the biosphere - mrs. griffin's science...
TRANSCRIPT
What is the Biosphere?
• Combined portions of
the planet in which all
of life exists,
including land, water
and atmosphere
• Extends from 8-km
above Earth’s surface
to 11-km below the
surface of the ocean.
Levels of Organizations
• Species
– Group of organisms so
similar to one another that
they can breed and
produce fertile offspring
• Population
– A group of individuals that
belong to the same species
and live in the same area
• Community
– All the different populations
that live together in a defined
area
• Ecosystem
– Collection of all the organisms
that live in a particular place,
together with their nonliving
environment
• Biome
– A group of ecosystems that
have the same climate and
dominant communities
Ecosystems
• Influenced by a
combination of
Biological and
Physical Factors
• Depend on biotic
factors and abiotic
factors
Biotic vs. Abiotic
• Biotic Factors
– The biological influences
on organisms within an
ecosystem
– Ex: birds, trees,
mushrooms, and bacteria
• Abiotic Factors
– Physical or nonliving
factors that shape
ecosystems
– Ex: temperature,
precipitation, humidity,
wind, nutrient
availability, soil type,
and sun light
What are the Major Land Biomes?
• Tropical Rain Forest
• Temperate Forest
• Taiga
• Savanna
• Temperate Grassland
• Chaparral
• Desert
• Tundra
• Mountain
How are Biomes Named?
• According to their
plant life
• Plant life
determine which
organisms live
there
Organisms in Biomes
• Plants & animals
have adapted to
specific
environments
• Threatened by
human activities
Freshwater Ecosystems
• Includes lakes, ponds,
rivers, streams and
wetlands
• Distinguished by:
– Depth of the water
– How fast the water
moves
– Availability of mineral
nutrients, sunlight, and
oxygen
Marine Ecosystem
• Identified by the
presence of salt
water
• Includes estuaries,
coral reefs, oceans
and ice caps
What is Biodiversity?
• Term used to
indicate the number
and diversity of
species on Earth
• There are now an
estimated 13 million
species of living
organisms
Why is Biodiversity important? • Earth’s greatest natural
resource
• Species of many kinds
have provided us with:
– Food: beef, chicken,
salad
– Industrial Products:
paper, rubber
– Medicines: painkillers,
antibiotics, anticancer
drugs
What effects Population?
•Limiting factors are
resources or other factors
in the environment that
can lower the population
growth rate.
•The carrying capacity (K) is
the maximum population
size that can be supported
in a particular area without
destroying the habitat.
Limiting Factors •Limiting factors include a low food supply and a lack of
space.
•Limiting factors can lower birth rates, increase death
rates, or lead to emigration.
Carrying Capacity
•Limiting factors determine the carrying capacity of a
population.
•When organisms face limiting factors, they show logistic
growth.
•When there are no limiting factors, the population grows
exponentially.
Genetic Diversity •The total number of genetic characteristics in a
given population
•These variations serve as a way for a population
to adapt to changing environment.
•Greater variation increases the chance that
some individuals of that population will possess
variations that are suited to the new
environment.
–They’ll live and pass on those traits to the
next generation, preventing extinction of their
species!
Imagine:
•One individual has a mutation that makes it darker color
than the rest of the population.
•After a volcanic eruption, so the cover is no longer pale
yellow, but a dark.
•The darker individual will then survive in the new
environment and reproduce more than the other
individuals, passing on “dark color” genes to the next
generation.
Variation in an Ecosystem
•Every organism has a role
to play in its environment.
•This role, which includes
where it lives in the
environment, what it uses,
what it eats, and who eats
it, is called its niche.
•No two species can ever
share the SAME niche.
Variation in an Ecosystem
•When a species is lost in a
diverse ecosystem, then
another species may take
over its role…
•Or all the organisms that
depend on it may die if
there is not a diversity of
organisms already in that
ecosystem.
•But it takes a LONG time.
How can humans reduce biodiversity?
• Altering habitats
• Hunting species to
extinction
• Introducing toxic
compounds into food
webs
• Introducing foreign
species to new
environment
Loss of Biodiversity
•The greatest threat to biodiversity is habitat loss.
•Habitats (places where organisms live) are “lost” due to
land use changes
–Agriculture
–Urbanization
Habitat Alteration
• When land is developed,
natural habitat may be
destroyed
• Habitats supply
organisms what they
need
• Habitat destroyed means
that organisms will die
• Ex: Florida Panther
Introduced Species
• Invasive Species
– Non-native animals that
thrive in new territory
where they are free of
predators, diseases, or
resources limitations that
may have controlled
their population in their
native habitat
• Can cause the extinction
of native species
• Ex: Pythons in Florida
Extinction
• Occurs when a species
disappears from all or part
of its range
• Caused by habitat
destruction, introduced
species, and hunting
• Endangered Species
– If a species numbers have
fallen so low that it is likely
to become extinct
Endangered Species Act
• Began in 1973
• Protect plants and
animals near extinction
• Protect the land where
the organism lives
• Helps to increase
populations that are in
danger of extinction
Nutrient Cycles
• https://www.youtube.com/watch?v=A98S-BqP4Po
•A biogeochemical cycle is a pathway by which a
chemical substances moves through both biotic
(biosphere) and abiotic (lithosphere, atmosphere, and
hydrosphere) compartments of Earth.
•Water, for example is recycled through the water cycle
The Carbon Cycle
•Carbon is one of the most common elements found in
living organisms. Carbon is constantly cycling between
living organisms and the atmosphere through:
–photosynthesis
–cellular respiration
–burning of fossil fuels.
•Global Climate Change
occurs when more carbon
dioxide, a greenhouse
gas, is released into the
atmosphere than can be
used for photosynthesis.
The Nitrogen Cycle •Nitrogen is one of the most common elements in living
organisms. It is important for creating proteins and
nucleic acids, like DNA.
•The air that we breathe is mostly nitrogen gas, but
unfortunately animals and plants cannot use the
nitrogen when it is a gas.
–In order for plants to make use of nitrogen, it must
be transformed into molecules they can use by:
lightning, nitrogen fixation by bacteria, or
decomposition.
–Nitrogen can be turned back into a gas by bacteria
through denitrification.
The Nitrogen Cycle •Humans cause acid rain by burning fossil fuels
releasing nitrogen gasses into the atmosphere.
Energy Flow
•Ecosystems maintain themselves by cycling nutrients and
transferring energy.
•Most ecosystems depend on sunlight as the main energy
source. The first step trophic level uses solar energy to
produce chemical energy through photosynthesis. On
average, only about 10 percent of net energy produced at
one trophic level is passed on to the next.
What Eats What in an Ecosystem
• Producers
– Makes its own food
– Plants, trees, algae
• Consumers
– Gets energy by eating
other organisms
– Animals
• Herbivore
– Eats only producers
– Cows, sheep, deer,
grasshoppers
• Carnivores
– Eats only other
consumers
– Lions, hawks, spiders
• Omnivore
– Eats both producers and
consumers
– Bears, pigs, humans
What is a Food Chain
• A sequence in which
energy is transferred
from one organism to
the next as each
organism eats
another
What is a Food Web?
• A group of
interrelated food
chains
• No one path
• Shows feeding
relationships in an
ecosystem