I can…explain the experiments that prove “Life comes from Life” Warm Up:
I can…explain the experiments that prove “Life comes from Life”
Get out your homework to be checked.
Write down tonight’s homework.
Warm Up:
What are the 6 characteristics of life?
Life Comes from life
• Living things arise from living things through reproduction
• ….But, four hundred years ago people believed that life could appear from nonliving things…
CRAZY!?!?!
• They called this… SPONTANEOUS GENERATION
***the mistake idea that living things can arise from nonliving sources http://www.youtube.com/watch?v=WNByRghR6sw
Redi’s Experiment
• Francesco Redi – Italian doctor (1600’s)
• He designed a CONTROLLED EXPERIMENT to show flies do not arise from decaying meat
• Who remembers what a controlled experiment is???
• A scientist carries out 2 tests that are identical in every respect except for one factor
Redi’s Experiment
• Left jar = UNCOVERED
• Right jar = COVERED
• Manipulated
Variable?
• Whether or not the jar
Was covered
Pasteur’s experiment
• Louis Pasteur--- French chemist (mid-1800s)
• Some people still did not believe Redi… so Pasteur came up with a new experiment
• His experiment… demonstrated that new bacteria appeared in broth only when they were produced by existing bacteria
• Both experiments convinced people that LIVING
THINGS DO NOT ARISE FROM NONLIVING
MATERIAL
Pasteur’s experiment
Chapter 2: Living
Things
Section 1, Part 2
The needs of living things
• All living things need -----
• Water
• Food
• Living space
• Stable internal conditions
water
• All living things NEED WATER TO SURVIVE.
• WHY? Organisms need water to…
• Obtain chemicals from their surroundings
• Break down food
• Move substances within their bodies
• Reproduce
Food
• Organisms use FOOD AS THEIR ENERGY SOURCE.
• Plants: Capture the sun’s energy and use it for food
• Organisms that make their own food are called
AUTOTROPHS
• Examples: grass, moss, algae, trees, flowers…
• Organisms that CANNOT make their own food are called HETEROTROPHS
• Examples: animals, mushrooms, and slime molds…
Living space
• All organisms need a place to live
• Its surroundings MUST PROVIDE WHAT IT NEEDS
TO SURVIVE
• How do trees compete for space?
• Top of the trees for SUNLIGHT
• Below the ground for WATER AND
NUTRIENTS
• Come up with an example on your own!
•
Stable internal conditions
inside their bodies STABLE, EVEN WHEN
CONDITIONS IN THEIR SURROUNDINGS
CHANGE SIGNIFICANTLY.
• This is called….. HOMEOSTASIS
• Example: Your body temperature stays steady even when there are changes in air temperature.
