BIOA11H3 Chapter Notes - Chapter 1: Blind Experiment, Dependent And Independent Variables, Falsifiability

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Ology: the study of or branch of knowledge. The scientific theory: an explanation for a set of related observations that is based on well- supported hypotheses from many different types of independent lines of research. Hypothesis: a proposed explanation for the observations made, that of which is testable, falsifiable and poses as a possible answer to a question. Prediction: an estimated outcome of an action, test or investigation. Experiments: sets of actions or observations that collect data or information and test specific hypotheses. Dependent variables: those not changed by the researcher; may change during the experiment and is being measured in the experiment. Controlled experiments: test the effect of a single variable, are limited to possible alternate hypotheses and the differences in its results should be due to the treatment used. Control or control group: these groups of individuals are similar to experimental subjects yet they do not receive the experimental treatment.

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dentifying Dependent and Independent Variables

In order to test a hypothesis and prediction, controlled experiments are used. Controlled experiments involve several necessary components. An independent variable is usually manipulated by a researcher but does not change as a result of the experiment. The changes in the dependent variable may be caused by the experiment (and depend upon the independent variable). Graphs that depict the experimental data list the independent variable on the x-axis while the y-axis shows the dependent variable.

A commonly used mnemonic (memory device) to aid in distinguishing the characteristics of the types of variables is DRY MIX.

D = dependent variable (depends on the other)

R = responding variable (one that changes)

Y = y-axis on a graph

M = manipulated variable (one that is changed by the researcher)

I = independent variable

X = x-axis on a graph

The following sentence is a template to write an if/then statement to be used as a prediction:

If the independent variable is changed [increased, decreased, etc.], then the dependent variable will change in this way [increase, decrease, etc.].

Example: If the amount of available light increases, then plant growth will increase.

Discussion Questions:

Use the tools and examples just discussed to answer the questions about the experiment scenario described next.

Jonah and Tessa noticed that some Leopard frogs by a local river had extra limbs. They decided to check various areas along the river to make more observations. They recorded their observations in their field notebooks. Jonah and Tessa performed a simple laboratory experiment with Leopard frog eggs and river water taken at various spots along the river. They noticed that adult frogs developing from eggs in water collected near an industrial park showed more deformities, but the deformities seemed to be different than those seen on frogs in the natural setting by the river.

Write a prediction that would be appropriate for the experiment scenario.

What would be the independent variable in the experiment?

What would be the dependent variable in the experiment?

What steps should Jonah and Tessa take to ensure that the experiment would be controlled?

Why would they perform these experiments in the laboratory and not in the river?

What conclusion should the researchers derive from their data?

What might be some alternative hypotheses for this situation?

What could be a next step for their investigation?

What other information may help them design future experiments?

choose two nonhuman species that interact with each other, such asbees and flowers, or predator and prey species, or two species thatcompete. Or, you can consider the effect of an environmental factoron living nonhuman organisms, such as the effects of light or soundon plants or animals, or how food preference, or nutrientquantity/quality affect plants or animals. These are just a fewexamples. Your observations may lead you to many other types ofquestions about living organisms, their interactions, andrequirements for life.

Start with an Introduction/Observation and move through the stepsof the scientific method as outlined below. Your paper shouldfollow this format.

Remember, you don't have to actually do the experiment, just writewhat you would do to test your hypothesis. The experiment youcreate to test your hypothesis should contain a control andtreatment group and be detailed enough that it could bereproducible by others.

Observations/Introduction:

Describe your observation.
Include background information about your observations that youhave found using references.
List and cite references using APA format.
Question: Ask a question about the observation that you havemade.

Hypothesis: Write a statement that describes your explanation forthe observation and question.

Prediction: What do you predict as outcomes (results) of thisexperiment? (An if-then statement)

Controlled Experiment and Methods:

Describe the experiment.
Describe variables to be held constant.
Note variable to be tested.
List controls.
Tells what data will be collected.
Describe how only one variable is being tested at a time, whileothers are held constant.
Results: Give the results (data) for the experiment. This will becreated (imagined) by you because you are not actually doing thisexperiment.

Conclusion/Discussion:

Do you reject or accept the hypothesis based on the results?
Discuss what this means in terms of the hypothesis, or need foradditional experiments, or perhaps practical use of the results.

lilacplatypus641

The investigator never begins an experiment without a prediction of its outcome. The prediction is always based on the particular experiment designed to test a specific hypothesis. Predictions are written in the form of if/then statements: "lf the hypothesis is true, then the results of the experiment will beâ¦"; for example, "if cactus spines reduce herbivory, then removal of the spines will result in greater surface area removed by herbivores." Making a prediction provides a critical analysis of the experimental design. If the predictions are not clear, the procedure can be modified before beginning the experiment. For the soybean experiment, the hypothesis was: "Exposure to sulfur dioxide reduces reproduction." What should the prediction be? State your prediction.

To evaluate the results of the experiment, the investigator always returns to the prediction. If the results match the prediction, then the hypothesis is supported. If the results do not match the prediction, then the hypothesis is falsified. Either way, the scientist has increased knowledge of the process being studied. Many times the falsification of a hypothesis can provide more information than confirmation does, since the ideas and data must be critically evaluated in light of new information. In the soybean experiment, the scientist may learn that the prediction is true (sulfur dioxide does reduce reproduction at the concentration tested). As a next step, the scientist may now wish to identify the particular level at which the effect is first demonstrated. Review your hypotheses for the numbered questions. Consider how you might design an experiment to test the first hypothesis. For example, you might measure auditory function by performing hearing tests or observing changes in structures in the ear. The prediction might be:

IF cell phone usage reduces auditory function (a restatement of the hypothesis),

then people who use cell phones will score lower on hearing tests than persons who do not (predicting the results from the experiment).

Now consider an experiment you might design to test the second hypothesis. How will you measure "mental advantage"?

State a prediction for this hypothesis and experiment. Use the if/then format:

The actual test of the prediction is one of the great moments in research. No matter the results, the scientist is not just following a procedure but truly testing a creative explanation derived from an interesting question.â

1. Honeybees provide 80% of the pollination services for crops, including almonds, squash, melons, alfalfa, apples, and pumpkins. Migratory beekeepers transport over 2 million hives to farmland as crops begin to flower. In 2006-2007 beekeepers were alarmed when 50% of the honeybee colonies in 26 states were lost. In fact one of the biggest mysteries was that the bees were not found dead in the hives, but rather were simply gone! Scientists have termed this Colony Collapse Disorder (CCD). They are currently considering three alternative hypotheses: emerging pathogens (viruses, bacteria, and/or fungi), environmental toxins or chemicals; or abduction by humans (or aliens). Using the criteria in Lab Study B, Developing Hypotheses, select the hypothesis you would pursue as a scientist and justify your choice.

BIOA11H3 Chapter Notes - Chapter 1: Blind Experiment, Dependent And Independent Variables, Falsifiability

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