1 Science 7 ENVIRONMENTAL SCIENCE Populations and Communities Science 7 LIVING THINGS AND THE ENVIRONMENT • Ecosystem: – All the living and nonliving things that interact in a particular area – An organism obtains food, water, shelter, and other things it needs to live, grow and reproduce from its surroundings – Ecosystems may contain many different habitats Science 7 LIVING THINGS AND THE ENVIRONMENT • Habitat: – The place and organism lives and obtains all the things it needs to survive – Example: • Prairie Dog • Needs: – Food – Water – Shelter – Etc. Science 7 LIVING THINGS AND THEIR ENVIRONMENT • Biotic Factors: – The living parts of any ecosystem – Example: Prairie Dogs • Hawks • Ferrets • Badgers • Eagles • Grass • Plants Science 7 LIVING THINGS AND THEIR ENVIRONMENT • Abiotic Factors: – Water: • All living things require water for survival • Your body is 65% water • A watermelon is 95% water • Plants need water for photosynthesis for food and oxygen production Science 7 LIVING THINGS AND THEIR ENVIRONMENT • Abiotic Factors con’t – Sunlight: • Necessary for photosynthesis • Organisms which use the sun form the base of the food chain
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LIVING THINGS AND THELIVING THINGS AND THE ENVIRONMENT •Ecosystem: –All the living and nonliving things that interact in a particular area –An organism obtains food, water, shelter,
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Science 7
ENVIRONMENTAL SCIENCE
Populations and Communities
Science 7
LIVING THINGS AND THE
ENVIRONMENT
• Ecosystem:
– All the living and nonliving things that interact in a particular area
– An organism obtains food, water, shelter, and other things it needs to live, grow and reproduce from its surroundings
– Ecosystems may contain many different habitats
Science 7
LIVING THINGS AND THE
ENVIRONMENT
• Habitat:
– The place and organism
lives and obtains all the
things it needs to survive
– Example:
• Prairie Dog
• Needs:
– Food
– Water
– Shelter
– Etc.
Science 7
LIVING THINGS AND THEIR
ENVIRONMENT
• Biotic Factors:
– The living parts of any
ecosystem
– Example: Prairie Dogs
• Hawks
• Ferrets
• Badgers
• Eagles
• Grass
• Plants
Science 7
LIVING THINGS AND THEIR
ENVIRONMENT
• Abiotic Factors:
– Water:• All living things require water for survival
• Your body is 65% water
• A watermelon is 95% water
• Plants need water for photosynthesis for food and oxygen production
Science 7
LIVING THINGS AND THEIR
ENVIRONMENT
• Abiotic Factors con’t
– Sunlight:
• Necessary for
photosynthesis
• Organisms which
use the sun form
the base of the
food chain
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Science 7
LIVING THINGS AND THEIR
ENVIRONMENT
• Abiotic Factors Con’t
– Oxygen:
• Necessary for most
living things
• Used by animals
for cellular
respiration
Science 7
LIVING THINGS AND THEIR
ENVIRONMENT
• Abiotic Factors con’t
– Temperature:
• The temperature of
an area determines
the type of
organisms which
can live there
• Ex: Polar Bears do
not live in the
tropics
• Ex: piranha’s don’t
live in the arctic
Science 7
LIVING THINGS AND THEIR
ENVIRONMENT
• Abiotic Factors con’t
– Soil:
• Mixture of rock
fragments, humus
(nutrients),
minerals, air, and
water
• Soil type dictates
flora in an area
Science 7
LIVING THINGS AND THEIR
ENVIRONMENT
•Populations:
– All the members of one species in a particular area
– Ex: the number of students in this class
•Communities:
– All the different populations which live in an area
– Ex: all the animals in the Seneca Park Zoo
– Ex: all the animals in a forest
Science 7
DETERMINING POPULATION SIZE
•There are several methods of determining
population size
• 1. Direct Observation:
– Actually counting, one by one, all of the members of
a population
– Ex: counting all the elephants in a Kenyan valley
– Ex: counting all the Robins in your backyard
Science 7
DETERMINING POPULATION SIZE
•2. Indirect Observation
– If members of a population are either small or hard
to find, counting their tracks or signs of life can give
an estimate of population size
– Ex: counting mud swallow nests instead of the birds
– Ex: counting spittle bug nests rather than the bugs
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Science 7
DETERMINING POPULATION SIZE
•3. Sampling
– In most cases you cannot count every member of the
population
– Sampling allows a researcher to count the number of
organisms in a small area and multiply to find the
number of organisms in a large area
– If there are 25 deer in a 10 acre by 10 acre area, and
the forest is 100 times that size, there are
approximately 2500 deer in the whole forest
Science 7
DETERMINING POPULATION SIZE
•4. Mark and Recapture Studies
– Researchers capture, tag and release a group of
animals in the environment
– Later, they capture another group of organisms in
the same area.
