Transcript Ch. 21 Notes

Ch. 21 Populations and
Communities
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Ch. 21.1 Living Things and the
Environment
Listen while Ms. Helm reads the story: p. 704
Vocabulary
• Organism- a living thing
– Obtains food, water, shelter, and other things it
needs to live, grow and reproduce from its
environment.
• Habitat – An environment that provides the
things the organism needs to live, grow and
reproduce.
Habitats have 2 parts:
Biotic (living, or once living)
• Grass
• Seeds
• Berries
• Hawks
• Ferrets
• Badgers
• Eagles
• Fur
• feathers
Abiotic (not living)
• 5 major categories:
• 1. Water
• 2. Sunlight
• 3. Oxygen
• 4. Temperature
• 5. Soil
Levels of Organization
»FOLDABLE:
• Organism (smallest – 1 living thing)
• Species (many of the same organism)
• Population (All the members of the same
species in an area)
• Community (all the populations in an area)
• Ecosystem (all the communities in an area)
Ch. 21.2 Studying Populations
Determining Population Size
• In order to study something, you need to
know how big the population is, and how it
changes over time.
• Some methods of determining the size of a
population are direct and indirect
observations, samplings, and mark-andrecapture studies.
Different Ways to Count a Population
• Direct Observation: The most obvious.
You count ALL the members.
• Indirect Observation: Sometimes, the
organism you are trying to study is hard to
see/find. Then you have to look for SIGNS of
your organism.
– Counting nests of birds, holes of prairie dogs, etc.
Ms. Helm’s Favorites:
• Sampling: When it’s too hard to count each and
every one:
– MAKE AN ESTIMATE!
– Count all the ones you can find in a small area, them
multiply to find the larger area. (exp: I have 10 acres. I
count all the trees on 1 acre, then multiply by 10)
• Mark-and-Recapture:
– Catch, and mark, all the ones you can find (animals).
Then come back in 2 weeks and try to catch as many
as you can. See how many you caught before and
compare that to the number that are new.
Mark-and-Recapture Equation
• Total Population = Number marked x total number captured
Number recaptured (with marks)
• Try:
• Pg. 719: Counting Turtles
HOMEWORK: Foldable:
• 4 methods of Determining Population Size
Fold
corners in
Changes in Population Size
• Populations can change in size for a few
reasons:
– Births(+) and Deaths(-)
– Immigration(+)/Emigration(-)
– (Im = in) / (Em = exit)
Obviously…
• Growing =
• BIRTHS(+) > deaths(-)
• IMMIGRATION(+) > emigration(-)
• Decreasing =
• Deaths(-) > BIRTHS(+)
• Emigration(-) > IMMIGRATION(+)
Population Density
• Its important to know HOW MANY there are,
but ALSO: how many IN AN AREA (are the
spread out or crowded?)
• Sorry, here’s some math for you:
• Population density = Number of individuals
Unit Area
– You should be able to use this equation on the
test/quiz (no calculator).
Limiting Factor
• Remember: Factor… (biotic factor, abiotic factor…
Factor = thing)
• Limiting Factor – an environmental factor that
causes a population to DECREASE! (not enough
food, water, space, weather, etc.)
• Its like making a cake, you might have 10 boxes of
mix, but only 3 eggs. You can only make 1 cake.
The EGGS are the LIMITING FACTOR! (you should
be able to figure out something like this on your
test!)
Space as a Limiting Factor
• Puzzle Lab?
Ch. 21.3 Interactions
Among Living Things
Video Field Trip!
Hide your Critter
• Ms. Helm will give you a piece of white paper
in the shape of a critter. Your job is to color it
so that it will blend in PERFECTLY in a secret
place in the classroom. You will tape it to the
surface of something in the room.
– YOU CANNOT HIDE IT UNDER/BEHIND something!
– Good Luck!
Adapting to the Environment
• Natural Selection (remember!) – when the
environment (mother nature) selects who
lives and dies. If its cold, you need lots of fur,
etc.
• Adaptations – behaviours or physical
characteristics to help you survive:
– Behaviour: hide when the wolf is chasing you
– Physical: have thick fur in the snow
Niche
• Niche – (nitch) an N dimensional
hypervolume.
• WHAT!?!?!?!?!?!?!?!!?
• Basically, that special place where everything
fits in just right. Every organism has a variety
of adaptations that are suited to its specific
living conditions.
– What makes a scorpion perfect for the desert? It
perfects fits that Niche!
