Science TAKS Objective 3

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Science TAKS Objective 3

• The student will demonstrate an understanding of
  the interdependence of
• organisms and the environment.

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4 Main Concepts

• Organisms and the environment are dependent upon
  each other as seen in
• Ecology
• Evolution
• Plants
• Microbiology (bacteria and viruses)

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Food chains show the energy flow through an
ecosystem.

• On your paper draw a food chain.

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Does your food chain look like one of these?
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Food chains give you a lot of information

• What do the arrows in the food chain represent?
• The flow of energy
• What is the ultimate source of all the energy
  available on earth?
• The sun
• How can we label the levels of a food chain?
• See the next slide..

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Study the labels on the food chains and add these
vocabulary terms to your food chain.
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A food web is more realistic than a food chain.
Why?
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What would happen to the number of krill (prey)
if the number of Baleen whales (predator)
increased?
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• If the number of predators increases, the number
  of prey will decrease!

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Sometimes pyramids are used to illustrate the
numbers, biomass, and energy of each trophic
level (feeding level).
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Using the pyramid on the previous slide, answer
these questions on your own paper.

• Which trophic level has the most energy?
• Which trophic level has the most biomass (living
  mass)?
• Which trophic level has the smallest number of
  organisms?
• Do you remember how much energy is passed from
  one trophic level to the next?

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Answers

• The producers in the first trophic level have the
  most energy, and the energy decreases as trophic
  level increases.
• The producers also have the greatest biomass.
• The highest trophic level (the 3rd) has the least
  organisms. There are always fewest carnivores.
• Only 10 of the energy is passed from one trophic
  level to the next!

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SYMBIOSIS

• On your paper write an example of
• Mutualism (both organisms mutually benefit from
  the relationship)
• Commensalism (one organism benefits while the
  other is neither helped nor harmed)
• Parasitism (one organism benefits while the other
  is hurt)
• After one minute, have volunteers share and
  discuss their examples.

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Some more examples

• Mutualism E. Coli bacteria live in our colon
  (large intestine) receiving a nice place to live
  and helping us digest our food.
• Commensalism A squirrel lives in a tree and
  doesnt hurt or help the tree.
• Parasitism A tape worm lives in your stomach
  eating all your food and making you starve! Also
  ticks, fleas, leeches.

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A Little About Evolution

• Darwin developed the theory of natural selection,
  a.k.a survival of the fittest.
• The organisms with the genetic traits that helped
  them survive long enough to reproduce would pass
  on those favorable traits to their offspring.
• Over time, the whole population would have those
  favorable traits. (Populations, not individuals,
  change over time.)

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On your paper write some adaptations that would
help

• A rabbit survive in the snow?
• An insect survive in the rainforest?
• A bacteria survive against anitbiotics that
  attack its ribosomes? (hint ribosomes are the
  organelles that make proteins)

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Possible Answers

• A white rabbit would survive better in the snow
  than a black rabbit camoflague
• An insect that looks like a tree branch or like a
  poisonous insect would survive better in the
  rainforest mimicry
• A bacteria could become resistant to antibiotics
  if a mutation prevented the antibiotic from
  penetrating the cell membrane or if a mutation
  changed the ribosome enough so the antibiotic did
  not affect it.

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What evidence do we have for evolution through
natural selection?

• Fossil record
• Anatomical similarities homologous structures
• Embryological similarities (prenatal development)
• DNA sequences

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Homologous Structures
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DNA Sequences

• Recall that DNA sequence codes for amino
  acidsthe building blocks of proteins.
• The more similar a sequence of amino acids, the
  more similar the DNA.
• Look at the picture on the next slide and analyze
  which 2 organisms are the most related and the
  least related based upon the amino acids in their
  hemoglobin proteins. (Hemoglobin is the protein
  that carries oxygen in red blood cells.)

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Plants are organisms that interact with animals
and with the envirionment

• On your paper list some adaptations plants have
  to
• Prevent water loss
• Maximize sunlight
• Defend against predators
• Disperse their seeds

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Plants close the stomata on the underside of
their leaves to prevent water loss
The stomata would be on the top surface of the
leaf if it is a water lily!
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A cactus needles are modified leaves to prevent
water loss.
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Most plants have broad leaves to maximize
sunlight absorption
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Plant defenses against predators

• Poisonous leaves, berries
• Bitter or bad-tasting
• Thorns / Spines
• Can you think of any others?

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Plants are sneaky inseed dispersal!

• Wind carries dandelion seeds
• Animals eat berries and disperse the seeds later
  in their feces
• Cockleburs attach to animal fur

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All about bacteria

• Living, unicellular organisms
• Prokaryotes (no nucleus in the cell)
• Spread through hosts
• Harmful bacteria cause diseases including strep
  throat and diptheria
• Helpful bacteria
• live in our digestive tract (E. Coli)
• are nitrogen fixators living on the roots of
  plants and turn nitrogen gas into ammonia for the
  plant to use.
• Are used to make yogurt and ice cream
• Act as decomposersthe last step in a food chain
• Antibiotics kill both beneficial and harmful
  bactieria in your body so you might get a
  stomachache when you take them.

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All about viruses

• Nonliving! Need a cell to reproduce.
• Structure is a protein coat with DNA or RNA
  inside
• Attack a cell when its protein coat fits into a
  receptor protein on a cell membrane
• Viral reproduction kills the host cell
• Cause diseases like HIV (infects helper T cells
  of the immune system), colds, smallpox, flu, warts

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Compare Bacteria And Viruses on your own paper

• Bacteria
• - living cell
• - reproduce through binary fission (like
  mitosis)
• - many are helpful
• - harmful cause diseases
• - killed by antibiotics

• Viruses
• - nonliving not a cell
• - cant reproduce without a host cell
• - protein coat with nucleic acid (DNA or RNA
  inside)
• - reproduction kills the host cell
• - cause diseases