UNIVERSITY: University of Washington
COURSE: BIOL 180 – Introductory Biology
EXAM TITLE: Midterm Exam Assessment – 2026/2027
Update
TOTAL QUESTIONS: 150
SECTION 1: SCIENTIFIC METHOD & EXPERIMENTAL DESIGN
(Questions 1-25)
1. What is the difference between a hypothesis and a prediction?
A) A hypothesis is a question; a prediction is an answer
B) A hypothesis is an idea; a prediction is something that follows from a hypothesis and can
be measured
C) A hypothesis is always true; a prediction may be false
D) There is no difference; the terms are interchangeable
ANSWER: B
EXPLANATION: A hypothesis is a proposed explanation for a phenomenon. A prediction is a
specific, testable statement derived from the hypothesis about what you expect to observe in an
experiment .
2. Which of the following is a prediction based on the cell theory that all organisms are made of
cells and all cells come from preexisting cells?
A) If you observe pond water under a microscope, you will see moving organisms
B) If you boil nutrient broth and place it in an airtight flask, no cells will appear in the broth
C) All living things require oxygen to survive
D) Cells contain DNA as their genetic material
ANSWER: B
EXPLANATION: Pasteur's experiment tested this exact prediction. If cells only come from
existing cells, then sterilized broth in a sealed flask should remain free of microbial growth .
3. What was important about the experimental design for Pasteur's flask experiment?
A) He used multiple different types of broth
B) He compared results from two experimental setups that differed only in the type of flask
C) He observed the broth under a microscope daily
D) He heated the broth to different temperatures
ANSWER: B
, EXPLANATION: Pasteur used swan-necked flasks that allowed air in but trapped dust and
microbes, compared to flasks with straight necks. The only difference was the flask design,
making it a controlled experiment .
4. How do biologists test their ideas about the natural world?
A) By relying on common sense and intuition
B) By making predictions based on hypotheses and designing experiments to test those
predictions
C) By consulting ancient texts and authorities
D) By observing without any preconceived ideas
ANSWER: B
EXPLANATION: The scientific method involves formulating hypotheses, making testable
predictions, and then conducting experiments or observations to test those predictions .
5. Why is it important to perform multiple trials in an experiment, including many test individuals
or samples?
A) To make the experiment take longer
B) To increase the cost of the research
C) To make it more likely that the results are not due to a few unusual individuals or
circumstances
D) To satisfy funding requirements
ANSWER: C
EXPLANATION: Replication helps account for natural variation and ensures that observed
effects are real and not just due to chance or outliers .
6. A plant physiologist notices a group of trees growing all in one direction, contrary to what she
thinks should happen. This is an example of what part of the scientific method?
A) Hypothesis
B) Conclusion
C) Question
D) Observation
E) Experiment
ANSWER: D
EXPLANATION: The scientific method begins with observation—noticing a phenomenon that
prompts a question .
7. A molecular biologist notices something different in the genetic profile of an individual,
performs careful research, and thinks he discovers a new gene responsible for high blood
pressure in humans. The last step is an example of what part of the scientific method?
A) Hypothesis
B) Observation
, C) Conclusion
D) Experiment
E) Question
ANSWER: C
EXPLANATION: Drawing a conclusion based on evidence and analysis is the final step of the
scientific method .
8. Researchers do an experiment to test the hypothesis that Douglas fir trees put more
resources into reproduction when infected with a fatal fungus. They infect half the trees and
leave half uninfected, then measure cone and seed production. What prediction follows from the
hypothesis?
A) The infected trees will produce more seeds than uninfected trees
B) The uninfected trees will produce more seeds than infected trees
C) Both groups will produce the same number of seeds
D) Infected trees will die before reproducing
ANSWER: A
EXPLANATION: If the hypothesis is correct, infected trees should allocate more resources to
reproduction (more seeds) before they die .
9. In the Douglas fir experiment, which treatment would be considered the control?
A) The infected trees
B) The uninfected trees
C) Both groups are controls
D) Neither group is a control
ANSWER: B
EXPLANATION: The control group is the uninfected trees, which provide a baseline for
comparison .
