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Print Origins of life,
Scientific Method
What it means to be living

Mr. Talon

Origins of Life according to Science

“Where does life come from?”


Vocab: spontaneous generation
biogenesis

Where does life come from?

Old thoughts- Spontaneous generation- Living things come from non-living things.
-This idea was a theory for hundreds of years before scientists developed controlled experiments.

“Before the seventeenth century, some people thought that insects and fish came from mud, that earthworms fell from the sky when it rained, and that mice came from grain.” (text)

Newer thoughts and experiments-

Louis Pasteur, a French chemist disproved spontaneous generation.
Replaced with biogenesis- The theory that says Living things come only from other living things.

Pasteur used a swan necked flask (pg 22) - Only when the broth in the flask was exposed to the air did he find growth inside. Otherwise there was no growth.

Life’s Origins- Since life only can come from other life how did Earth’s life start?
The earth is 4.55 billion years old.
The oldest fossils are more than 3.5 billion years old.

This was determined independently by many scientists on different parts of the globe. Two radioactive isotopes of lead helped determine the age.
We can test the “Half-life” of the isotope. The time it takes for half of the radioactive lead to disappear.

By testing those calculations we can determine the age of anything.

Oparian- Russian scientist 1924-

Suggested that Earth’s early atmosphere had no oxygen and was made up of gases ammonia, hydrogen, methane, and water vapor.
He suggested that these gases could have combined to form the complex compounds found in living things.

Scientists still don’t know how the first cells formed on this planet but we have created the conditions of early earth and used electricity to make amino acids, cell walls, and other complex structures.

Scientific Method

Review: What is science?

Advice: Always ask questions, never stop questioning. You don’t have to live your life taking everything at face value. Be a free thinker. It will make you more powerful.

Types of Science- Many types according to what is being studied

Science involves Critical thinking- We solve problems every day using the scientific method. Let’s examine a CD player that isn’t working.

What would you do? -Check batteries, check cord (wall and unit), is there a CD in the player?
- You use your prior knowledge to determine the problem, you make an inference.

Scientific Method- (using the CD example)
1) State the problem- The CD player won’t work
2) Gather information- Does it need batteries? Is the CD missing? Is it plugged in?
3) Form a hypothesis- “If I plug in the CD player it will work.”
4) Test the hypothesis, Experiment- Plug it in.
5) Controls- Does another player work in the same outlet?
6) Analyze data- Does plugging in the CD player fix the problem.
7) Draw conclusions- does the CD player work now, if so it must have been the cord.
8) Report results- If this were a new experiment we would write a report.

We don’t think about these things- We do this whole process in 2-3 minutes or less. We use the scientific method every day to solve problems.

Define Theory- A well thought out idea about how some part of the natural world works. A theory is a hypothesis that stands the test of time never proven wrong.

NOVA- “Just a Theory.”

What is a law? A statement about how things work in nature that seems to be true all the time. Laws are less likely to change than theories but both are considered facts in science.

What it means to be living

Talon
What is life?

What does it mean to be living?

All living organisms have these characteristics- Organization, Responsiveness and Homeostasis, Energy use, Growth and Development, Reproduction.

Living vs. Non-Living

1) Organization- All organisms are made up of cells.
Cells are the smallest units of organisms
Organisms contain at least 1 cell
Each cell contains DNA- Deoxyriboncleic acid
DNA- contains the programming code for organization and function

2) Responsiveness and Homeostasis -Living things will respond to stimuli
Movement is usually the response
Homeostasis- Regulation of internal environment

3) Energy use- All organisms use food
Food comes directly or indirectly from the sun.
Plants- direct through photosynthesis
Animals- Indirectly through eating plants, or eating animals that ate plants.
Most organisms besides deep-sea archebacteria use oxygen in some way.
Autotroph- Can form organic compounds by itself, can make it’s own food.
Heterotroph- gets food from other organisms.

4) Growth and Development- Raw materials are used for growth
Development- Changes in organisms
Length of life varies from days to thousands of years.

5) Reproduction- All “living” things reproduce.
Varies from once every 20 minutes in some bacteria to every two years

Basic living needs are Space or a place to live and Raw materials, water is number 1.