chapter one
Which feature is necessary for a scientific hypothesis?
it is falsifiable
What does the height of the bar labeled "Control group" (on the left side of the graph) show?
the average effectiveness rating of the placebo tea
What step should occur after numerous observations are used to form a sensible, inductively reasoned hypothesis?
hypothesis must be tested
The root means the study of or branch of knowledge about.
-ology
Which source would provide the most credible medical information?
A health website maintained by a regional hospital
A scientific hypothesis is _________
A proposed explanation for an observation.
inductive reasoning
A type of logic in which generalizations are based on a large number of specific observations.
nucleus
Control center of the cell
Which statement would be appropriate scientific hypothesis?
People protected from chilly temperatures catch fewer colds.
If I perform a hypothesis test in which I demonstrate that the prediction I made in question 5 is true, I have __________
Supported the hypothesis. Not falsified by hypothesis
probability
likelihood that a particular event will occur
RNA
A single-stranded nucleic acid that passes along genetic messages
solute
A substance that is dissolved in a solution.
When might bias in an experiment occur?
A technician knows which samples are from the control group.
What outcome results when many independent scientific studies support a well-tested hypothesis?
The hypothesis would be considered a scientific theory.
Scientific studies that indicate that antibiotics are not an effective treatment for colds are more reliable than a blog post that asserts that antibiotics worked for the author of the post.
The process of peer review is an assurance that the information published in scientific journals meets a standard of rigor and accuracy.
What does it mean to say that experimental results are peer reviewed?
The results are analyzed by other scientists before they are published.
nonpolar
Won't dissolve in water. Hydrophobic.
DNA
a complex molecule containing the genetic information that makes up the chromosomes.
primary source
a document or physical object which was written or created during the time under study.
is a proposed explanation for one or more observations, often discerned through inductive reasoning.
a hypothesis
bias
a particular preference or point of view that is personal, rather than scientific.
peer review
a process by which the procedures and results of an experiment are evaluated by other scientists who are in the same field or who are conducting similar research.
natural selection
a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.
hypothesis
a tentative explanation for what has been observed, requires testing to validate
steroids
a type of lipid characterized by a carbon skeleton consisting of four rings with various functional groups attached.
hydrogen bond
a type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule.
testable
able to be observed and measured
model systems
also known as model organisms, these include the small group of species that are the subject of extensive research. They are organisms that adapt well to laboratory situations and findings from experiments on them can apply across a broad range of species. Classic examples include white rats and the fruit fly Drosophila.
double-blind
an observation whose true purpose is hidden from both the observer and the person being observed
statistically significant
an observed effect so large that it would rarely occur by chance
_______ evidence for hypotheses consist of individual's claims about "what worked for them" and is not equivalent to research published in journals.
ancedotal
Experimental _________ occurs when a researcher's expectation affects data collection.
bias
The root means life.
bio-
is the study of living organisms.
biology
polysaccharides
carbohydrates that are made up of more than two monosaccharides
A correlation between two factors does not necessarily mean that one factor _____ a change to the other factor
causes
A statistical test calculates the likelihood that the difference between an experimental and control group is due simply to _____________
chance
Which hypothesis is testable?
cherry is a much stronger word than pine
Bacteria, nematodes, and mice are model systems that allow us to perform ___________ experiments on hypotheses that are difficult to test on humans.
controlled
A relationship between two factors, for instance, between outside temperature and the number of people with active colds in a population is known as a(n) _____________
correlation
The root means to reason out, working from facts.
deduc-
reasoning makes specific predictions based on general principles.
deductive
polar
describes a molecule in which the positive and negative charges are separated
An experiment in which neither the participants in the experiment nor the technicians collecting the data know which individuals are in the experimental group and which ones are in the control group is known as ______________
double blind
ions
electrically charged atoms
lipids
energy-rich organic compounds, such as fats, oils, and waxes, that are made of carbon, hydrogen, and oxygen.
A control in an experiment is a subject that is treated identically to the experimental subject except that the _______ ___________ is not applied.
experimental treatment
variables
factors that can change in an experiment
True or False: A theory based on witness testimony identifying a murderer is a scientific theory.
false
True or false: Any scientific information that appears in a written format is considered a primary source.
false
hydrophobic
having an aversion to water; tending to coalesce and form droplets in water.
