Characteristics of Life

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Characteristics of Life

• Biology I Honors

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What does it mean to be alive?

• Not as obvious as it seems
• Sometimes the line between life and non-life is
  very blurry
• Example viruses
• Still, it is generally agreed that all living
  things share certain processes or characteristics
  in common

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Living things are ORGANIZED

• Levels of biological organization go from simple
  to complex
• Biosphere
• Ecosystem
• Community
• Species
• Population
• Organism
• Organ system
• Organ
• Tissue
• Cell
• Organelle
• Molecule
• Atom

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Biosphere

• All regions of Earth that contain life

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Ecosystem

• A region of the biosphere and all the living and
  non living things it contains

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Community

• All the different species of living things in an
  ecosystem
• Example Community around Monacan High School
• Robins
• Squirrels
• Grasshoppers
• Oak trees
• Pine trees
• Grasses
• People
• Etc.

7
Species

• Organisms that can interbreed with each other and
  create fertile offspring
• Example All humans belong to one species Homo
  sapiens

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Population

• A group of one species living in a particular
  area / community
• Example all of the Homo sapiens living in the
  area around Monacan High School

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Organism

• One individual living thing
• May be an animal, a plant or an amoeba

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Organ System

• A group of organs working together to do a common
  job

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Organ

• A group of different tissues working together to
  do a common job

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Tissue

• A group of similar cells working together to do a
  common job

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Cell

• The fundamental unit of life

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Organelle

• A cell part like a nucleus or mitochondrion

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Molecule

• Two or more atoms chemically combined

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Atom

• Smallest piece of an element that can exist

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Living things harvest and use energy

• Terms to know
• Heterotroph
• Autotroph
• Cellular respiration
• Photosynthesis

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Heterotroph

• Eat stuff

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Autotroph

• Make your own food

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Cell Respiration

• Breaking down food to get usable energy

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Photosynthesis

• Using sunlight to make food

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Universal Genetic Code

• Living things are based on a universal genetic
  code
• DNA

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Living things are made up of one or more cells

• Unicellular
• Multicellular
• Cells are
• Fundamental unit of life

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Maintain a stable internal environment

• Homeostasis

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Living things evolve

• Change in the kinds of species on Earth over time

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Living things grow and develop

• Grow in size
• Develop change in body form

27
Living things respond to their environment

• Example Animals generally run away if you try
  to hit them (or point a ray gun at them)
• Even plants respond to stimulus
• Growth towards light

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Living things reproduce

• Make offspring
• Sexual
• Asexual