10. Why is it important to do the experiment in the same group of same-aged trees?
A) To eliminate the possibility that the results are due to differences in age, soil, moisture, or
other relevant variables
B) To make the experiment easier to conduct
C) To ensure all trees are genetically identical
D) To comply with forestry regulations
ANSWER: A
EXPLANATION: Controlling for variables like age and environmental conditions ensures that
any observed differences can be attributed to the treatment (infection) rather than other factors .
11. Why is it important that they assigned trees to infected versus uninfected groups at random?
A) Random assignment is required by ethics committees
, B) If assignment was not random, the result could be due to something other than the
infection
C) Random assignment ensures equal sample sizes
D) Random assignment is easier than systematic assignment
ANSWER: B
EXPLANATION: Randomization prevents bias and ensures that any confounding variables
are equally distributed between groups .
12. If the hypothesis is wrong, and being infected has no impact at all on reproduction, what
should they observe?
A) Infected trees produce more seeds
B) Uninfected trees produce more seeds
C) There will be no difference in the number of seeds produced by infected versus uninfected
trees
D) Both groups will produce zero seeds
ANSWER: C
EXPLANATION: If the null hypothesis (no effect) is true, the two groups should show similar
seed production .
13. In an experiment testing a new drug, researchers give half the participants the drug and half
a placebo. The group receiving the placebo is called the:
A) Experimental group
B) Treatment group
C) Control group
D) Variable group
ANSWER: C
EXPLANATION: The control group provides a baseline for comparison and does not receive
the experimental treatment .
14. What is the purpose of a blind experiment?
A) To keep participants in the dark
B) To prevent participants from knowing which treatment they receive
C) To hide the experimental setup
D) To conduct experiments at night
ANSWER: B
EXPLANATION: Blinding prevents bias, as participants' expectations could influence
outcomes .
15. In a double-blind experiment:
A) Both participants and researchers are blind to treatment assignment
COURSE: BIOL 180 – Introductory Biology
EXAM TITLE: Midterm Exam Assessment – 2026/2027
Update
TOTAL QUESTIONS: 150
SECTION 1: SCIENTIFIC METHOD & EXPERIMENTAL DESIGN
(Questions 1-25)
1. What is the difference between a hypothesis and a prediction?
A) A hypothesis is a question; a prediction is an answer
B) A hypothesis is an idea; a prediction is something that follows from a hypothesis and can
be measured
C) A hypothesis is always true; a prediction may be false
D) There is no difference; the terms are interchangeable
ANSWER: B
EXPLANATION: A hypothesis is a proposed explanation for a phenomenon. A prediction is a
specific, testable statement derived from the hypothesis about what you expect to observe in an
experiment .
2. Which of the following is a prediction based on the cell theory that all organisms are made of
cells and all cells come from preexisting cells?
A) If you observe pond water under a microscope, you will see moving organisms
B) If you boil nutrient broth and place it in an airtight flask, no cells will appear in the broth
C) All living things require oxygen to survive
D) Cells contain DNA as their genetic material
ANSWER: B
EXPLANATION: Pasteur's experiment tested this exact prediction. If cells only come from
existing cells, then sterilized broth in a sealed flask should remain free of microbial growth .
3. What was important about the experimental design for Pasteur's flask experiment?
A) He used multiple different types of broth
B) He compared results from two experimental setups that differed only in the type of flask
C) He observed the broth under a microscope daily
D) He heated the broth to different temperatures
ANSWER: B
, EXPLANATION: Pasteur used swan-necked flasks that allowed air in but trapped dust and
microbes, compared to flasks with straight necks. The only difference was the flask design,
making it a controlled experiment .
4. How do biologists test their ideas about the natural world?
A) By relying on common sense and intuition
B) By making predictions based on hypotheses and designing experiments to test those
predictions
C) By consulting ancient texts and authorities
D) By observing without any preconceived ideas
ANSWER: B
EXPLANATION: The scientific method involves formulating hypotheses, making testable
predictions, and then conducting experiments or observations to test those predictions .
