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Organisms and Their Environment
Ecology
• Scientific study of interactions among
organisms and their environment.
– Reveals relationships among living and
nonliving
– Interdisciplinary (Math, chemistry, physics,
geology)
Biosphere
Portion of the Earth that supports life.
High in atmosphere to bottom of oceans
Abiotic Factors
• Non-living parts of an organisms environment.
• Air currents, temperature, moisture, light and soil
• Help determine if organism can survive
Levels of Organization
Levels of Organization
• Population-Group of
organisms of one species
that interbreed and live in
the same place at the
same time.
• Community—Collection of
interaction populations.
Ecosystem—Interactions among
populations in a community (physical
surroundings, or abiotic factors)
– Terrestrial ecosystems
• forests, meadows, desert scrub
– Aquatic
• Freshwater (ponds, lakes, and streams)
• Saltwater/Marine (75% Earth’s surface)
Organisms in Ecosystems
• Habitat—Place where an organism lives out its
life.
• Niche—Role and position a species has in its
environment (food, shelter, survives,
reproduces)
Hummingbirds have long beak to get nectar deep in flowers, important
niche, reduces competition.
Relationships
• Symbiosis-Relationship in which there is a close
and permanent association among organisms of
different species.
Commensalism—One species benefits and other
species is neither harmed nor benefits.
Mutualism—Both species Benefit
Parasitism-One organism derives
benefit at the expense of other.
Nutrition and Energy Flow
The producers: AUTOTROPHS
• Organisms that use energy from the sun or
energy stored in chemical compounds to
manufacture their own food.
• auto (Greek) self
• trophe (Greek) nourishing
• Plants, some uni-cellular organisms
The Consumers: Heterotrophs
• Organism that can not make their own food and
must feed on other organisms.
• hetero (Greek) other
• trophe (Greek) nourishing
Types of Heterotrophs
• Herbivore-Heterotrophs that feed only on plants.
– Herba (Latin) grass; vorare (Latin) devour
– Rabbits, grasshoppers, squirrels, bees, elephants
• Carnivore-Animals that kill and eat other animals
– caro (Latin) flesh; vorare (Latin) devour
– lions
– Scavengers (Eat animals already dead; leftovers)
vultures
• Omnivore-Animals that eat both plants and other
animals
– omnis (Latin) all; vorare (Latin) to devour)
– Humans, raccoons, opossums, bears
Decomposer
Organisms that breakdown
and absorb nutrients from
dead organisms.
Fungi, protozoan's, bacteria
Matter and Energy Flow
Food Chain- Simple model used
to show how matter and energy
move through an ecosystem
• Arrow indicates direction which energy is
transferred from one organism to the next.
• Always between 3 and 5 Links (4 shown)
• Amount of energy remaining in fifth link is
only a small portion of what is available at
the first link (lost heat)
Trophic Levels– Feeding Steps
4th Trophic Level
Third-order heterotrophs (carnivores)
Carnivores that feed on second-order heterotrophs
Alligators
3rd Trophic Level
Second-order heterotrophs (carnivores)
Heterotrophs that feed on first-order heterotrophs
Heron that feed on small fish, frogs
2nd Trophic Level
First –order heterotrophs (herbivores)
Feed on autotrophs
Small fish, crustaceans
1st Trophic Level
Photosynthetic autotrophs (Producers)
Trees, grasses, etc.
Sun
Bacteria and Fungi decompose all links in
food chain when organisms die.
Express all the possible feeding
relationships at each trophic level
in a community
Food Web
Ecological Pyramid
• Energy flow through an ecosystem
• Base-autotrophs-first trophic level
• Higher trophic levels are layered on top
of one another.
• Initial source of energy is the sun.
Energy/Population size/Biomass
decrease as trophic levels increase
Each bar represents the population
size within a trophic level.
Each bar represents the amount
of biomass with in trophic level.