Interactions
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•
•
3 types:
Competition
Predation
Symbiosis
Competition
• Fighting for stuff, duh!
– But not always physically…
• It could be racing for food (remember the bird beak
lab?)
• It coold be trying to look sexy for the lady frog, etc.
Predation
• Hunting and getting eaten.
• Bird eats Frog:
– Bird = predator
– Eating = predation
– Frog = prey
• Too much Predation = SMALLER POPULATION
– Pg. 725 Math analyzing Data
Predator Adaptations
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•
•
Cheetahs run fast
Jellyfish tentacles are poisonous
Some plants have sticky bulbs to catch insects
Big eyes on owls to see at night
Sonar for bats
Prey Adaptations
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•
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Being very alert (think sketchy deer)
Skunk spray (I’ll give you a stick eye!)
Camouflage ( you can’t see me!)
Mimicry (look like something scary!)
Warning Coloring (Look OBNOXIOUS!)
Alert
Skunk Spray
Camouflage
Mimicry
Warning Colors
Symbiosis
• Can’t we all just get along!
• 3 Kinds:
– Mutualism (you win, I win, we ALL WIN!)
– Commensalisms (I win, you come out even)
– Parasitism (I win, you lose)
Ch. 21. 4 Changes in Communities
• Read story from Ecology Book
• Coloring Activity
QUIZZES AND TESTS!
• KNOW HOW TO USE YOUR EQUATIONS! (I will
give them to you, you need to plug things in)
• Know Your VOCABULARY!
• Interpret Graphs!
• Pick out Limiting Factors!
• Study Guide: pg. 735 from text book. Answers
on next few slides: quiz your self before. I will
not go over them with you.
Ch. 21 Study Guide Answers
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Organizing Information:
1. direct observation
2. indirect observation
3. sampling
4. mark-and-recapture studies
Reviewing Key Terms
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•
•
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1. B, 2. C, 3. B, 4. C,
6. true
7. false; population
8. true
9. false; competition
10. false; host
5. D
• 11. Sample answer: biotic – trees, birds; abiotic –
sunlight, soil
• 12. Plants and algae use the energy of sunlight to
combine water and carbon dioxide to make their
won food during photosynthesis. All consumers in
that ecosystem feed directly o r indirectly on
plants or algae.
• 13. Ecologist count the number of organisms in a
small area, and then multiply by the number of
units in the entire area to estimate the entire
population.
• 14. Limited space may make it impossible for
all members of the population to find places
to breed or make nests
• 15. Any two: Camouflage – The organism
blend in with its surroundings, making it
difficult for predators to see. Protective
covering – the organisms spines, shell or other
outer covering makes it painful or difficult for
predators to eat.
• 15. (continued) Warning coloring – an
organism that is poisonous has bright colors to
warn predators not to eat it.
• Mimicry- a harmless organism looks like
another organism that predators have learned
not to eat.
• False coloring – false “eyes” or other
structures can food predators and scare them
away.
• 16. Studying the entire population of the
species usually is not possible because the
population is too large or spread out.
• 17. Answers may include indirect observation
(counting egg clusters), sampling (counting
the number in a small area and then
multiplying by the number of units in the
entire area), or mark and recapture.
• 18. Organisms within a species share the same
niche. Because individuals within a species are
more similar, they will share many of the same
advantages and disadvantages in surviving in a
certain environment, which intensifies
competition for the limited resources.
Members of two different species may share
some parts of a habitat but do not usually
compete for all resources in the same way.
• 19. Primary succession; there is no soil (just
rocks) present and only pioneer organisms are
shown.
• 20. If birth rate > death rate, population size
INCREASES. If death rate > birth rate,
population side decreases. If immigration >
emigration, population size increases. If
immigration < emigration, population size
decreases.
• 21. ask Mrs. Simpson. If you can’t graph points on
a line, you haven’t been paying attention in math.
• 22. Highest: year 15; lowest: year 30
• 23. Possible answer: Beginning with 15,000 deer
at the beginning of the study, the population
increased steadily through year 15. From year 15
through the end of the study, the deer population
declines steadily, reaching the population’s
lowest point, 10,000 deer, in Year 30.
• 24. The severe winter may have killed the
weak or injured deer. Food shortage during
this winter also may have weakened deer or
caused them to starve.
• Standardized Test Prep pg. 737
• 1. C 2. H 3. A 4. F 5. B