The Scientific Method

You often experience numbness and pain in the thumb and first two fingers on your right hand. You go to the doctor who suspects that carpal tunnel syndrome is the reason for the numbness and pain. The doctor then orders a simple test to see how fast nerve impulses are moving up and down your arm. The doctor's preliminary diagnosis of carpal tunnel syndrome is a(n)

Hypothesis

A scientific hypothesis must be constructed with which of the following characteristics?

It provides a reasonable explanation to a question and is consistent with current observations; it must also be testable and falsifiable.

Victoria, who is 10 years old, wants to be a zoologist when she grows up because she loves animals. So, she decided to begin her training by "doing something scientific." Specifically, she weighed and measured the lengths of all the earthworms she could find in her yard and recorded the data in a notebook. She then made a graph showing the maximum, minimum, and average weights and heights of the earthworms. Was she doing something scientific?

No, because she had no hypothesis to direct her data collection or interpretation.

Recently, beekeepers have noticed an alarming and sudden disappearance of honeybees from their hives. Some beekeepers and environmentalists worry that crops genetically engineered to contain the gene for the Bt insecticidal toxin may be killing the bees. Without data from a scientific experiment, is it reasonable to state that Bt-containing crops are responsible for the loss of honeybees?

No, because there could be some other unknown or unmentioned factor affecting the survival of honeybees.

Scientific understanding can always be challenged, and even changed, with new ways of observing and with different interpretations. For example, new tools and techniques have resulted in new observations and the discovery of additional information. This has resulted in revised ways of understanding how molecules are moved across the plasma membrane of cells. Hence, there is no certainty in science, only degrees of probability (likelihood) and potential for change. In light of this understanding, which of the following statements is most meaningful?

Scientific knowledge is necessarily contingent knowledge.

Which of the following statements is true?

The scientific method or process can help people make informed medical and environmental decisions.

In science, when a hypothesis or group of hypotheses supported by repeated experimental evidence holds true through time, it can be developed into a ________. It is not a guess. It is not static. It is tentative and dynamic and can be adjusted when new, compelling evidence is discovered. It is typically an overarching explanation that best fits all of the available information or evidence.

Theory

Why do scientists repeat their experiments over and over again?

They must make sure the results were not an accident and that they are repeatable.

Is it possible for scientists to study events that happened or animals/plants that lived millions of years ago?

Yes. Apply the laws of physics and nature that we know exist today to evaluate the evidence of past events. For example, observe modern animal behavior, structure, and function, and compare them to the structures of fossilized animals to deduce the function of the fossilized structures.

Is it important for scientists to communicate their results to fellow scientists?

Yes. The quality and accuracy of the scientific work can be enhanced by input, further review, and possibly even repetition by other scientists working in the same field.

Experimental studies are an effective way of establishing a ________ relationship between two or more aspects of the natural world because they provide a way of testing predicted interaction(s).

cause-effect

Observational studies typically point out correlations between aspects of the natural world, but they do not establish solid ________ relationships.

cause-effect

Which of the following represents conducting an experiment?

dialing a telephone number

When scientists generate a single informed, logical, and plausible explanation for a question and observations of the natural world, they are proposing a scientific

hypothesis

New medications undergo extensive human testing before receiving FDA approval. These tests represent an experiment and variations in the dosage given to participants represents the

independent variable.

Experimentation is the primary, but not only, means used to verify or refute the ________ made by a hypothesis.

predictions

Once supported by a predictable experimental outcome, a scientific hypothesis

still cannot be considered to have been proven true.

A scientific hypothesis must be ________; if not, science cannot evaluate it.

testable

Whenever we ________, we are proceeding scientifically

try to solve a problem by systematically evaluating the plausibility of various solutions

The hypothesis that a common ancestor gave rise to all living organisms is strengthened by what observation?

Almost all cells in all living organisms use DNA to direct their structure, function, and behavior.