The root means under, below, or basis.
hypo-
The intent in a controlled experiment is to eliminate as many alternative _________ as possible.
hypotheses
a ____ is a proposed explanation for how things work.
hypothesis
The root means to rely on reason to derive principles (and also to cause to happen).
induc-
reasoning discerns a general principle from a set of specific observations.
inductive
secondary sources
information consist of descriptions and explanations that are created after a historical event has already taken place
News stories are less likely to be written about research that provides __________ supportive results of a hypothesis test.
less
proteins
made of amino acids coded for by genes. can have structural, transport, or enzymatic roles.
deductive reasoning
making a prediction about the outcome of a test
scientific method
making observations of the world, proposing ideas about how something works, testing those ideas, discarding our ideas in response to the test results
a statement that is testable must be able to be evaluated through ____ of the known universe
measurements
What is the purpose of double-blind experiments?
minimize the effects of human bias on the results
amino acids
monomer subunit of a protein
electrons
negatively charged subatomic particles
sample size
number of individuals in both the experimental and control groups
Scientific papers are not published in most journals until after they have undergone the proves of _____________ review by other scientists in the field.
peer
protons
positively charged subatomic particles
"Statistical significance" is not the same as "______________ significance."
practical
deductive reasoning relies on testing the ____ of a hypothesis test
predictions
Research reports describing the outcomes of a hypothesis test published in scientific journals are referred to as _________ sources.
primary
A statistically significant result is one that has a low __________ of having occurred as a result of chance.
probability
enzymes
protein that catalyzes and regulates the rate of metabolic reactions
if a hypothesis test returns the predicted results, the hypothesis is supported but not definitively ____
proven
a statement that is falsifiable must be able to be
proven wrong
prediction
result expected from a particular test of a hypothesis if the hypothesis were true
Experiments are performed on a small subgroup, or _________ of the population of interest.
sample
placebo
sham treatments in experiments
Instead of reading primary literature, most of us receive our scientific information from ____________ ______________.
sources
The science of ____ is used to evaluate data.
statistics
What is the specialized branch of mathematics that is used to compare data?
statistics
Which item suggests that scientific information on a website may be unreliable?
the site is set up to allow you to buy the product being described.
solvent
the substance in which the solute dissolves
theory of evolution
theory that describes how organisms change over many generations
Why is the scientific method used?
to test ideas about how the natural world works
True or False: Correlational studies that limit the volunteer pool to members of one age group, gender, or occupation can reduce the possibility of alternative hypotheses.
true
A primary source of scientific results is __________
Articles in peer-reviewed journals
When is an experiment considered to be double-blind?
Both participants and researchers are unaware of group member identities.
The principle that certain diseases are caused by infectious agents is a scientific theory.
Certain ideas about how the world works are so well supported by evidence that they are considered central ideas in science.
If a large, randomly assigned group of individuals who take vitamin C do not have fewer colds, on average, than another group that does not take vitamin C, the hypothesis that vitamin C prevents colds is not true
Controlled experiments that eliminate alternative hypotheses for results are the most accurate tests of those hypotheses
Which statement is an example of anecdotal evidence?
Dr. Jackson's personal statement about the effectiveness of his cure for bowel disorders
Experimental subjects are given a pill to test its effectiveness on reducing the duration of a cold. How should the control group be treated?
Give the control group a pill that does not affect the duration of colds.
Consider this hypothesis: "Drinking Echinacea tea reduces the duration and severity of colds." Which statement is the best prediction based on this hypothesis?
If cold sufferers drink Echinacea tea, then they will feel better sooner.
control
In an experiment, the standard that is used for comparison
manipulative studies
In manipulative studies, the researcher controls all the other variables in the experiment, so any health effects observed in the test subjects can be attributed to differences in the independent variable.
natural studies
In other cases, researchers use natural experiments in which the dependent variable (typically a measure of organism health) is measured under differing contexts that are not manipulated
How is a scientific theory different from a scientific hypothesis?
It can explain a large number of observations.
Which of the following is an example of inductive reasoning?
My cow eats grass and my neighbor's cow eats grass; therefore, all cows probably eat grass.
Which hypothesis is testable?
People taking antioxidant supplements have lower cholesterol levels.
One hypothesis states that eating chicken noodle soup is an effective treatment for colds. Which of the following results does this hypothesis predict?
People who eat chicken noodle soup have shorter colds than do people who do not eat chicken noodle soup.
Are there any effective strategies for preventing the common cold?
Science is a process of testing hypotheses, which are ideas about "how things work."
A statement such as "my guardian angel protects me from colds" is not scientific.
Scientific hypotheses must be able to be tested by observations of the natural world and able to be theoretically proved false
Control subjects in an experiment ____________
Should be similar in most ways to the experimental subjects. Should not know whether they are in the control or experimental group. Should have essentially the same interactions with the researchers as the experimental subjects. Help eliminate alternative hypothesis that could explain experimental results.
Suppose that both the researchers and participants involved in this experiment knew who was being given the echinacea tea versus the placebo tea. Which two statements indicate how this might affect the results of the experiment?
Some participants might overstate the echinachea tea's effectiveness because they would expect to feel better. Some researchers might make unconscious, small, but systematic errors in recording results in order to confirm their hypothesis.
Men who take vitamin E supplements have 5% fewer colds than men who do not take vitamin E. This result was statistically significant. However, vitamin E is not commonly sold as a cold preventative.
Statistical significance does not mean "practical significance."
A difference in recovery time from a cold for people who drink echinacea tea and those who drink a different herbal tea may appear large but may not be considered significant.
Statistical tests examine the data collected in an experiment and assign a probability that these data are different than what would be expected as a result of chance