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Science TAKS Objective 3


Microbiology (bacteria and viruses) Food chains show the energy flow ... Embryological similarities (prenatal development) DNA sequences. Homologous Structures ... – PowerPoint PPT presentation

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Title: Science TAKS Objective 3

Science TAKS Objective 3
  • The student will demonstrate an understanding of
    the interdependence of
  • organisms and the environment.

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

Food chains show the energy flow through an
  • On your paper draw a food chain.

Does your food chain look like one of these?
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…..

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

Sometimes pyramids are used to illustrate the
numbers, biomass, and energy of each trophic
level (feeding level).
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
  • Which trophic level has the smallest number of
  • Do you remember how much energy is passed from
    one trophic level to the next?

  • 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!

  • 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.

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….

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.)

On your paper write some adaptations that would
  • 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)

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.

What evidence do we have for evolution through
natural selection?
  • Fossil record
  • Anatomical similarities homologous structures
  • Embryological similarities (prenatal development)
  • DNA sequences

Homologous Structures
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
  • Prevent water loss
  • Maximize sunlight
  • Defend against predators
  • Disperse their seeds

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!
A cactus needles are modified leaves to prevent
water loss.
Most plants have broad leaves to maximize
sunlight absorption
Plant defenses against predators
  • Poisonous leaves, berries
  • Bitter or bad-tasting
  • Thorns / Spines
  • Can you think of any others?

Plants are sneaky in seed 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 decomposers…the 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.

All about viruses
  • Nonliving! Need a cell to reproduce.
  • Structure is a protein coat with DNA or RNA
  • 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

Compare Bacteria And Viruses on your own paper
  • Bacteria
  • - living cell
  • - reproduce through binary fission (like
  • - 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
  • - reproduction kills the host cell
  • - cause diseases