5. Why is it important to perform multiple trials in an experiment, including many test individuals
or samples?
A) To make the experiment take longer
B) To increase the cost of the research
C) To make it more likely that the results are not due to a few unusual individuals or
circumstances
D) To satisfy funding requirements
ANSWER: C
EXPLANATION: Replication helps account for natural variation and ensures that observed
effects are real and not just due to chance or outliers .
6. A plant physiologist notices a group of trees growing all in one direction, contrary to what she
thinks should happen. This is an example of what part of the scientific method?
A) Hypothesis
B) Conclusion
C) Question
D) Observation
E) Experiment
ANSWER: D
EXPLANATION: The scientific method begins with observation—noticing a phenomenon that
prompts a question .
7. A molecular biologist notices something different in the genetic profile of an individual,
performs careful research, and thinks he discovers a new gene responsible for high blood
pressure in humans. The last step is an example of what part of the scientific method?
A) Hypothesis
B) Observation
, C) Conclusion
D) Experiment
E) Question
ANSWER: C
EXPLANATION: Drawing a conclusion based on evidence and analysis is the final step of the
scientific method .
8. Researchers do an experiment to test the hypothesis that Douglas fir trees put more
resources into reproduction when infected with a fatal fungus. They infect half the trees and
leave half uninfected, then measure cone and seed production. What prediction follows from the
hypothesis?
A) The infected trees will produce more seeds than uninfected trees
B) The uninfected trees will produce more seeds than infected trees
C) Both groups will produce the same number of seeds
D) Infected trees will die before reproducing
ANSWER: A
EXPLANATION: If the hypothesis is correct, infected trees should allocate more resources to
reproduction (more seeds) before they die .
9. In the Douglas fir experiment, which treatment would be considered the control?
A) The infected trees
B) The uninfected trees
C) Both groups are controls
D) Neither group is a control
ANSWER: B
EXPLANATION: The control group is the uninfected trees, which provide a baseline for
comparison .
10. Why is it important to do the experiment in the same group of same-aged trees?
A) To eliminate the possibility that the results are due to differences in age, soil, moisture, or
other relevant variables
B) To make the experiment easier to conduct
C) To ensure all trees are genetically identical
D) To comply with forestry regulations
ANSWER: A
EXPLANATION: Controlling for variables like age and environmental conditions ensures that
any observed differences can be attributed to the treatment (infection) rather than other factors .
11. Why is it important that they assigned trees to infected versus uninfected groups at random?
A) Random assignment is required by ethics committees
, B) If assignment was not random, the result could be due to something other than the
infection
C) Random assignment ensures equal sample sizes
D) Random assignment is easier than systematic assignment
ANSWER: B
EXPLANATION: Randomization prevents bias and ensures that any confounding variables
are equally distributed between groups .
12. If the hypothesis is wrong, and being infected has no impact at all on reproduction, what
should they observe?
A) Infected trees produce more seeds
B) Uninfected trees produce more seeds
C) There will be no difference in the number of seeds produced by infected versus uninfected
trees
D) Both groups will produce zero seeds
ANSWER: C
EXPLANATION: If the null hypothesis (no effect) is true, the two groups should show similar
seed production .
13. In an experiment testing a new drug, researchers give half the participants the drug and half
a placebo. The group receiving the placebo is called the:
A) Experimental group
B) Treatment group
C) Control group
D) Variable group
ANSWER: C
EXPLANATION: The control group provides a baseline for comparison and does not receive
the experimental treatment .
14. What is the purpose of a blind experiment?
A) To keep participants in the dark
B) To prevent participants from knowing which treatment they receive
C) To hide the experimental setup
D) To conduct experiments at night
ANSWER: B
EXPLANATION: Blinding prevents bias, as participants' expectations could influence
outcomes .
15. In a double-blind experiment:
A) Both participants and researchers are blind to treatment assignment
