What is Science?

The knowledge obtained by observing natural events and conditions in order to discover facts and formulate laws or principles that can be verified or tested.

Science is a way of thinking, questioning, and gathering evidence.

Limitations to Science

• We are limited by available technology

• The microscope was invented at start of the 1600s. It allowed for the discovery of cells and other microorganisms

Limitations to Science

• Observations must be testable and verifiable

• Observations that cannot be verified or replicated cannot count as scientific evidence.

The Scientific Method

This is the old way…

It’s been modified a bit.

Scientific Thinking

Variables and Controls Experiment: Using independent and dependent variables to find cause-and-effect relationships

– Independent variables are manipulated.

– Dependent variables are observed and measured.

– Constants (control) are conditions that are kept the same.

Identify the independent variable (IV) and dependent variables (DV)

A scientist studies the impact of a drug on cancer.

A scientist studies the impact of withholding affection on rats.

A scientist studies how many days people can eat soup until they get sick.

What are examples of controls in each experiment?

What’s a hypothesis?

• Not a just a random guess to your problem.

• The hypothesis is an Educated Guess about the relationship between the independent and dependent variables.

Hypothesis

• A hypothesis involves researching the problem and finding out what other people have learned, and using that information to help answer the question.

• A hypothesis should be testable!

Practice – Testable or Not?

1. Eating chocolate causes pimples.

2. Dogs are more social than cats.

3. Goldfish prefer the taste of Flakey Fish Food over generic brands.

4. When Sally eats healthy foods and exercises regularly, her blood pressure is 10 points lower than when she does not exercise and eats fatty foods.

Biologists use experiments to test hypotheses Observational (descriptive) studies allow scientists to describe a phenomenon.

Biologists use experiments to test hypotheses Comparative studies allow scientists to collect data to make a comparison

Biologists use experiments to test hypotheses Experimental studies allow scientists to determine what causes a phenomenon.

Manipulates data and

and uses controls.

What is a scientific theory?

• Theories explain a wide range of observations and experimental results.

• A theory is supported by a wide range of scientific evidence.

• Theories can change based on new evidence.

• Are never actually proven

Hypothesis and Theory: What’s the difference?

Hypothesis

A proposed answer to a scientific question.

Hypotheses can be changed to reflect current known understanding.

Theory

Provides explanations of phenomena.

Theories can be modified or changed with new scientific understanding.

A theory was once a hypothesis that is now supported by a lot of data.

Quantitative Data • Quantitative Data or Numerical Data is used to analyze results

using numerical values.

• Quantitative Data is used for making graphs and charts.

• Quantitative Data is essential for analyzing the results of an experiment.

Qualitative Data • When Biologists use purely observational data, they are using

qualitative data.

• Qualitative or Observational Data is often just as important as Quantitative or Numerical Data.

International System of Measurement or SI • All measurement in Biology or any Science experiments need

to be in SI units.

• Since this measurement system is used around the world data can be analyzed by any scientist.

• The basic units of SI are the meter (length), liter (volume), gram (mass), second (time), and Celsius (temperature).

International System of Measurement or SI

• SI Units most commonly used in Biology are:

• cm

• µm – micrometer used to measure microscopic organisms

• mL

• ° C

• g

• What lab equipment would use the above SI units?