What are the requirements of life?

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What are the requirements of life?
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What are the requirements of life?
Physical conditions which can sustain life
Water

• Nutrient and
• energy source

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What Is Life?
I. Introduction A. How do we tell what life is?
1. Dictionary a. the quality that
distinguishes a vital functioning being from a
dead body b. but what is that quality
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2. Intuitive knowledge a. living things
have complexity and ordered interaction among
those complex parts b. much more
difficult to describe or define life c.
develop criteria for identifying life
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B. Characteristics of life 1. Orderly
structure or organization a. complex
structure b. organic (carbon-based)
molecules
A
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2. Acquire and use materials/energy a.
maintain complexity b. maintain organization
c. require energy - directly i.
photosynthesis - indirectly i. energy
stored in materials
C
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3. Maintain Internal Environment - Homeostasis
a. organisms keep conditions in their bodies
fairly constant to live b. metabolism in
organisms is almost always constant c.
conditions include temperature, water levels,
salt levels
A
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4. Change during Lifetime a. development
occurs during organisms lifetime - organized,
replicated pattern of changes b. Growth -
at sometime in lifecycle, all organisms become
larger - conversion of acquired materials for
increased size
D
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5. Reproduction a. Living things reproduce
themselves b. Transmittal of genetic
material (e.g. DNA) to new generation
C
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6. Respond to stimuli Adjust to surroundings
a. react to physical or chemical changes in
their environment b. short term response
- within single lifetime 7. Populations are
modified adapt to environment a. long-term
response - requires multiple generations
(usually many generations) b. requires
modification due to genetic mutations c.
Adaptation
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Criteria for life
Does it 1) have orderly structure? 2) consume
energy? 3) maintain internal environment? 4)
develop or grow? 5) reproduce passing on
heritable traits? 6) respond to stimuli 7) as a
population, evolve to better fit the
environment? IS IT ALIVE?