Living Things! Factors that affect living things are: Biotic factors – things that are alive or...
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Living Things! Factors that affect living things are: Biotic factors – things that are alive or were alive (other organisms) Abiotic factors – things that are non-living (temperature, water etc.) The interaction of all biotic and abiotic factors creates an ecosystem. 1
Living Things! Factors that affect living things are: Biotic factors – things that are alive or were alive (other organisms) Abiotic factors – things that
Living Things! Factors that affect living things are: Biotic
factors things that are alive or were alive (other organisms)
Abiotic factors things that are non-living (temperature, water
etc.) The interaction of all biotic and abiotic factors creates an
ecosystem. 1
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2 The branch of biology that studies the way living things
interact with each other and with their physical environment. It
looks at the ways an organism is affected by its surroundings and
how the environment is affected by the presence and activities of
the organisms. Ecology
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Roles of Organisms Organisms can be either producers, consumers
or decomposers (detritivores) in terms of energy flow through an
ecosystem. 8 All living things need energy to survive and grow. The
source of this energy is the sun. Plants through photosynthesis (an
endothermic process) create food (sugar), to store energy for later
use. To release stored energy from the sugar the plants carry out
respiration ( an exothermic process). Not all organisms can produce
their own food, so some must depend on other organisms as a source
of food (energy).
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Producers: are self feeding organisms (autotrophs) that make
organic molecules (glucose) during the process of photosynthesis.
Photosynthesis uses energy from the sun plus the inorganic
molecules CO 2 and H 2 O. Examples: Algae, grasses, trees, etc.
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Consumers: are heterotrophs, organisms that cannot make their
own food, they depend on other living organisms for food. Primary
Consumers: Herbivores that each vegetation Ex. : Grasshoppers,
rabbits, snails, etc. Secondary Consumers: Carnivores that eat the
herbivores Ex. : cats, ladybugs, foxes, owls, etc. Tertiary
Consumers: Top carnivores. Ex. : Lions, bears, wolves, etc. 10
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The Decomposers (Detritivores) : They decompose dead organic
material or wastes to return essential nutrients to the soil. These
nutrients help plants grow. Ex. : Bacteria and mushrooms 11
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Trophic (feeding) level refers to the organisms position in the
food chain Autotrophs are at the base (first trophic level).
Organisms that eat autotrophs are called herbivores or primary
consumers (second trophic level). An organism that eats herbivores
is a carnivore and a secondary consumer. (third trophic level) A
carnivore that eats a carnivore that eats a herbivore is a tertiary
consumer (forth trophic level). Omnivores eat both animals and
plants. 12
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Example of a food chain and the associated trophic (feeding)
levels OrganismsGrassesGrasshopperLadybugRavenMushrooms Bacteria
TypeProducer (plants) Primary Consumer (herbivore) Secondary
Consumer (carnivores) Teriary Consumer (top carnivore) Decomposer
Trophic Levels FirstSecondThirdFourthFeed off all levels 13
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Organism Classification Consumer levelTrophic levelFood source
Plants ------------------First------------------ Herbivoresprimary
Second plants Carnivores secondary or higher (top) Thirdanimals
Omnivoresall levels plants & animals
Detritivores--------------- ---------------- detritus 14 An
overview of Trophic and Consumer levels
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Food Chains and Webs 15
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Food Chains 16
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Energy and Nutrient Flow Through the Ecosystem The movement of
energy is shown by the dark arrows. The movement of the inorganic
nutrients is shown by the open arrows 18
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Food Chains and Webs A food chain is the path of food from a
given final consumer back to a producer. (The arrow points to the
consumer.) grass grasshopper mouse snake hawk Identify the
autotrophs and heterotrophs, and classify each as a herbivore,
carnivore, etc. 19
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Food Webs 21 Identify the autotrophs and heterotrophs, and
classify each as a herbivore, carnivore
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The real world is more complicated than a simple food chain. A
more realistic depiction of who eats whom is called a food web
which depicts interlocking food chains. 22
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Questions to answer From the previous slide identify: 1.
Producers 2. Primary consumers 3. Secondary consumers 4. Tertiary
consumers 5. Top carnivores 23
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ENERGY At each level of the food chain, about 90% of the energy
consumed is lost in the form of heat. The total energy passed from
one level to the next is only about one-tenth of the energy
received from the previous level organism. As you move up the food
chain, there is less energy available to pass on to the next level.
