I can…explain the experiments that prove “Life comes from Life” Get out your homework to be...

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 ThingsSection 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• Organisms must be able to keep 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.