– If about ½ those caught are marked, then the first
group represented about ½ the population for that
species.
Science 7
CHANGES IN POPULATION SIZE
•Populations change in size when new members enter the population or when members leave the population
• Birth Rate:
– The number of births in a population in a certain amount of time
•Death Rate:
– The number of deaths in a population in a certain amount of time
Science 7
DETERMINING POPULATION SIZE
• Immigration and Emigration:
– Immigration refers to the organisms which move into
the population
– Emigration refers to the organisms which move out
of the population
Science 7
POPULATION LIMITING FACTORS
•A limiting factor is an environmental factor
that prevents a population from increasing
• They determine the “carrying capacity”
of the environment
– Carrying Capacity:
• The largest population of a particular
organism that the environment can
support
Science 7
POPULATION LIMITING FACTORS
• Food:
– Organisms require food to
survive
– When food is scarce, it
becomes a limiting factor
– If the environment cannot
provide enough food for a
population, individuals
will be culled
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Science 7
POPULATION LIMITING FACTORS
• Space:
– Organisms require space to exist and reproduce
– If a bird doesn’t have room to nest, it will not reproduce, thus slowing population growth
– Plants need room to capture sunlight, if large trees block the sun, small plants will not thrive under them
Science 7
POPULATION LIMITING FACTORS
• Weather:
– Temperature and precipitation limit population growth
– Ex: cold weather kills off insects limiting the population
– Ex: frost or snow can ruin a citrus crop
– Ex: an early frost can kill off your garden and the limit vegetable population
Science 7
HOMEWORK
•Page 28
•Numbers 1-5
• Use COMPLETE SENTENCES !!!!!!!
Science 7
ADAPTING TO THE ENVIRONMENT
• Natural Selection:
– the way that changes which make organisms better suited to
their environments occur
• Adaptations:
– The behavior and physical characteristics of a species that
allows it to survive successfully in the environment
• Niche:
– An organism’s role or how it makes a living
– Type of food, how it gets its food, what critters use the
organism for food
Science 7
ORGANISM INTERACTIONS
•Competition:
– The struggle between organisms to survive in a
habitat with limited resources
– Limited amounts of food, water, and shelter cause
organisms to be in conflict with each other
Science 7
ORGANISM INTERACTIONS
•Predation:
– When one organism kills and eats another
• Predator:
– Organism doing the killing
• Prey:
– Organism being killed and eaten
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Science 7
EFFECT OF PREDATION ON A
POPULATION
•An increase in predation, decreases the
population size
• A decrease in predation, increases the
population size
– Ex: Moose and Wolves on Isle Royale, in Lake
Superior
• Moose pop. rose, Wolf pop. Rose
• Moose pop. fell due to predation, wolf
pop. fell due to lack of prey
Science 7
SYMBIOSIS
•A close relationship between two species
that benefits at least one of them.
Science 7
SYMBIOTIC RELATIONSHIPS
•Mutualism:
– A relationship where BOTH species benefit
– Ex:
• Honey Bees and Dandelions
– Honey bees use nectar for food, and dandelions get their
pollen spread from plant to plant
Science 7
SYMBIOTIC RELATIONSHIPS•Commensalisms:
– A relationship in which one species benefits and the
other is neither helped nor harmed
– Ex:
• Robins building their nest in a maple tree
– However: commensalism is rare in nature since one
or both of the organisms involved are either helped
or harmed a little
Science 7
SYMBIOTIC RELATIONSHIPS•Parasitism:
– One organism lives on or inside another; thus
harming it
– Parasite:
• The organism that benefits; lives on or in
another organism
– Host:
• The organism that is harmed; is fed on
by the parasite
• Usually not killed because then the
parasite loses its food source
Science 7
SYMBIOTIC RELATIONSHIPS
•Parasitism Example:
– Deer Tick
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Science 7
HOMEWORK
•Page 38
•Questions 1-5
•Complete Sentences!!!!!!!