As you move up the food chain animals get larger and need more food
to meet their energy needs. 24 NOTE!! Each organism in the food
chain is only transferring one-tenth of its energy consumption to
the next organism.
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To summarize 1.The ultimate source of energy (for most
ecosystems) is the sun. 2.The ultimate fate of energy in ecosystems
is for it to be lost as heat. 3.Energy and nutrients are passed
from organism to organism through the food chain as one organism
eats another. 4.Decomposers remove the last energy from the remains
of organisms and release nutrients back into the soil. 5.Inorganic
nutrients are cycled, energy is not. 25
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Ecological Pyramids: represent graphically the structure of an
ecosystem Pyramid of Energy Flow : shows the energy that flows
through each trophic level; notice that there is less energy at
each higher level. 27
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Pyramid of Numbers: shows the actual size of populations.
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Pyramid of Biomass: measures the biomass ( g/m ) of the
organisms in a food chain (dry mass). 33
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Feeding the human population is big business (effort and
monetary) To prevent crops from being eaten by insects, agriculture
has turned to various chemicals that kill the insects or that
interfere with their life-cycle (reproduction) In small doses,
these chemicals are not harmful to other organisms, however, when
they enter the food chains and move to high trophic levels, the
quantities accumulate and can cause harm. 36
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Bioamplification (Bio-magnification): Accumulation of toxins in
a food chain so that the major effects are found in the food
predators. Example: DDT: a pesticide used in the 50s and 60s to
control populations of body lice, fleas and mosquitoes). Later used
as a crop pesticide, after which sign of trouble appeared!!!!!
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DDT- Belugas- St. Lawrence River 38
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Worlds Biomes 41
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42 All the Earths ecosystems make up what is called the
ecosphere or biosphere Climate is the main factor that determines
whether a given species will thrive in an area. Biologists have
divided the terrestrial (land) portion of the biosphere into biomes
(collection of ecosystems that are similar) Biomes are large
regions with a distinct climate and specific life forms Each biome
is made up of many ecosystems with communities adapted to varieties
in soil, climate and other factors throughout the biome.
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Biodiversity: the genetic diversity, species diversity and
ecological diversity that are important to life on this planet. It
is the results of adaptations in organisms that have developed over
billions of years in response to: *the variety of environments
found on earth *competition amongst organisms for resources 45
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A Population Group of organisms of the same species living in
the same place at the same time Individuals may come and go, but
the population can remain the same Ex: The flamingos of Lake
Victoria in Africa. Assembled for yearly migration. 48
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In a food web, each organism survives by gaining energy from
the trophic level below it. The size of the populations then, are
continually adjusted by the species interactions with both its food
supply and its predators. 49
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Carrying capacity: the largest population of a species that an
environment can support. 4 main factors that determine the carrying
capacity: 1. materials and energy: energy, water, carbon, and other
essential nutrients 2. food chains: the population size is limited
by the size of the populations at lower trophic levels. (Prey
limited by their predators and their food supply). 3. competition:
each organism has the same need as any other. They compete for
resources such as food, water, mates, space. 4. density: depending
on their size, environment and way of life, different species have
different needs for space. 50
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Closer look at competition: Two types of competition: 1.
intraspecific: among members of the same species 2. interspecific:
between different species 51
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A closer look at population density: Two types of factors can
also limit population sizes. 1. density-dependent factors: these
are factors that increase as the population gets bigger and
eventually lead to a decrease in the population size by increasing
death rate and lowering birth rate. * overcrowding
*parasites/disease *aggression amongst members * neglect of
offspring 52
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2. density-independent factors: can limit a population
regardless of its original size. * forest fire * flood * volcano *
weather: El Nino 53
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Population Growth Since all organisms reproduce, populations
tend to grow over time If unlimited resources are present, growth
will be exponential It will proceed very quickly for rapidly
reproducing organisms and more slowly for slowly reproducing ones
The curve, however, will always be a J curve or an exponential
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Population Growth 2 Resources are never unlimited, though. As
population rises, resources decline. If the growth is too rapid,
resources are rapidly depleted and a population crash can occur
This pattern occurs often with many populations (including humans)
For example... Gypsy moth caterpillar 56
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Population Growth 3 More often what happens is that the
resources slowly decrease, the growth rate slowly increases, and
they meet. This point that they oscillate around is the carrying
capacity of the environment for that particular organism S - shaped
curve 58
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Human Growth Patterns What are the causes of the rapid growth
of human populations? What are some possible consequences of this
growth pattern? What will our future look like? (Remember the
Reindeer?) 59
