Transcript Chapter 3: The Biosphere

Chapter 3: The Biosphere
Ecologists study the Biosphere…
What is Ecology?
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Ecology is the scientific study of
interactions among organisms and
between organisms and their own
environment, or surroundings.
Ecology comes from the Greek word
”oikos” meaning house. It is also the root
word for economy.
Nature’s houses come in many sizes-from single cells to
entire planets.
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Biosphere-the combined portions of the planet in which
all life exists, including land, water and air, or
atmosphere. It is the largest of nature’s houses.
Facts about the biosphere:
1. It extends from about 8 km above Earth’s surface to
as far as 11 km below the surface of the ocean.
2. Interactions within the biosphere produce a web of
interdependence between organisms and the
environment in which they live.
Levels of Organization:
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Species-a group of organisms so similar to one another
that they can breed and produce fertile offspring.
Populations-groups of individuals that belong to the
same species and live in the same area.
Communities-assemblages of different populations that
live together in a defined area.
Ecosystem-a collection of all the organisms that live in a
particular place, together with their nonliving, or
physical, environment.
Biome-a group of ecosystems that have the same
climate and similar dominant communities.
Work of Ecologists…
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Individual ecologists study all of these, except for the
biome, which is so large that a group or team of
ecologists examine it together.
The highest level of organization studied by ecologists is
the biosphere.
Ecologists utilize a wide range of tools and techniques to
study the living world such as binoculars, field guides,
DNA studies, radio tags, or other data.
Ecological research is conducted via three basic
approaches: observing, experimenting, modeling.
Energy Flow
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Sunlight is the main source of energy for life on Earth.
Some types of organisms may depend on energy stored
in inorganic chemical compounds.
Autotrophs-organisms that utilize energy from the
environment to fuel the assembly of simple inorganic
compounds into complex organic molecules. Ex. Plants,
some algae, and certain bacteria.
Producers-make their own food and are essential to the
flow of energy through the biosphere.
A producer may capture energy from
sunlight, or capture chemical energy.
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Photosynthesis-a process in which
autotrophs utilize light energy to power
chemical reactions that convert carbon
dioxide and water into oxygen and sugar.
Chemosynthesis-a process in which
organisms utilize chemical energy to
produce carbohydrates.
Who are the main autotrophs on
land?
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Plants
Who are the main autotrophs in
ecosystems and in the sunlit upper
layers of the ocean?
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algae
Heterotrophs are organisms that rely on
other organisms for their food supply.
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Types of heterotrophs:
Herbivores-obtain energy by eating only plants.
Carnivores-eat other animals.
Omnivores-eat both plants and animals.
Detrivores-feed on plant and animal remains and
other dead matter collectivley called detritus.
Decomposers-break down organic matter.
Examples of heterotrophs
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Herbivores-cows, deer, caterpillars
Carnivores-snakes, dogs, owls
Omnivores-humans, bears
Detrivores-mites, snails, earthworms,
crabs
Decomposers-bacteria, fungi
What happens to the energy in an ecosystem
when one organism consumes another?
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Energy flows through an ecosystem in one
direction, from the sun or inorganic compounds
to autotrophs (producers) and then to various
heterotrophs (consumers).
The energy stored by producers can be passed
through an ecosystem along a food chain.
Energy Use
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Food chain-a series of steps in which organisms
transfer energy by eating and being eaten.
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FOOD CHAIN
(just one path of energy)
Food Web-develops when the feeding relationships among
the various organisms in an ecosystem form a network of
complex interactions.
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FOOD WEB
(everything is connected!)
Trophic level-each stepin a food chain
or a food web.
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Producers comprise the first trophic level.
Consumers make up the second, third, or
higher trophic levels.
Ecological pyramid-a diagram portraying
the relative amounts of energy or matter
contained within each trophic level in a
food chain or food web.
Three types of ecological pyramids:
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Energy pyramid
Biomass pyramid
Pyramid of numbers
*Only part of the energy that is stored in one
trophic level is passed on to the next level. Only
about 10% of the energy is available within one
trophic level.
Biomass-the total amount of living tissue within
a given trophic level.
Cycles of Matter
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Read paragraph #1 on page 74.
Matter is recycled within and between ecosystems.
Biogeochemical cycle-process in which elements,
chemical compounds, and other forms of matter are
passed from one organism to another and from one part
of the biosphere to another.
Matter can cycle through the biosphere because of the
law of conservation of matter.
Also read paragraph #3 on page 74.
Cycles in the biological systems
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The Water Cycle:
Water moves between the ocean, atmosphere, and land.
Water is cycled in the following manner:
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Evaporation-process where water changes from liquid to
form an atmospheric gas. (Water may also enter the
atmosphere by evaporating from the leaves of plants in
the process of transpiration).
Condensation-clouds.
Precipitation-hail, rain, sleet, or snow.
Nutrient Cycles
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Nutrients-all the chemicals that an organism needs to
sustain life.
How do primary producers obtain nutrients? Primary
producers such as plants obtain nutrients in simple
inorganic forms from their environment.
How do consumers obtain nutrients? Consumers obtain
nutrients via consuming other organisms.
Carbon, nitrogen, and phosphorus are all part of this
nutrient cycle.
The Carbon Cycle
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The recycling of carbon dioxide, CO2.
Carbon dioxide is taken in by plants during
photosynthesis and given off by both
plants and animals during respiration.
Four main types of processes that move carbon through the carbon
cycle:
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1. Biological processes (e.g. photosynthesis and respiration).
2. Geochemical processes (e.g. erosion and volcanoes).
3. Mixed biogeochemical processes (e.g. burial and decomposition
of dead organisms and their conversion under pressure to coal and
petroleum).
4. Human activities (e.g. releasing carbon dioxide into the
atmosphere and burning forests).
The Nitrogen Cycle
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All organisms require nitrogen to make amino acids, which are
utilized to build proteins.
Nitrogen gas comprises 78% of Earth’s atmosphere.
Only certain forms of bacteria can directly utilize nitrogen.
Nitrogen fixation-process where nitrogen gas is converted into
ammonia in order for producers to be able to utilize the products of
nitrogen (nitrites and nitrates).
Denitrification-process of converting nitrates into nitrogen gas;
releases nitrogen into the atmosphere once again. Consumers eat
producers and reuse the nitrogen to make their own proteins. Once
an organism dies. Decomposers return nitrogen to the soil as
ammonia.
The Phosphorus Cycle
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Phosphorus forms part of the nucleic acids, DNA and RNA. It is not
a part of the biosphere and does not enter the atmosphere. Here,
phosphorus is recycled. Organic phosphate moves through the food
web, from producers to consumers.
Summary
The Nitrogen Cycle
Summary
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Matter is recycled through producers, consumers, and decomposers.
Energy is passed on and exchanged up the food chain.
Nutrient limitation:
Primary productivity-the rate at which organic matter is created by
producers. A factor controlling the primary productivity of an
ecosystem is the amount of available nutrients.
Limiting nutrient-substance that is scarce or cycles slowly. Because
of limiting nutrients, farmers apply fertilizers to their crops in order
to boost productivity.
Fertilizers contain three important nutrients: nitrogen, phosphorus,
and potassium. In the ocean, nitrogen is often the limiting nutrient.
Algal bloom-result of an aquatic system receiving a large input of a
limiting nutrient when an immediate increase in the amount of algae
and other producers occurs.