Science 7
CHAPTER 1 TEST
•Populations
•Communities
• Biotic and Abiotic Factors
• Population Dynamics
• Limiting Factors
• Adaptations
• Interactions between Organisms
Science 7
ENVIRONMENTAL SCIENCE
Chapter 2
Ecosystems and Biomes
Science 7
ENERGY FLOW IN ECOSYSTEMS
•Producers:
– Organism that can make its own food
– These organisms are generally plants
– Means of energy production is primarily, but not
always photosynthesis
Science 7
ENERGY FLOW IN ECOSYSTEMS
• Consumers:
– Organisms which obtain energy by consuming other organisms
– Herbivores:• Consumers that eat plants
– Carnivores:• Consumers that eat only other animals
– Omnivores:• Consumers that eat both plants and animals
– Scavengers:• Carnivore that feeds on dead, decaying organisms
Science 7
ENERGY FLOW IN ECOSYSTEMS
• Decomposers:
– Organisms that break
down wastes and dead
organisms to return raw
materials to the
environment; RECYCLERS
• Fungi:
– Molds and mushrooms
• Bacteria:
– Single celled organisms
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Science 7
FOOD CHAINS AND WEBS
• Food Chains:
– A series of events
in which ONEorganism eats
another and
obtains energy
Science 7
FOOD CHAINS AND WEBS
• Food Webs:
– 2 or more overlapping food chains in an
ecosystem
– How 2 or more organisms
interact with their
environment in terms of
energy transfer
Science 7
ENERGY PYRAMIDS
• A diagram that shows the amount of energy that moves from one feeding level to another in a food web– Most energy is available at the producer level
– At each higher level of the pyramid, less energy is available than at the level below
– Only about 10% of energy from one level is transferred to the next level
Science 7
HOMEWORK
•Page 50
•Numbers 1-5
•Complete Sentences!!!!!
Science 7
CYCLES OF MATTER
• Water Cycle:
– A continuous process by which water moves from earth’s surface to the atmosphere and then back
– Evaporation:• Process where liquid water, gains heat, and becomes water vapor (gas)
– Condensation:• The process where water vapor loses heat, and becomes a liquid water droplets to form clouds
– Precipitation:• Any form of water which falls to earth from the atmosphere
Science 7
THE WATER CYCLE
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Science 7
THE CARBON/OXYGEN CYCLE
• These two cycles are linked– Produces use carbon from carbon dioxide to produce carbon-containing molecules and release oxygen
– Consumers eat carbon-containing compounds for energy and breath oxygen; releasing carbon dioxide as a byproduct; for use by producers
Science 7
THE NITROGEN CYCLE
•How Nitrogen moves through the
environment
– Plants “fix” or capture “free” Nitrogen from the air
– Consumers eat N-compounds in plants
– Animal Waste and plant remains decompose;
bacteria release “Free” nitrogen back to the air
– Bacteria in roots of plants “Fix” the “Free” Nitrogen
into the plant again
– The Cycle Continues
Science 7
THE NITROGEN CYCLE
Science 7
HOMEWORK
•Page 55
•Questions # 1-5
•Complete Sentences
Science 7
BIOGEOGRAPHY
•The study of where organisms live
– Continental Drift:
• The slow movement of continents across
the earth’s surface
• Huge impact on biogeography
• Organisms were isolated from one
another and thus began to evolve in
different ways
Science 7
ORGANISM DISPERSAL
• the movement of
organisms from
one place to
another
• Example:
– Milkweed seed
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Science 7
ORGANISM DISPERSAL
• Wind
– Plants and small
organisms need assistance
to move
– Wind spreads seeds,
spores of fungi, and tiny
spiders
Whirling Nut (Gyrocarpus)
Science 7
ORGANISM DISPERSAL
• Water:
– Water can transport
objects which float
– Ex: coconuts and leaves
– Insects and small animals
get a free ride to a new
home aboard floating
rafts
Science 7
ORGANISM DISPERSAL
• Other living things:
– organisms can be carried
from place to place by
animals which come into
contact with them
– Ex: ducks carry algae
from pond to pond
– Ex: birds carry seeds and
drop them in their waste
– Ex: dogs carry sticky seeds
from place to place in fur
Science 7
EXOTIC VS. NATIVE SPECIES
•Native Species:
– Species that naturally
evolved in an area
– Ex: Northern Pike in
Conesus Lake
• Exotic Species:
– Species carried into a new
location by people
– Ex: Zebra Mussels
Science 7
LIMITS TO SPECIES DISPERSAL
• Physical Barriers:
– Water, mountains, and
deserts can make it
difficult for organisms to
move from one area to
another
Mount
Everest
Pacific OceanScience 7
LIMITS TO SPECIES DISPERSAL
• Competition:
– When organisms enter a
new area, they must
compete for survival
resources
– To survive, they must find
a unique niche in which
to make a living
– If no niche is available,
the organism will die out
and dispersion will stop
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Science 7
LIMITS TO SPECIES DISPERSAL
• Climate:
– Variation in climate serves
as a barrier to dispersal
– Organisms adapted to
warm, moist climates,
cannot survive in dry, cold
climates and visa versa
– This is why different
species are found at
different elevations in the
mountains
Science 7
HOMEWORK
•Page 59
•Numbers 1-5
•Complete sentences
Science 7
EARTH’S BIOMES
•Biome:
– A group of ecosystems with similar climate and
organisms
– Classified mainly by climate conditions-temperature