Exploring

1
Exploring Classifying Life

• Chapter 1

2
What is Life?

• All living things are called organisms
• Organisms must meet certain requirements
• All living things are organized
• Organisms are organized by cells
• A cell is the smallest unit of an organism that
  carries on the functions of life.
• Each cell has an orderly structure and contains
  hereditary material (DNA)

3
What is Life?

• All living things respond to their environment
• This means they can respond to a stimulus
• A stimulus is anything that causes some change in
  an organism
• I.e., heat, pain, sunlight
• A response is the way an organism reacts to a
  stimulus
• I.e., sweat, move away, grow towards light
• Homeostasis is the maintaining of
  proper conditions inside an
  organism
• Keep temperature, ph, mineral
  levels, etc. relatively constant

4
What is Life?

• Living things take in and use energy
• Three different ways
• Producers perform photosynthesis and get energy
  from the sun
• Some producers perform chemosynthesis and get
  energy from chemical sources
• Consumers perform respiration and get energy from
  their food

5
What is Life?

• Living things grow and develop
• Growth of multicellular organisms is due to an
  increase in the number of cells
• Growth of unicellular organisms is due to an
  increase in the size of the cell
• Development involves any changes that take place
  during the life of an organism

6
What is Life?

• Living things reproduce
• Reproduction can be either sexual or asexual
• Sexual reproduction is when two reproductive
  cells unite
• Ex pollen and egg
• Asexual reproduction is when one organism either
  splits or makes a copy of itself
• Ex bacteria and binary fission

7
What Do Living Things Need?

• Living things need a place to live that provides
  for all of the organisms needs
• Called a habitat
• Living things need raw materials, like water,
  proteins, fats, and sugars
• Used for food, energy, building blocks for new
  material

8
Review Questions

• What is the main source of energy used by most
  organisms?
• List 5 traits most organisms have.
• Why would you expect to see cells if you looked
  at a section of a mushroom cap under a
  microscope?
• In order to survive, what things do most
  organisms need?
• Why is homeostasis important to organisms?
• What are the similarities and differences between
  a goldfish and the flame of a burning candle?
• Which characteristic of life is essential for a
  species, but not for an individual organism?

9
Spontaneous Generation

• The early theory that living things could come
  from nonliving things
• If you left out food, maggots, flies, etc. would
  appear - no knowledge of little things.
• Was replaced by the theory of biogenesis
• Living things can only come
  from other living things
• Why was this replaced
  you say?
• Im glad you asked!

10
A Little History

• Francesco Redi (1668)
• Put decaying meat in some jars, then covered half
  of them. When fly maggots only appeared on
  uncovered meat, concluded they came from fly
  eggs, not from the meat.
• John Needham (1745)
• Heated broth in sealed flasks.
  Broth became cloudy with
  microorganisms - concluded that they came from
  spontaneous generation

11
A Little More History

• Lazzaro Spallanzi (1768)
• Broiled broth in sealed containers for
  longr than Needham. Only containers
  that were opened became cloudy.
• Louis Pasteur (1859)
• Disproved spontaneous generation by boiling
  broth in S-necked flasks that were open to the
  air. The broth became cloudy only when a flask
  was tilted and the broth was exposed to dusk in
  the S-neck. Glencoe, p.22

12
Alexander I. Oparin (1924)

• Hypothesizes that gases in Earths early
  atmosphere combined to form more complex
  compounds found in living things
• With help from the Sun, lightning, and geothermal
  energy, they combined
• The original gases were
• Ammonia
• Hydrogen
• Methane
• Water vapor
• New compounds washed into ocean and formed
  primordial soup.

13
Stanley L. Miller andHarold Urey

• Tested Oparins hypothesis
• Showed that chemicals found in living things can
  be produced artificially
• They sent an electric current through a mixture
  of gasses (ones mentioned previously)
• When they cooled, they condensed into the
  hypothesized primordial soup.
• Contained amino acids

14
Review Questions

• Whats the difference between spontaneous
  generation and biogenesis?
• Describe 3 experiments that helped disprove
  spontaneous generation.
• What were the results of the Miller-Urey
  experiment?
• Why was Oparins hypothesis about the origins of
  life important to Miller and urey?
• It was thought that in Spallanzi experiment, some
  vital force in the broth was destroyed. Was it?
  Explain.
• Hypothesize why Needham probably concluded that
  spontaneous generation occurred.

15
Aristotle

• Greek philosopher
• First to classify organisms
• Two groups
• Plants and Animals
• These groups were split up further
• Ex Animal group was split into four legs, fewer
  legs, blood, no blood, etc.

16
Carolus Linnaeus

• Introduced a system based on similar structures
  of organisms
• Came up with the most commonly used
  classification system
• Kingdom (humans - Animalae)
• Animalae, Plantae, Fungi, Protista, Monera
• Phylum (humans - Chordata)
• Class (humans - Mammalia)
• Order (humans - Primata)
• Family - (humans - Homonidae)
• Genus (humans - Homo)
• Species (humans - sapiens)
• Organisms in the same species can mate and
  produce fertile offspring

17
Modern Classification

• Modern systems are based on phylogeny
• Phylogeny is the evolutionary history of an
  organism
• The same divisions are used (Kingdom, Phylum,
  etc.), some animals are just put into different
  places
• Now there are 6 (some would say 8) kingdoms
• Animal, Plant, Fungus, Protist, Eubacteria,
  Archaebacteria
• Some split protist into animal-like protists,
  plant-like progists, and fungus-like protists

18
Binomial Nomenclature

• Two-word system used by Linnaeus to name species
• Homo sapiens
• The first word identifies the genus, or group of
  similar species
• Always capitalized, italicized when typed,
  underlined when written
• Homo
• The second word identifies the species
• Always lower-case, italicized when typed,
  underlinen when written
• sapiens

19
Why Use Scientific Names?

• Avoid mistakes - common names can be misleading
• Its also a universal language
• Show that organisms in the same genus are related
• Ex
• To give descriptive information
• The names mean something (in some language)
• To allow information to be organized easily

20
Tools for Classification

• Field Guides - descriptions and illustrations of
  organisms
• Dichotomous keys - detailed lists of identifying
  characteristics that include scientific names
• Example in Book (some mice of North America)

21
Review Questions

• What is the purpose of classification?
• What were the contributions of Aristotle and
  Carolus Linnaeus to classification of living
  things?
• How can you identify a species using a
  dichotomous key?
• Would you expect a field guide to have common
  names as well as scientific names? Why?
• Why can common names cause confusion?
• Think of a quick dichotomous key to help identify
  the people next to you.