Do now: Look at the flask of bacteria. Bacteria can double in number every 20 minutes. However, at some point, the doubling stops? Why do you think this happens?

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Do now Look at the flask of bacteria. Bacteria
can double in number every 20 minutes. However,
at some point, the doubling stops? Why do you
think this happens?
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Fruit flies
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What aim does this suggest?

• Why do the bacteria stop growing and doubling in
  number?

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What factors would limit the growth of bacteria?

• Population growth (describe a population)
• Closed system
• Example bacterial culture in a covered,
  stoppered flask
• What factors would be limited?
• Food supply
• Water supply
• Build up of waste

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Create a sketch of a graph of the bacterias
growth over time
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Now imagine if we are out in the wild

• The bacteria are not confined in a flask
• It could be any organism in an open environment,
  such as a deer in a forest
• What is this system called?
• What additional factors might limit their growth?

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Open system

• Example wild population of deer
• Limiting factors
• Food supply
• Water supply
• Temperature
• Predators
• Diseases
• Competition
• Destruction of their habitat

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Could you imagine that the population would
eventually reach a maximum?

• Why?
• Carrying capacity maximum population that a
  given environment can support
• Lets look at some other factors that might
  affect populations

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Predators and prey
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Think about the individuals in a population

• Who do you think would be most likely to be
  killed by predator? Why?
• The weakest and worst adapted
• How do you think this would benefit the
  population of prey overall?
• The fittest survive and are able to reproduce,
  giving the predators lots to eat (more food)

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What about human population in the world?

• Why are human populations increasing so much in
  the world today?
• Increases in farming and producing food
• This has changed the carrying capacity
• Improvements in sanitation-clean water
• Improvements in health care and medicine

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Predict what you think will happen to the world
population

• Why?
• Support your opinion

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Summary

• Explain the difference between an open and closed
  system
• What factors limit a population?
• Explain what is meant by carrying capacity

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Homework

• Stereomicroscope lab due tomorrow (Wednesday)
• Due Thursday Miller and Levine Read pages
  118-134. Do page 123, 1,2,3,6 and p127, 1,
  p132, 1,2,4

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2nd period of double period

• We will talk about the bottle biology lab
• How do we write it in general
• How do we write the different sections
• When is it due
• What to do if you need extra help
• I will return the exams