Life Science
Chapter 2
Lessons 1-3
Characteristics of Living Things:
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Reproduce
Grow and Develop
All living things are made of cells
Contains the same basic chemicals (carbon, hydrogen, oxygen)
Perform metabolic activities (digestion, respiration) requiring energy
Respond to their environment (stimulus triggers a response)
Spontaneous Generation:
This theory erroneously stated that living things could come from non-living things.
Francesco Redi disproved theory of Spontaneous Generation using jars of meat (1600’s).
Louis Pasteur later supported Redi’s work and proved that all living things must come from
other living things by experimenting with boiled and unboiled bacteria (1800’s).
Needs of Living Things:
Water
Food (energy)
Living Space (shelter/environment)
Homeostasis (stable internal conditions)
How do organisms get food?
Autotrophs:
Make their own food
Plants are autotrophs
AKA producers
Heterotrophs:
Unable to make their own food
Must obtain food from another organism
AKA consumers
What is homeostasis?
The ability of an organism to keep conditions inside its body stable
Temperature
Water levels
Classifying Organisms
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Classification is the process of grouping things based on their similarities
Taxonomy is the scientific study of how living things are classified
Binomial Nomenclature
 A two name system for naming living organisms
 Developed by Carolus Linnaeus in the 1750’s
 The first word in an organism’s name is its genus
 The second word in an organism’s names is its species
 These genus and species names are Latin because it was the language scientists used in
the 1700’s
Levels of Classification:
The more classification levels that two organisms share, the more characteristics they have in
common.
(Domain)
Kingdom
Phylum
Class
Order
Family
Genus
Species
(Greatest number of member/Share few characteristics)
(Very few members/Share many similar traits)
(Only one member)
Traits of living organisms:
 Unicellular (Microscopic organisms made of a single cell)
 Multicellular (Made of many cells)
 Autotroph (Organisms that produce their own food; aka producers)
 Heterotrophs (Organisms that cannot produce their own food; aka consumers)
 Eukaryotes (Genetic material is contained within a nucleus)
 Prokaryotes (Genetic material is not enclosed within a nucleus)
Three Domains of Life:
1. Bacteria
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2. Archae
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These organisms are prokaryotes
Prokaryotes are organisms whose cells lack a nucleus
These unicellular organisms may be autotrophs and/or heterotrophs
Microscopic organisms found in some of the most extreme
environments on Earth
Scientists think these harsh conditions are similar to those of ancient
Earth
These prokaryotes may be autotrophs and/or heterotrophs
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3. Eukaryotes
 Organisms whose cells contain nuclei (plural of nucleus)
Eukaryotes:
Protists
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May be autotrophs or Heterotrophs
Most are unicellular
A few are multicellular
Examples: euglena, ameba, slime molds
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Are all special heterotrophs known as decomposers
Most are multicellular (Ex: mushrooms, molds and mildew)
Yeasts are unicellular
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Multicellular
Autotrophs
Examples: mosses, ferns, sunflower, oak tree
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Multicellular
Heterotrophs
Examples: sponges, earthworms, dogs, humans
Fungi
Plants
Animals
Cell Theory:
History
1500’s
Microscope is invented
1600’s
Robert Hooke
Writes a book called “Micrographia”
Many sketches of small insects (fleas)
Viewed cork tissue and named “cells”
Anton von Leeuwenhoek
Read Hooke’s book
Developed better microscopes than contemporaries
Viewed tooth plaque, blood, rainwater,etc.
Referred to bacteria as “animalcules”
Matthias Schleiden
German botanist
Determined that plants are made of cells
Theodor Schwann
German physiologist
Determined that animals are made of cells
Rudolf Virchow
Determined that cells must come from other
existing cells
Cell Theory states:
All living things are made of cells.
Cells are the basic unit of structure and function.
Cells come from other existing cells.