Biology Lab- Scientific Method

elements of an experiment

1. Define and give examples of dependent, independent and standardized variables. 2. Identify the variables in an experiment 3. Explain what controls are and why they are used. 4. Explain replication and tell why it is used.

Methods

Measuring the dependent variable. Ex.) If all we want to do is measure growth of a plant, we can do it by fresh weight of stem and leaves, dry weight of steam and leaves

Scientific Method

OBSERVATION of the world around us, leads to formation of HYPOTHESES (generalizations), leads to tests of the hypotheses- EXPERIMENTS.

levels of treatment

Once the investigator has decided on a hypothesis to be tested, they must also determine how to vary the independent variable: know as THIS. Ex.) 0, 5, 10, 20 grams of fertilizer per 100 feet.

Three major ways of knowing

Philosophy, Religion, Natural Philosophy (Science)

hypothesis

This is the testable statement. It must be possible to falsify this statement. The statement should involve the dependent variable and be in the form of a prediction. Also stated as null hypothesis. "NULL" because the prediction is generally that nothing will happen as a result of the experimental treatment. If something happens as a result of the treatment then the hypothesis is falsified or rejected. Ex.) In a plant growth experiment the hypothesis might take this form: "The addition of fertilizer to the soil WILL NOT MAKE ANY CHANGE in the total height of the plants as measured by total height on the 16th day of growth."

standardized variables

Those variables that are maintained as constants in all treatments or variations of the independent variables. Maintaining these conditions as fixed permits the experimenter to determine if the independent variable is having an effect. Ex.) If the variable is the amount of fertilizer added, then light must be equal for all of the plants, the soil must be the same, temperatures, watering, ect.

independent variables

What is DELIBERATELY varied during the experiment, the condition being tested. Ex.) For plant growth it might be the amount of light, number of hours of light per day, quantity of fertilizer added, ect. It is not always possible for the experimenter to control the variable. "X axis"

Dependent Variable

What is measured in an experiment. It is what the experimenter thinks will change in the system under the experimental conditions. Ex.) If studying plant growth, the dependent variable is height. "Y axis"

Religion

appear to depend on divine revelation of knowledge. BELIEF- that the book is indeed DIVINE revelation. Revealed wisdom is stored in book or oral tradition. Religion makes no progress- any progress requires a new divine revelation; without divine revelation it is not part of the religion (you cannot add to or subtract from the doctrine)

0.3048

feet to meters

2.54

inches to centimeters

Philosophy

logic/reasoning by an individual. Others individuals adhere or not-swayed by the strength of the reasoning. BELIEF= believe in the truth of the logic. Each philosopher starts anew and only makes their own progress without benefit of predecessors.

1.6093

miles to kilometers

Natural Philosophy (Science)

observations and hypotheses made on our natural surroundings. BELIEF- That there is an external reality & That our senses accurately portray that external reality most of the time. Science can progress from what is known to what is unknown.

0.4536

pounds to kilograms

Replication

repeated/done multiple times. This reduces the probability that a result happened by chance and supports the idea that the result is an actual result of the independent variable.

control treatments

the independent variable is eliminated or set at a standard value. The results of the control will then be compared to the results of the treatments. Ex.) In plant growth, no addition of fertilizer would be the control.