BIO 180 EXAM 1 COMPLETE
QUESTIONS WITH VERIFIED ANSWERS
\Q\.What is the difference between a theory and a hypothesis? -
ANSWER-✔Only scale-theories deal with "big ideas" that impact large
parts of the physical or natural world; hypotheses are more focused or
narrower in scope.
\Q\.What is the difference between a hypothesis and a prediction? -
ANSWER-✔A hypothesis is an idea--a testable explanation; a prediction
is something that follows from a hypothesis and that you can measure
\Q\.example of prediction - ANSWER-✔If you boil nutrient broth and
place it in an air-tight flask, no cells will appear in the broth
\Q\.What was important about the experimental design for Pasteur's
flask experiment? -
ANSWER-✔He compared results from two experimental setups which
differed only in the type of flask in which the nutrient broth was placed
,\Q\.How do biologists test their ideas about the natural world? -
ANSWER-✔Scientists make predictions based on hypotheses they have
developed, and then design experiments or other types of studies to
test those predictions
\Q\.Why is it important to perform multiple trials in an experiment --
meaning that you include many test individuals or samples? - ANSWER-
✔To make it more likely that the results are not due to a few unusual
individuals or circumstances
\Q\.The remaining questions refer to this situation: Researchers do an
experiment to test the hypothesis that Douglas fir trees put more
resources into reproduction when they are infected with a fungus that
causes a fatal disease. They establish study plots in a group of 50-year-
old Douglas fir where the disease is not present. At random, they inject
half the trees with the disease-causing fungus. Then they measure how
many cones and seeds are produced by infected versus uninfected
trees.
What prediction follows from the hypothesis? - ANSWER-✔On average,
the infected trees will produce more seeds than uninfected trees
\Q\.Which treatment would be considered the control? - ANSWER-
✔The uninfected trees
,\Q\
\Q\.Why is it important to do the experiment in the same group of
same-aged trees? - ANSWER-
✔To eliminate the possibility that the results are due to differences in
age, soil, moisture, or other relevant variables
\Q\.Why is it important that they assigned trees to the infected versus
uninfected groups at random? - ANSWER-✔If assignment were not
done at random, the result could be do to something other than the
difference in infection
\Q\.If the hypothesis is wrong, and being infected with the fungus has
no impact at all on reproduction, what should they observe? - ANSWER-
✔There will be no difference in the number of seeds produced by
infected versus uninfected seeds
\Q\.A friend says that this experimental design would be better if the
researchers had injected the control group trees with a solution that
was identical to that used in the experimental group, but without the
fungus. Do you agree? - ANSWER-✔Yes. As is, it would be reasonable for
a critic to claim that seed production changed because of the injection
itself, not the presence of the fungus.
.What does the p in "p-value" represent? - ANSWER-✔Probability (of
getting the observed result, just by chance)
, \Q\.Suppose we run a statistical test, and learn that p = 0.01. What does
this mean? - ANSWER-
✔There is a 1 in 100 chance of observing a difference between
treatment groups this extreme if the null hypothesis is correct.
\Q\.If we want to plot the distribution of scores on Exam 1, we should
use a... - ANSWER✔Histogram
\Q\.If we want to plot the exam scores of 1st-year students versus 2nd-
year students, we would use a ... - ANSWER-✔Bar chart
\Q\.If we want to compare the scores of 1st-year and 2nd-year students
using a statistical test, our null hypothesis will be... - ANSWER-✔There is
no difference in exam performance between students in year 1 and 2.
\Q\.If we calculate means (averages) based on scores from 100 1st-year
students and 400 2ndyear students, which is likely to have the smaller
standard error? - ANSWER-✔2nd-year students, because we sampled
more.
\Q\.Which of the following statements is the best way to characterize
the standard error? - ANSWER-✔A measure of how precise our estimate
of the mean is.
QUESTIONS WITH VERIFIED ANSWERS
\Q\.What is the difference between a theory and a hypothesis? -
ANSWER-✔Only scale-theories deal with "big ideas" that impact large
parts of the physical or natural world; hypotheses are more focused or
narrower in scope.
\Q\.What is the difference between a hypothesis and a prediction? -
ANSWER-✔A hypothesis is an idea--a testable explanation; a prediction
is something that follows from a hypothesis and that you can measure
\Q\.example of prediction - ANSWER-✔If you boil nutrient broth and
place it in an air-tight flask, no cells will appear in the broth
\Q\.What was important about the experimental design for Pasteur's
flask experiment? -
ANSWER-✔He compared results from two experimental setups which
differed only in the type of flask in which the nutrient broth was placed
,\Q\.How do biologists test their ideas about the natural world? -
ANSWER-✔Scientists make predictions based on hypotheses they have
developed, and then design experiments or other types of studies to
test those predictions
\Q\.Why is it important to perform multiple trials in an experiment --
meaning that you include many test individuals or samples? - ANSWER-
✔To make it more likely that the results are not due to a few unusual
individuals or circumstances
\Q\.The remaining questions refer to this situation: Researchers do an
experiment to test the hypothesis that Douglas fir trees put more
resources into reproduction when they are infected with a fungus that
causes a fatal disease. They establish study plots in a group of 50-year-
old Douglas fir where the disease is not present. At random, they inject
half the trees with the disease-causing fungus. Then they measure how
many cones and seeds are produced by infected versus uninfected
trees.
What prediction follows from the hypothesis? - ANSWER-✔On average,
the infected trees will produce more seeds than uninfected trees
\Q\.Which treatment would be considered the control? - ANSWER-
✔The uninfected trees
,\Q\
\Q\.Why is it important to do the experiment in the same group of
same-aged trees? - ANSWER-
✔To eliminate the possibility that the results are due to differences in
age, soil, moisture, or other relevant variables
\Q\.Why is it important that they assigned trees to the infected versus
uninfected groups at random? - ANSWER-✔If assignment were not
done at random, the result could be do to something other than the
difference in infection
\Q\.If the hypothesis is wrong, and being infected with the fungus has
no impact at all on reproduction, what should they observe? - ANSWER-
✔There will be no difference in the number of seeds produced by
infected versus uninfected seeds
\Q\.A friend says that this experimental design would be better if the
researchers had injected the control group trees with a solution that
was identical to that used in the experimental group, but without the
fungus. Do you agree? - ANSWER-✔Yes. As is, it would be reasonable for
a critic to claim that seed production changed because of the injection
itself, not the presence of the fungus.
.What does the p in "p-value" represent? - ANSWER-✔Probability (of
getting the observed result, just by chance)
, \Q\.Suppose we run a statistical test, and learn that p = 0.01. What does
this mean? - ANSWER-
✔There is a 1 in 100 chance of observing a difference between
treatment groups this extreme if the null hypothesis is correct.
\Q\.If we want to plot the distribution of scores on Exam 1, we should
use a... - ANSWER✔Histogram
\Q\.If we want to plot the exam scores of 1st-year students versus 2nd-
year students, we would use a ... - ANSWER-✔Bar chart
\Q\.If we want to compare the scores of 1st-year and 2nd-year students
using a statistical test, our null hypothesis will be... - ANSWER-✔There is
no difference in exam performance between students in year 1 and 2.
\Q\.If we calculate means (averages) based on scores from 100 1st-year
students and 400 2ndyear students, which is likely to have the smaller
standard error? - ANSWER-✔2nd-year students, because we sampled
more.
\Q\.Which of the following statements is the best way to characterize
the standard error? - ANSWER-✔A measure of how precise our estimate
of the mean is.
