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What is Life?. Think of an example of a living thing…. What is it? How do you know it is living?. Examine the items provided. Which one is living? Which is dead? Which is non-living? HOW CAN YOU TELL? What are the characteristics that allow you to make that conclusion? Class share.

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What is Life?

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Think of an example of a living thing
Think of an example of a living thing…

  • What is it?

  • How do you know it is living?


Examine the items provided
Examine the items provided

  • Which one is living?

  • Which is dead?

  • Which is non-living?

  • HOW CAN YOU TELL? What are the characteristics that allow you to make that conclusion?

  • Class share


Characteristics of living things
Characteristics of Living Things

  • Highly organized and contain many complex chemical substances

  • Composed of one or more cells

  • Use energy

  • Grow

  • Possess a definite form and limited size

  • Limited lifespan

  • Reproduce

  • Respond to changes in their environment

  • Groups of living things evolve over time


Make a table
Make a Table

Living

Non-Living


Place the following items
Place the following items

  • Toenail

  • Sun

  • Hair

  • Nerve cell

  • Leaf

  • Fire

  • Tree Bark

  • Water

  • Algae

  • Seaweed


Why is fire not considered living
Why is fire not considered living?

  • It needs oxygen

  • It produces carbon dioxide

  • It “consumes” fuel or “food”

  • It grows

  • It reproduces

  • Fire is a chemical reaction (combustion reaction)

    • fuel + O2 ashes + CO2



Something from nothing
Something from nothing??

  • Sometimes living things seem to appear out of “nowhere”!

  • Think of an example


What was happening

  • Observation 1: 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 there previously.

What was happening?


What was happening1

  • Conclusion: People thought that muddy soil gave rise to the frogs.

  • What do you think was really happening?

What was happening?


What was happening2

  • Observation 2: In many parts of Europe, medieval farmers stored grain in barns with thatched roofs. As a roof aged, it was not uncommon for it to start leaking. This could lead to spoiled or moldy grain, and then there were lots of mice around.

What was happening?


What was happening3

  • Conclusion: They thought the mice came from the moldy grain.

  • What do you think was really happening

What was happening?


Aristotle

Aristotle

Greek philosopher (384-322 BC)


Abiogenesis vs biogenesis

  • ABIOGENESIS between nonliving substances.: the theory that non-living things can be transformed into living things,

  • BIOGENESIS: living organisms come from other living organisms.

ABIOGENESIS vs BIOGENESIS


Van helmont

  • Over 300 between nonliving substances.years ago, a Belgian doctor, van Helmontset up an experiment to test abiogenesis

  • He concluded that mice could be created from grains of wheat and a dirty shirt!

van Helmont

1580 - 1644


What is wrong with this experiment
What is wrong with this experiment between nonliving substances.?


Development of the scientific method
Development of the Scientific Method… between nonliving substances.

  • Up to this point, science was based on observation and analysis

  • people began to see that this was inadequate and that controlled experiments were needed to test hypotheses


Francesco redi

  • In 1668, Italian physician, between nonliving substances.Redi, conducted an experiment to test abiogenesis

  • Showed that flies were not produced by rotting meat.

Francesco Redi

1626 - 1697


What is better about this experiment
What is better about this experiment between nonliving substances.?


Describe and draw redi s experiment
Describe between nonliving substances.and draw Redi’s experiment

  • Answer the following questions…

  • What was the experimental variable?

  • What was the controlled variable?

  • What was the “active ingredient” that people believed was needed for spontaneous generation?

  • What were his results?

  • What was Redi’s ultimate conclusion?


John needham
John Needham between nonliving substances.

1713 - 1781

In 1748, John Needham performed an experiment to study the spontaneous generation of microorganisms instead of maggots.

Micro-organisms grew in all flasks. He saw this as proof of spontaneous generation.


What is wrong with this experiment1
What is wrong with this experiment between nonliving substances.?


Lazzaro spallanzani
Lazzaro Spallanzani between nonliving substances.

1729 - 1799

In 1768, Spallanzani performed an experiment to disprove Needham

Micro-organisms did not grow in the sealed flask. He felt this “disproved” abiogenesis.


What is better with this experiment what is still wrong
What is better with this experiment between nonliving substances.? What is still wrong?


What is still wrong
What is still wrong? between nonliving substances.

  • Critics said that, by sealing his flasks, he had cut off access to a key ingredient for abiogenesis – fresh air. That was why no micro-organisms grew.

  • Spallanzani could not think of a way of letting air but not airborne micro-organisms into his flasks.

  • So the theory of abiogeneisis survived Spallanzani’s challenge and lived on

  • Spallanzani’s findings were used as a new way to preserve food – canning!


Louis pasteur
Louis Pasteur between nonliving substances.

1822 - 1895

In 1864, Louis Pasteur “definitively” disproves abiogenesis

The swan-necked flask developed by Pasteur enabled him to definitely disprove abiogenesis for micro-organisms by showing that these creatures arise in food from airborne spores.


What is better with this experiment
What is better with this experiment between nonliving substances.?


Summary questions
Summary Questions between nonliving substances.

  • 1. What are some problems that scientists have with observations?

  • 2. What is a hypothesis?

  • 3. Why did early scientists believe that frogs came from mud?

  • 4. Define abiogenesis and biogenesis, give your own example for each.


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