Download Populations and Ecosystems

Populations and Ecosystems
Ecosystem- includes all of the living things (plants, animals
and organisms) in a given area, interacting with each other,
and also with their non-living environments (weather, earth,
sun, soil, climate, atmosphere).
Ecology- the branch of biology dealing with the relations and
interactions between organisms and their environment
Biodiversity – the degree of variation of life. Variety of
organisms present in different ecosystems.
Plants and animals need air, water, light (plants only), space,
food and shelter…
these things can be found in their environment.
● Population - all the individuals of a given species in a
specific area or region at a certain time.
● Community - refers to all the populations in a specific area
or region at a certain time.
● Environment – the surroundings or conditions in which an
organism operates.
● Habitat – the natural surroundings or environment in which
an organism lives
Biotic and abiotic factors make up
an ecosystem…
● Biotic Factor – are all the living organisms within an
ecosystem
● Abiotic Factor – are all of the non-living things in an
ecosystem (ex: pH, sunlight, turbidity, available nutrients,
wind, etc.)
What is a niche?
● Niche - the status of an organism within its environment
and community (affecting its survival as a species). It
includes:
● The role a species has in its environment
● Its interactions with the biotic and abiotic factors of its
environment
Coexistence and Competition
● Competition – occurs when a resource that is essential to
growth and reproduction occurs in short supply. It is an
interaction that has a mutually negative effect on the
participants.
● Coexistence – occurs when populations of several species
that utilize the same limiting resources manage to persist
within the same area.
Population Density
● It is a measure of the number of organisms that make up a
population in a defined area.
● What is its significance?
● Ecosystems function best when they have the correct number
of organisms making up a population to utilize the resources
available.
● Ideal number of a population = carrying capacity
● Population density = Population / Total land area
Limiting Factors
● Environmental factors that limit population sizes in a
particular ecosystem.
● Examples:
● Food/nutrients
● Temperature
● Water
● Natural Resources
● Predation
Density Dependent Factors
● Any factor limiting the size of a population whose effect is
dependent on the number of individuals in the population.
● Ex: Disease having a greater effect in limiting the growth of a
large population, since overcrowding facilitates its spread.
Density Independent Factors
● Any factor limiting the size of a population whose effect is
not dependent on the number of individuals in the
population.
● Ex: Earthquake, impacts all members of a population
regardless of whether the population is large or small.
8.L.3.2 Summarize the relationship among producers, consumers and decomposers, including the positive and negative
consequences of such interactions including:
Coexistence and cooperation
Competition
Parasitism
Mutualism
● Three categorizes of the food chain:
● Producers
● Consumers
● Decomposers
They are
dependent on
each other!!!
Producers
● Producers get their food and energy from the sun.
● Plants
● They make their food through a process called
photosynthesis
Consumers
● Consumers need to eat their food to get energy
● Animals
● Three Types:
● Carnivores
● Herbivores
● Omnivores
What type are humans?
Consumer:
Carnivores
● Only eat meat (other animals)
Consumer:
Herbivores
● Herbivores only eat plants
Consumer:
Omnivores
● Omnivores eat both meat (animals) and plants
Decomposer
● Decomposers eat dead things and turn them back into dirt,
or soil.
● Ex: Mushrooms, worms, bugs
Symbiotic Relationship
● Symbiosis – interaction between two species.
Sometimes beneficial, sometimes harmful…
There are a few types:
● Commensalism
● Mutualism
● Parasitism
Commensalism
● Commensalism - an association between two organisms
in which one benefits and the other derives neither benefit
nor harm.
Mutualism
● Mutualism - symbiosis that is beneficial to both organisms
involved.
Parasitism
● Parasitism - one species, the parasite, benefits at the
expense of the other, the host.
8.L.3.3 Explain how the flow of energy within food webs is interconnected with the cycling of matter
(including water, nitrogen,
carbon dioxide and oxygen).
Flow of energy
● What is the ultimate source of energy?
● The sun!
The flow of energy through ecosystems can be described and
illustrated in food chains, food webs, and pyramids (energy,
number, and biomass).
