Assignment Due Friday
Living
Non-Living?
Organize the following into
your table..
Toenail
 Sun
 Hair
 Nerve Cell
 Leaf

Fire
 Tree bark
 Water
 Algae
 Bacteria

What makes
something alive?
Describe ways in which the “Baby”
looked “alive”
2. What characteristics of living things
are not shown by the “Baby”?
1.
10 Characteristics of Life
1.
Organization
6. Excretion
2.
Reproduction
7. Responsiveness
3.
Growth &
Development
8. Movement
4.
Nutrition
(feeding)
10. Evolution
5.
Respiration
9. Homeostasis
Organize the following into
your table..
Toenail
 Sun
 Hair
 Nerve Cell
 Leaf

Fire
 Tree bark
 Water
 Algae
 Bacteria

Origin of Life
17
18
Aristotle (384 –322 BC)
Proposed
the theory of
spontaneous generation
Also called abiogenesis
Idea that living things can
arise from nonliving matter
Idea lasted almost 2000
years
19
Spontaneous Generation
For centuries, people based their
beliefs on their interpretations of
what they saw going on in the world
around them without testing their
ideas
 They didn’t use the scientific
method to arrive at answers to
their questions
 Their conclusions were based on
untested observations

copyright cmassengale
20
Examples of
Spontaneous
Generation
21
Example #1
 Observation:
Every year in
the spring, the Nile River
flooded areas of Egypt along
the river, leaving behind
nutrient-rich
mud
that
enabled the people to grow
that year’s crop of food.
However, along with the
muddy soil, large numbers of
frogs appeared that weren’t
around in drier times
22
Example #1
Conclusion: It was perfectly
obvious to people back then
that muddy soil gave rise to
the frogs
23
Example #2
 Observation:
In many parts of
Europe, medieval farmers stored
grain in barns with thatched
roofs (like Shakespeare’s house).
As a roof aged, it was not
uncommon for it to start leaking.
This could lead to spoiled or
moldy grain, and of course there
were lots of mice around.
24
Example #2
Conclusion: It was obvious to
them that the mice came
from the moldy grain.
25
Example #3
Observation:
In the cities
centuries ago, there were no
sewers, no garbage trucks, no
electricity, and no refrigeration.
Sewage flowed down the streets,
and chamber pots and left over
food were thrown out into the
streets each morning. Many
cities
also
had
major
rat
problems and a disease called
Bubonic plague.
26
Example #3
Conclusion: Obviously, all
the sewage and garbage
turned into the rats
.
27
Up to this point, science was based on observation and
analysis…now, experiments were needed to test the
hypothesis.
https://www.youtube.com/watch?v=WNByRghR6sw
Disproving
Spontaneous
Generation
30
Francesco Redi
copyright cmassengale
31
Francesco Redi (1668)
 In
1668, Francesco Redi,
an Italian physician, did
an experiment with flies
and
wide-mouth
jars
containing meat
32
Redi’s Experiment
 Redi
used open & closed
flasks
which
contained
meat.
 His hypothesis was that
rotten meat does not turn
into flies.
 He observed these flasks
to see in which one(s)
maggots would develop.
33
Redi’s Findings
 He
found that if a flask was
closed with a lid so adult flies
could not get in, no maggots
developed on the rotting meat
within.
 In
a flask without a lid,
maggots soon were seen in the
meat because adult flies had laid
eggs and more adult flies soon
appeared.
34
Redi’s (1626-1697) Experiments
Evidence against spontaneous generation:
1. Unsealed – maggots on meat
2. Sealed – no maggots on meat
3. Gauze – few maggots on gauze, none on
meat
copyright cmassengale
35
Results of Redi’s
Experiments
 The
results of this experiment
disproved the idea of spontaneous
generation for larger organisms,
but
people
still
thought
microscopic organisms like algae or
bacteria could arise that way.
36
Disproving
Spontaneous
Generation of
Microbes
37
Anton van Leeuwenhoek (1674)
 Leeuwenhoek
began making and
looking through simple microscopes
 He often made a new microscope
for each specimen
 He examined water and visualized
tiny animals, fungi, algae, and
single celled protozoa; “animalcules”
 By end of 19th century, these
organisms were called microbes
38
Anton van Leeuwenhoek
1632-1723
copyright cmassengale
39
Leeuwenhoek’s
Microscope
40
John Needham (1745)
 Showed
that
microorganisms
flourished in various soups that
had been exposed to the air
 Claimed that there was a “life
force” present in the molecules
of all inorganic matter, including
air and the oxygen in it, that
could
cause
spontaneous
generation to occur
41
Needham’s Results
Needham’s
experiments
seemed to support the idea
of spontaneous generation
People didn’t realize bacteria
were already present in
Needham’s soups
Needham didn’t boil long
enough to kill the microbes
42
Needham’s Experiment
copyright cmassengale
43
Lazzaro Spallanzani’s (1765)
 Boiled
soups for almost an hour
and sealed containers by melting
the slender necks closed.
 The soups remained clear.
 Later, he broke the seals & the
soups became cloudy with
microbes.
44
Spallanzani’s Results
45
Conclusion
Critics
said sealed vials did
not allow enough air for
organisms to survive and that
prolonged heating destroyed
“life force”
Therefore, spontaneous
generation remained the
theory of the time
46
The Theory Finally
Changes
copyright cmassengale
47
How Do Microbes Arise?
 By
1860, the debate had become so
heated that the Paris Academy of
Sciences offered a prize for any
experiments that would help resolve
this conflict
 The
prize was claimed in 1864 by
Louis Pasteur, as he published the
results of an experiment he did to
disproved spontaneous generation in
48
microscopic organisms
Louis Pasteur (1822-1895)
copyright cmassengale
49
Pasteur's Experiment Step 1
S-shaped
Flask
Filled with broth
The special shaped was
intended to trap any
dust particles
containing bacteria
50
Pasteur's Experiment Step 2
Flasks boiled
 Microbes Killed

51
Pasteur's Experiment Step 3
 Flask
left at various
locations
 Did not turn cloudy
 Microbes not found
 Notice the dust that
collected in the neck of
the flask
52
And so, 2000 years after it started the
debate of abiogenesis vs. biogenesis is
settled:
Biogenesis: Life comes from life, not from
spontaneous generation of non-living
things!!!
https://www.youtube.com/watch?v=dYphAH2tKYE