Classification Intro Notes

Classification—the organization of living things into categories based on similar traits

   **millions of organisms have been identified, far too many to study all of them

    • need a way to categorize/organize them in order to study them

(rather than study all, can just study a group and understand things about all members of that group)

 

2 Purposes of classification systems:

  • Organisms are divided into groups according to characteristics
  • Organisms are given scientific names that identify what they are and show relationships with similar living things

Example: Homo sapiens = Human (identifies species)

            Homo erectus => shares “Homo” with humans, so must be related/similar to humans

 

Taxonomy—study of how things are related and classified

            Taxonomists: classify/name organisms based on characteristics

 

**First step in any classification system: Make observations

 

Observation—any information that is gathered with the five senses

            --anything seen, heard, felt, tasted, smelled

            --can be enhanced with tools (microscopes, rulers, balances, etc)

 

Classifying Living vs Nonliving Things

**All living things (on Earth) have similarities because all evolved from the same common ancestor billions of years ago**

Living things must have certain characteristics:

  • Cells—all organisms are made of 1 or more cells
  • DNA—all living things have DNA
  • Metabolism—organisms need to get and use energy, and get rid of wastes
  • Response—respond and adapt to environment
  • Growth/Development—all organisms grow and develop
  • Reproduce—organisms make more of the same species

**Must have all of these to be considered living**

 

  • Cells
    1. living things may be unicellular or multicellular
    2. all cells share some structures that have similar functions
    3. all cells must get energy from food, grow and reproduce, and respond to the environment

  • DNA
    1. All organisms have DNA, the code of life
    2. Gives each species its characteristics
    3. Provides differences in individuals of a species

  • Metabolism—all chemical reactions involved in maintaining the living state of cells in an organism
    1. Living things must get energy and use energy
      • Animals: get energy from food; breathe to help break down food into energy

    • Respiration: use oxygen to burn glucose (sugar) to get energy

                              C6H12O6 + 6O2 = energy + 6H2O + 6CO2

    • Plants: use sunlight to make food, which can be burned for energy
      • Photosynthesis: creation of glucose to give plants energy 
      • Still use RESPIRATION to use the energy

                     6H2O + 6CO2 + sunlight = C6H12O6 + 6O2

 

 

    • Fungus: uses decomposition to break down dead organisms to get energy

**Nearly all energy comes from the sun**

  • Respond to the Environment
    1. all living things react to important things in their environment
    2. respond to changes in light, heat, sound, chemical/mechanical contact
    3. cells help return bodies back to normal; keep a stable internal environment
    • Homeostasis—maintaining a balance inside the body or cells of organisms; example: maintaining body temperature

 

  • Living things grow/develop
    • All living things begin as 1 cell; multicellular organisms can add many more
    • Development—change or reorganization of body structures (not just a change in size)
      • examples: puberty, metamorphoses

  • Living things reproduce
    • asexual or sexual reproduction; create a new generation of organisms
    • without reproduction, species will go extinct

 

Living things: have all these characteristics

Non-living things: do NOT have all these characteristics

Once-living things (“dead”)—has characteristics of life, but no longer carries out functions of life