● Food Pyramid
Food Chain
● Food chain – linear sequence of links in a food web
starting from "producer" species (such as grass or trees)
and ending at apex predator "decomposer" species (like
grizzly bears or killer whales).
● Simple
● Why are there fewer organisms at the top of the food
chain?
Food Web
● Food web - a system of interlocking and interdependent
food chains.
● More complex
● Interconnected
Energy Pyramid (Trophic Pyramid)
● Energy Pyramid – graphical model of energy flow in a
community.
● Producers are at the bottom because they are able to transform
the sun’s energy into a large amount of plant energy through
photosynthesis.
● Animals that eat plants are at the next level (primary consumers).
They reply on plants for their energy.
● Animals that eat primary consumers are next (secondary
consumers). They reply on primary consumers for most of their
energy. The energy level of this section of the pyramid is smaller
because most of the energy at the primary consumer level is used
for their life processes and transformed to heat before these
animals are consumed.
● Animals that eat secondary consumers make up the next level
(tertiary consumers). They reply on secondary consumers for
most of their energy. This energy level of the pyramid is even
smaller than the others.
Energy Pyramid
● How much energy is lost from one level to the next?
● 10 % of the original energy is left to feed the next level. 90 %
of the available energy is used for life processes such as
respiration, photosynthesis, and reproduction and
transformed to heat energy before an organism is consumed.
● The amount of energy at each trophic level decreases as it
moves through an ecosystem.
Cycling of Matter
● The flow of energy is interconnected with the cycling of
matter.
● Matter, in the form of nutrients, also moves though the
organisms at each level. But matter cannot be replenished
like the energy from sunlight. The atoms of carbon,
nitrogen, oxygen and other elements make up the bodies
of organisms alive today are the same atoms that have
been on Earth since life began.
● Matter is constantly recycled.
Cycling of Matter
● Flow of energy within food webs is interconnected with the
cycling of matter including…
● Water
● Nitrogen
● Carbon Dioxide
● Oxygen
Cycling of Water
Cycling of Nitrogen
● Nitrogen cycle – how nitrogen moves between plants,
animals, bacteria, the atmosphere, and soil in the ground.
● For nitrogen to be used by different life forms on Earth, it
must change into different states.
Nitrogen in the air, N2, nitrates (N03), nitrites (NO2), and
ammonium (NH4).
●
The most important part of the cycle is bacteria.
Bacteria helps nitrogen change between states so it can be
used.
● Fixation - Fixation is the first step in the process of making
nitrogen usable by plants. Here bacteria change nitrogen into
ammonium.
● Nitrification - This is the process by which ammonium gets
changed into nitrates by bacteria. Nitrates are what the plants
can then absorb.
● Assimilation - This is how plants get nitrogen. They absorb
nitrates from the soil into their roots. Then the nitrogen gets
used in amino acids, nucleic acids, and chlorophyll.
● Ammonification - This is part of the decaying process. When a
plant or animal dies, decomposers like fungi and bacteria turn
the nitrogen back into ammonium so it can reenter the nitrogen
cycle.
● Denitrification - Extra nitrogen in the soil gets put back out into
the air. There are special bacteria that perform this task as well.
Cycling of Carbon Dioxide
● Carbon Cycle – cycles describing the flow of essential
elements from the environment to living organisms and
back to the environment again.
● All living things are made of carbon. Carbon is also a part
of the ocean, air, and even rocks.
● Because the Earth is a dynamic place, carbon does not stay
still. It is on the move!
Oxygen Cycle
● Almost all living things need oxygen. They use this oxygen
during the process of creating energy in living cells.
● Plants mark the beginning of the oxygen cycle. Plants are able
to use the energy from the sun to convert carbon dioxide and
water into carbohydrates and oxygen into a process called
photosynthesis.
● Animals form the other half of the cycle, we breathe in O2 which
we use to break carbohydrates down into energy in a process
called respiration. CO2 produced during respiration is
breathed out by animals into the air.
● http://northsaanich.sd63.bc.ca/pluginfile.
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