I. History The Characteristics of Life • A. Spontaneous Generation or Abiogenesis • 1. 1st proposed by Aristotle • 2. Believed that complex, living organisms are generated by decaying organic substances, • Ex. 1. that mice would spontaneously appear in stored grain • or • 2. maggots spontaneously appear in meat.
I. History The Characteristics of Life • Spontaneous Generation or Abiogenesis • 3. Was widely believed until the 19th century. • 4. Several scientists performed experiments that disproved spontaneous generation • Francisco Redi • Lazzaro Spallanzani • Louis Pasteur
Pasteur’s Experiment Louis Pasteur 1859
B. Biogenesis • 1. The process of life forms producing life forms of the same kind • Ex. a spider lays eggs, which hatch into spiders • 2. The term is also used for the assertion that life can only be passed on by living things I. The Characteristics of Life
How can you tell if something is alive? I. The Characteristics of Life
Interesting Fact: Biologists have devised a list of 5characteristics that define life. Interesting Fact: Something can be considered aliveONLYif it displays ALL 5 of the characteristics The Characteristics of Life
Anything that possesses all 5 of the characteristics of life is called an organism. The Characteristics of Life
II. The 5 Characteristics of Life A. Cellular Organization celltissueorgansystemorganism B. Growth & Development C. Reproduction D. Adaptation to Environment E. Maintenance of Homeostasis
A. Cellular Organization - “All living forms of life are made up of cells and become more organized from this basic unit of life” Ex. -Cells form tissues -Tissues form organs -Organs form organ systems I. The 5 Characteristics of Life
B. Growth & Development I. The 5 characteristics of life • Does it grow? • Growth – an increase in the # of cells • making up an organism increases it’s size • Does it develop? • Development – as cell #’s increase, they begin to diversify causing changes to take place throughout the the life span of the organism
C. Reproduction I. The 5 Characteristics of Life • All living organisms are able to reproduce themselves • Even one cell organisms replicate themselves
D. Adaptation to Environment I. The 5 Characteristics of Life • All living organisms are able to adapt to their surroundings. • “to adapt” -- to be able to react or respond • - to something in the environment • - to a “stimulus”
E. Maintain Homeostasis I. The 5 Characteristics of Life • All living organisms are able to maintain a relatively constant internal environment that is suitable for it’s life • Homeostasis - ? • “homo” + “static”
The Characteristics of Life • An Amazing Fact: THE HUMAN BODY • A collection of a trillion,diverse and highly organized cells • Whatever it takes to keep this collection of a trillion cells “alive” = what it takes for you and I to stay alive! WELCOME TO 21ST CENTURY H.S. BIOLOGY! A year of study to answer this question: What DOES IT TAKE to keep cells alive?