BIOL 241 - Lab Exam Actual study set
with Questions and correct/verified
Answers
The Scientific Method - ANSW-Steps:
1. Observation leading to question
2. Formulate a hypothesis
3. Test hypothesis using an experiment containing a control and an experimental trial
4. Collect and interpret the results
5. If the evidence...
a) rejects the hypothesis: revise the hypothesis
b) fails to reject the hypothesis, repeat testing of hypothesis OR refine the hypothesis and go through the
process again
6. If the evidence fails to reject the hypothesis numerous time, you form a scientific theory
Observation - ANSW-Act of viewing the world around us. Allows us to formulate questions.
Hypothesis - ANSW-A proposed explanation of a phenomenon, pattern, or set of observations. Should be
specific; too broad --> difficult to test thoroughly.
Can hypotheses be proven? - ANSW-No! We can only reject them or fail to reject them. Future
experiments could one day reject them.
Null hypothesis - ANSW-Assumes that the experimental treatment and control treatment will not have a
significant difference.
I.e., assumes experimental treatment will have no effect.
Alternate hypothesis - ANSW-States there is a significant difference between the experimental and
control groups.
I.e., assumes experimental treatment had an effect
Experiment - ANSW-A test formulated with clear predictions of what will happen if the hypothesis is
rejected versus the outcome if it is not.
, Independent variable - ANSW-Variable of interest which is manipulated by the experimenter (cause).
Dependent variable - ANSW-Factor which responds to the changes in the independent variable (effect).
Control treatment - ANSW-A treatment without the independent variable but with all other constants.
Used to confirm experimental set-up does not have an effect on the dependent variable and determine
whether or not experimental treatment causes a significant difference in the dependent variable.
Experimental treatment - ANSW-Treatment with the manipulated/independent variable + constants.
Used to determine if the independent variable has a significant effect on the dependent variable.
Constants - ANSW-Conditions/factors which remain the same in each treatment (control +
experimental). All other factors except for the manipulated variable should remain constant between the
treatments.
Replication - ANSW-Experiment run several times to ensure the results are reliable.
x-bar - ANSW-Sample mean
SEM - ANSW-Standard error of the mean
sqrt((summation from 1 to n of (x-bar - xi)^2)/(n(n-1)))
Not the same as SD. Only tells you if the means are the same or different, not significance.
SEM tells us the range within which we are confident the true mean lies.
Setting up a Table (key points) - ANSW-Review Appendix 1
Reasons for variability (3) - ANSW-1) Level of imprecision in measurements
2) Individual differences in a POP
3) Sample represents a small portion of the entire POP
To reduce variability (2) - ANSW-1) Increased sample sizes
2) Multiple replicates
Steps after rejecting a hypothesis - ANSW-1) Critical look at experimental design, possibly to improve
accuracy and prevent a potential false rejection.
2) Revision of original hypothesis based on what you learned in the experiment.
Publication - ANSW-Once a hypothesis has failed rejection in a series of tests, it is submitted to a
scientific journal for publication. Before publishing, it is peer-reviewed by other scientists.
Once published, becomes available for other researchers to critique and verify the results.
Peer Review - ANSW-Once a paper is submitted for publication, it is peer-reviewed by other scientists
(assessed on basis of logical thought, factual accuracy, methodology, and interpretation of results).
with Questions and correct/verified
Answers
The Scientific Method - ANSW-Steps:
1. Observation leading to question
2. Formulate a hypothesis
3. Test hypothesis using an experiment containing a control and an experimental trial
4. Collect and interpret the results
5. If the evidence...
a) rejects the hypothesis: revise the hypothesis
b) fails to reject the hypothesis, repeat testing of hypothesis OR refine the hypothesis and go through the
process again
6. If the evidence fails to reject the hypothesis numerous time, you form a scientific theory
Observation - ANSW-Act of viewing the world around us. Allows us to formulate questions.
Hypothesis - ANSW-A proposed explanation of a phenomenon, pattern, or set of observations. Should be
specific; too broad --> difficult to test thoroughly.
Can hypotheses be proven? - ANSW-No! We can only reject them or fail to reject them. Future
experiments could one day reject them.
Null hypothesis - ANSW-Assumes that the experimental treatment and control treatment will not have a
significant difference.
I.e., assumes experimental treatment will have no effect.
Alternate hypothesis - ANSW-States there is a significant difference between the experimental and
control groups.
I.e., assumes experimental treatment had an effect
Experiment - ANSW-A test formulated with clear predictions of what will happen if the hypothesis is
rejected versus the outcome if it is not.
, Independent variable - ANSW-Variable of interest which is manipulated by the experimenter (cause).
Dependent variable - ANSW-Factor which responds to the changes in the independent variable (effect).
Control treatment - ANSW-A treatment without the independent variable but with all other constants.
Used to confirm experimental set-up does not have an effect on the dependent variable and determine
whether or not experimental treatment causes a significant difference in the dependent variable.
Experimental treatment - ANSW-Treatment with the manipulated/independent variable + constants.
Used to determine if the independent variable has a significant effect on the dependent variable.
Constants - ANSW-Conditions/factors which remain the same in each treatment (control +
experimental). All other factors except for the manipulated variable should remain constant between the
treatments.
Replication - ANSW-Experiment run several times to ensure the results are reliable.
x-bar - ANSW-Sample mean
SEM - ANSW-Standard error of the mean
sqrt((summation from 1 to n of (x-bar - xi)^2)/(n(n-1)))
Not the same as SD. Only tells you if the means are the same or different, not significance.
SEM tells us the range within which we are confident the true mean lies.
Setting up a Table (key points) - ANSW-Review Appendix 1
Reasons for variability (3) - ANSW-1) Level of imprecision in measurements
2) Individual differences in a POP
3) Sample represents a small portion of the entire POP
To reduce variability (2) - ANSW-1) Increased sample sizes
2) Multiple replicates
Steps after rejecting a hypothesis - ANSW-1) Critical look at experimental design, possibly to improve
accuracy and prevent a potential false rejection.
2) Revision of original hypothesis based on what you learned in the experiment.
Publication - ANSW-Once a hypothesis has failed rejection in a series of tests, it is submitted to a
scientific journal for publication. Before publishing, it is peer-reviewed by other scientists.
Once published, becomes available for other researchers to critique and verify the results.
Peer Review - ANSW-Once a paper is submitted for publication, it is peer-reviewed by other scientists
(assessed on basis of logical thought, factual accuracy, methodology, and interpretation of results).
