Characteristics of Life

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Characteristics of Life

• Chapter 1 Section 3

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Biology

• Again, Biology is the study of LIVING things

• What are living things?

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• Describing what is ALIVE is not easy
• Living things share the following characteristics

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Characteristics of Living Things

1. Made up of units called Cells
2. Reproduce
3. Based on universal genetic code
4. Grow and Develop
5. Use materials and energy
6. Respond to environment
7. Maintain a stable internal environment
8. Change over time

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1. Living things are made up of units called Cells

• A cell is a collection of living matter enclosed
  by a barrier that separates the cell from its
  surroundings.
• They are the smallest units of an organism that
  can be considered alive.
• They are complex and highly organized

http//www.udel.edu/Biology/Wags/wagart/anaglyphpa
ge/anaglyph.html
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Unicellular or Multicellular

• Unicellular cells consists of
  only a single cell.
• More commonly are multicellular
  organisms
• Multicellular organisms consist of many cells
  (hundreds, even thousands or more!)

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2. Living things Reproduce

• All organisms produce new organisms through a
  process called Reproduction.
• There are 2 kinds of reproduction
• Sexual two cells from different parents unite
  to produce the first cell of the new organism
• Asexual the new organism has a single parent.

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3. Living things are based on a Universal Genetic
Code

• We resemble our parents (usually)
• In asexual reproduction, offspring and their
  parents have the SAME traits
• With sexual reproduction, traits vary.
• Our genetic code depends on our DNA

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4. Living things Grow and Develop

• All living things grow at some point in their
  lives
• Bacteria even grow, even if it is just a simple
  increase in size.
• Multicellular organisms grow by developing.
• The many cells divide and become larger and
  take on different sizes and shapesthis
  is called differentiation

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5. Living things obtain and use Materials and
Energy

• What do we need as we grow and develop?
• Living things need a constant supply of materials
  to grow and develop.
• Metabolism a set of chemical reactions which an
  organism builds up or breaks down materials as it
  carries out life processes.
• Plants use photosynthesis for energy.
• Nature is a chain reaction of organisms relying
  on other organisms for energy.

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6. Living things respond to their Environment

• Environment our surroundings
• We respond to what is around us
• A stimulus is a signal to which an organism
  responds.
• Response an adjustment or a reaction
• For example, lets talk about what a plant does in
  its environment

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How does a plant react to environment?

• When there is water and the ground is warm enough
  a plant seed germinates.
• The roots respond to gravity and grow down into
  the soil.
• The leaves and stems grow toward light

http//www.phototour.minneapolis.mn.us/2181
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Adaptation

• As living things, we adapt to what is around us
• Adaptation Inherited characteristics that helps
  an organism survive
• Ex structure,
  behavior and
  processes
• Ex lizard

http//www.cs.umd.edu/mattkat/Snorkling/waterliza
rd.jpg
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7. Living things maintain a stable Internal
Environment

• External environment can be harsh
• Living things must stay fairly constant
  internally to survive.
• Homeostasis where organisms maintain a
  relatively stable internal environment.
• Thermometer we shiver...we sweat

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8. Living things change over time

• As a group, organisms evolve, or change over
  time.
• Over a few generations, the changes may not be
  significant, but over hundreds of generations
  they are.