Pyramid of Energy
Each bar represents the energy
available within a trophic level
•On average, each feeding level only
contains 10% of the energy as the one
below it
• Loss as heat and organisms
processes
10,000 units (calories) Producers  herbivores
would receive 1000 units primary carnivores
100 units  secondary carnivores 10 units.
Humankind’s Worst Enemy
Which mammal has killed more humans, destroyed more things, and
spread more disease than any other?
You might think the answer is humans, but it’s rats.
Rats destroy a fifth of the world’s food supply. Most rat damage to the
food occurs where there is little food to spare.
The Indian rice destroyed by rats could feed 250 million people a year.
Rats spread disease, including the bubonic plague, which killed a third
of the people in medieval Europe.
All the wars in history have not done as much damage as rats. Surely
rats are peoples worst enemy.
What are some things rats might be good for? This might
take a while.
Cycles in Nature
Water Cycle
Carbon Cycle
Nitrogen Cycle
Phosphorus Cycle
Water Cycle (Hydrologic Cycle)
Water constantly moves between atmosphere and earth.
• Evaporation--A change from liquid to vapor form
(lakes and oceans). Surface water to Atmosphere
• Precipitation--falling products of condensation in
the atmosphere, as rain, snow, or hail.
• Transpiration--The process of giving off vapor
(plants, skin)
Water Cylce
Condensation—Water Vapor to Liquid.
Produces clouds and fog
Run Off—water moves across land. As
flows may infiltrate into the ground,
evaporate into the air, become stored in
reservoirs, or extracted for agricultural and
human uses.
Human Impact on Water
Cycle
• Agriculture
• Alteration of chemical
composition of atmosphere
• Construction of dams\
• Deforestation and afforestation
• Removal of groundwater from
wells
• Water abstractions from rivers
• Urbanization
Carbon Cycle
Exchange of carbon between biosphere,
geosphere, hydrosphere and atmosphere.
• Atmosphere provides Carbon Dioxide
• Autotrophs use carbon dioxide to make
carbon rich molecules (photosynthesis)
• Autotrophs and heterotrophs break down
high energy carbon molecules and release
carbon dioxide as WASTE.
Carbon taken from
atmosphere
• Plants bring in CO2 from atmosphere for
photosynthesis
• Enters through water as oceans near poles
cool and are able to dissolve more C02
Carbon released back into
atmosphere
• Respiration- Endothermic Reaction; Breaks
down glucose into CO2 and water.
• Decay of Animal and Plants ( Decomposers
break down carbon molecules and convert
into CO2)
• Combustion of organic materials- Burning
fossil fuels (coal, petroleum, natural gas)
• Limestone Reactions- (calcium
carbonate) Breaks down into CO2
• Warmer water releases CO2
Carbon Recap
• Autotrophs use CO2 from air to make
organic molecules
• Carbon transferred to heterotrophs when
eat plants; uptake by decomposers
• Most carbon back into air through
respiration
• Dead organic matter incorporated into
land.
Nitrogen Cycle
Transfers nitrogen and nitrogencontaining compounds
• Earth atmosphere is 78% Nitrogen.
• Essential for amino acids; nucleic acids;
photosynthesis.
• Lightning and bacteria convert nitrogen
from air into usable form-Nitrogen Fixation
• Plants use nitrogen to make proteins.
• Herbivores eat plant proteins and convert
to animal proteins.
• Animal urine returns nitrogen to soil.
• Plants reuse
• Bacteria return to air.
Phosphorus Cycle
• Moves between living and non-living
things
• Required for growth and development
• Plants obtain phosphorus from soil.
• Animals obtain phosphorus from eating
plants.
• Short-term and Long-Term Cycles
Short-Term phosphorus cycle
Animals eat plants
with phosphorus
Animals die;
phosphorus returned
to soil
Plants get
Phosphorus
from soil
Long-term phosphorus cycle
Phosphorus washed
into oceans
Phosphorus
incorporated
into limestone
Insoluble compound
Rocks erode
and disintegrate;
part of ecosystem