Intro to Biology

Purpose: to introduce the recurring themes of this course and describe the mechanisms by which science is explored

What is Science???

• Study of a topic that seeks to understand and explain the universe around us. • Often requires experimentation and must

be supported by evidence

You notice something - Pushing the button did not turn the flashlight on. (Observation)

It makes you wonder, why? Or How? - What is wrong with the flashlight that it didn’t turn on?(Ask a Question/State your Problem)

You think about it for a while and then propose a possible explanation. – The batteries are dead (Form a Hypothesis)

You decide to test out your idea – Replace the batteries in the flashlight, and push the button again (Experiment)

Does it look like your hypothesis was right?

Support of Hypothesis

After many repetitions of the tests by you and other “observers”, all of which continue to support your

hypothesis….

Hypothesis becomes a Theory

You look at the results of your tests – did the flashlight turn on? (Data analysis)

Or do your results suggest something else?

Scientific Method

New Hypothesis

You can make a testable prediction that will be true – If I replace the batteries, the flashlight will work. (Make a prediction)

Key Terms to Remember• Hypothesis

• A testable educated answer to a question

• Experiment• Process used to generate data that can

support or disprove hypothesis.

• Variable• Something that changes during the course of an

experiment.

Types of experiments: • Controlled Experiments:

• Examines how changing one variable can affect another

• Only manipulates 1 variable while keeping all others the same;

• Comparative/Field Studies:

• We don’t manipulate any variables• Look at groups that are inherently different

and measure effect of those differences

3 Kinds of Variables

• Independent Variable – something that is changed by the scientist• What is tested• What is manipulated

3 Kinds of Variables

• Dependent Variable – something that might be affected by the change in the independent variable• What is observed• What is measured• The data collected during the investigation

3 Kinds of Variables

• Controlled Variable – a variable that is not changed• Also called constants• Allow for a “fair test”

Easy to identify independent and dependent variables• Take every experiment and phrase it

as follows:

• We are testing the effect of _________ on _____________.

• The first blank is the independent variable and the second is the dependent.

You try it!Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle.

• Independent Variable –

• Dependent Variable –

• Controlled Variables –

Controlled Experiments• Controlled experiments have at least TWO set-ups.

• Experimental Group(s)• One or more treatments of the independent variable is tested

• Control Group• Independent variable is NOT present/Normal situation.• DO NOT CONFUSE THIS WITH CONTROLLED VARIABLES!!!!!

• Example• What would be a good control group for the following

experiment?• At student tests whether playing Appalachian Folk Music during

studying will help performance on math tests.

Data and Conclusions

• Data• What you observe and record• Dependent Variable

• Conclusions• What the data/results suggest about the

initial hypothesis Interpretation

Other things to consider in experiments

• Sample Size• Test Subject Demographics• Bias • Margin of Error• Statistically Significant Differences

Theory

•A theory is the most well supported and agreed upon explanation for a phenomenon based on CURRENT evidence.

Can a theory change??What is the relationship between

theories and facts???

Segue into Life Science……

• There are many different fields of science, ranging from particle physics, to organic chemistry to evolutionary ecology. All of these fields however, share in the same fundamental scientific processes discussed. The scientific methodology is universal in all these fields.

Biology: study of living things

how they work how they interact with the environment how they change over time Included in this is are many specific areas of study

such as medicine, nutrition, genetics, physiology, microbiology, ecology, environmental studies, evolution and biochemistry (just to name a few).

Living vs. Non-living•Two main components of the environment.•Abiotic-

•Examples?

•Biotic –•Examples?

ENERGY IS A BIG DEAL•Living things must obtain nutrients and energy

•Why do we need to do this?

•The “stuff” we eat/use for energy moves us into the abiotic world and a little chemistry

Chemistry explains what life is made of!

•We are made of matter - anything that has mass (takes up space no matter how small).

•We use Energy to do work – Energy isn’t matter, however we can get it from matter

•All the matter is made up of tiny particles called atoms

WHAT REALLY MATTERS FOR LIFE???

•Only a few types of atoms (called elements) are used to make up most of a living thing•CHNOPS are the major ones!

•These atoms are not yours alone! They have been shared with the environment and other living things!

Elements in Earth’s crust vs. humansEarth’s crust Human BodyELEMENT % composition ELEMENT % composition

Oxygen 46 Oxygen 65

Silicon 27.7 Carbon 18Aluminum 8.1 Hydrogen 10Iron 5.0 Nitrogen 3Calcium 3.6 Calcium 1.5Sodium 2.8 Phosphorus 1.0Potassium 2.6 Potassium 0.35Magnesium 2.1 Sulfur 0.25All others 1.5 Sodium 0.15

Plus Trace Elements

•The atmosphere: •79% nitrogen•20% oxygen•1% other gases. The other gases include Argon, (Ar), carbon dioxide (CO2), methane (CH4) as well as many others.

How do we share?These major atoms are recycledconstantly

So certain elements can cycle between abiotic and biotic factors!

Other important Abiotic factors

•Water: essential to life and is recycled

Other important Abiotic factors

•Soil: primarily made of decomposed living things

•Earth/rock: fits into geology, but essential to formation and structure of our planet• Even rocks cycle. How??

In other words, the same types of atoms can be combined differently to make both living and non-living things!