biology: the study of life “bio”- living, life “logos”- knowledge/study 1
TRANSCRIPT
Biology: The Study of Life
“Bio”- living, life
“Logos”- knowledge/study
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Human Impact: Humans are members of the Biosphere
Biosphere
Entire portion of planet where life occurs
from the upper atmosphere to ocean floor and below
Ecosystem
Consists of all the organisms living in a particular area (plants, animals, bacteria) as well as all the nonliving, physical components of the environment with which the organisms interact (air, soil, water, sunlight)
Ex: marsh, forest, mountain lake, desert 3
Organization of the Biosphere
Many types of ecosystem
Tundra
Tropical rainforests
Deserts
Kelp forests
Coral reefs4
Organization of the Biosphere
Major determinant of which ecosystem is found where is climate
Deserts = low rainfall
Tropical rainforests = wet & warm
Coral reefs = shallow, clear warm oceans
Reefs and tropical rainforests are both homes to wide diversity of organisms
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Within an Ecosystem:Community: All living organisms in an ecosystem
Organisms in communities interact with one another and are often strongly dependent upon one another (form food webs, etc)
Population: All members of same species which may mate with one another within an area
Many populations in one community
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Ecosystems are dynamic environments
Organisms exchange materials and energy with their environment
Energy and nutrients are cycled through
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Ecosystems are characterized by:
Cycling of materials
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How do humans impact this?
Ecosystems are characterized by:
Flow of energy
Food chains
Food webs
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How do humans impact this?
Human PopulationHuman activities shape ecosystems
cut down forests
plow grasslands
drain marshes
build houses and roads
Redirect water
Activities often result in pollution that changes ecosystems
Effects are particularly bad in rainforest and coral reefs
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Human PopulationHuman activities have
Destroyed > 10% of coral reefs and damaged another 30%
Cut down rainforests
Polluted water
Harming ability of world’s ecosystems to support us, our children and other species
Just starting to realize how strongly we depend on our ecosystems
We may be changing our planet in unforeseen, negative ways 11
BiodiversityBiodiversity = number of species, and their genetic variability
Between 2 and 20 million species alive today
Human activities threaten many of them
Hundreds of species go extinct every day
Many more have been reduced to a very small number of individuals
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BiodiversityEach individual has only two sets of chromosomes
Each can carry only 2 copies of the gene for any trait
Fewer individuals = less genetic diversity
Natural selection acts on diversity
If individuals don’t have needed traits to survive in environment, all will die
Fewer genetic options = more likely extinction is as environment changes
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Biodiversity
Loss of species and loss of genetic diversity in today’s ecosystems is worrying
Are human activities leading to a “mass extinction” like the one 65 million years ago when the dinosaurs all died?
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