Unit 1 – Basic Biological Principles (BIO.A.1)

• BIO.A.1.1 – Explain the characteristics common to all organisms

• BIO.A.1.2 - Describe the relationships between structure and function at biological levels of organization

Unit 1: Lesson 1

• Science• The Scientific Method • Biological Sciences • Biological Tools

What is Science?• The goal of science is to investigate and

understand the natural world, to explain events in the natural world, and to use those explanations to make useful predictions.

Science…..• deals only with the natural world.• uses information that is carefully collected and organized to look for patterns and connections.• proposes explanations for natural events that can be tested by examining evidence.

Think like a scientist…..• Use all of your senses to make observations• Gather data based on your observations. Quantitative Data can be counted or measured. (numerical) Qualitative Data is descriptive. (observational)• Make inferences - logical interpretations of your data• Propose a testable hypothesis – a scientific explanation for a set of data

Science is an ongoing process – new tools, new techniques, new discoveries are made all the time.

Sometimes these new discoveries, tools & techniques are questioned by the non-scientific community. Politics, religion, ethics and values must be considered.

Be skeptical. Be open-minded!

The Scientific Method, Conducting Experiments, Microscopes, and Tools of

Biology

Scientific Method

The Scientific Method• Is a series of logical steps used

to make assumptions about science.

• There is no universal way to do science.

• However, in order to conduct valid research and get accurate results, some form of logic with procedures must be followed.

1. Define the Problem• Problems should be as specific as possible.

– Ex: Does acid rain harm living things? (too vague)– Ex: What effect does acid rain have on the early growth of tadpoles? (more specific)

2. Research the Problem• You must have some knowledge on the

subject being covered.

– Ex: Tadpole growth, acid rain, pH scale, typical levels of acid rain.

3. Develop a Hypothesis

• Educated Guess (based on your research)• If….then…. Statements are very good way to form

a hypothesis.

– Ex: If tadpoles are exposed to acid rain, then they will be smaller in size.

4. Develop a Controlled Experiment• Contains only one experimental variable,

sometimes called the Independent Variable• All other variables must be controlled!

– Ex: Two identical tanks with frog eggs. One tank has tap water, the other tank has collected acid rain water.

5. Collect and Analyze Data• Data = any piece of information collected or calculated during the experiment

Quantitative vs Qualitative– Daily observation, measurements, etc..– Data Tables and Graphs are an excellent way

to display data

6. Come up with a Conclusion• May or may not support your hypothesis• Must be based on your data• If hypothesis proves to be wrong, don’t change

the data !!!

7. Repeat, Verify and Publish Results• Most modern science is worked on for years to

validate the results.• Publication is the best way to convey science to

others that are interested.

• A theory may be developed – explanation of a repeated observation from experiments

• Note: Laws can not be disproved by normal physical means. They are rarely used in Biology.

Controlled Experiments

Variables• All experiments have variables

– factors that are used and tested in attempting to prove a hypothesis

• Controlled Experiments are designed to be identical except for one factor… the experimental variable.

• Controlled Experiments contain two groups: 1. The Experimental Group 2. The Control Group (used for comparison)

Independent Variable• Often called the experimental variable

• This is the variable being tested for.

• It is the one variable that the experimenter has control over.

• It is usually present in the experimental group and not the control group.

Examples:

1) We could water a set of similar plants with different amounts of water and measure the heights of the

plants after one month.

2) We could change the concentration of acid to find out how it affects the speed of a reaction.

3) We could drop a ball from different height to find out how long it takes to hit the ground.

Dependent Variable• The variable in the experiment that is

usually measured or observed.

• It most cases, it usually is the outcome or results of the experiment.

• The experimenter has no control over the outcome.

Examples:

1) We could water a set of similar plants with different amounts of water and measure the heights of the

plants after one month.

2) We could change the concentration of acid to find out how it affects the speed of a reaction.

3) We could drop a ball from different height to find out the time it takes to hit the ground.

Problem: How does acid rain effect the growth of tadpoles ?

Collect InformationResearch …. … Tadpole growth & development … Acid Rain … Acids, the pH scale

Hypothesis: If tadpoles are exposed to acid rain, then it will take longer for them to turn into adult frogs.

Experimental Group: Aquarium Tank with 20 tadpoles filled with acid rain water that has a pH of 4

Control Group: Aquarium tank with 20 tadpoles filled with distilled water that has a pH of 7

Independent Variable: The pH of the water placed in each aquarium.

Dependent Variable: The amount of time it takes the tadpoles to change into frogs.

Collecting Data• Quantitative Data – numerical data• Qualitative Data – not numerical

(preferences, feelings, levels of agreement)

• Individual Data – single measurement• Derived Data - Calculated

Examples of Derived Data Mean = Average Median = Middle Value or Average of two middle numbers Mode = The number that occurs most often in a data set Net = Added Total (Sum) Percentage = Part of a Whole

Organizing Data – Data Tables• Used to logically

order and present accumulated data from experiments

• Should always have a title that reflects what is in the table

• Should always have labeled columns and rows with units of measurement noted.

Organizing Data - Graphs• Used to visually display data• Makes it easy to see

differences, patterns, and relationships.

• Line, Pie, Bar

Line Graph• Plotted points used to draw a line• Works best with data that is sequenced or

continuous

Bar Graph• Columns are used to compare pieces of data or

categories of data that are not necessarily related or sequential.

Pie Graph• Used to compare data and show a

percentage of a group.

All graphs should …… have a title that reflects the variables… have labels (data means nothing without a label)… have units of measurements noted… be scaled appropriately… be neat and have color or shading to enhance

clarity… have a key if necessary

Now that all of the data has been collected and organized. It must be analyzed and interpreted.

WHAT DO ALL THE NUMBERS MEAN??The collection of data is the easy part, the analysis and interpretation are the sources of confusion. “The numbers don’t lie” is a phrase we always hear, but numbers can mislead.

Be skeptical, be curious … think like a scientist!