosystems rarely contain more
than a few trophic levels?
E. Energy transfer efficiency is high.F. Energy transfer efficiency is low.G. Energy amounts remain constant.H. Energy cannot flow through levels.
Practice Questions5. Recent climate data suggests a global
warming trend. The most likely cause could be an increase in which gas?
A. oxygenB. carbon dioxideC. nitrogenD. hydrogen sulfide
6. Silt and nutrients from eroding farmland
flow into a lake. As a result, which will most likely increase first?
E. fish populationF. shore vegetationG. algae growthH. dissolved oxygen
7. A community is studied and several interactions are observed and recorded.
Which type of interaction could illustrate the process of mutualism?
A. interaction AB. interaction BC. interaction CD. interaction D