WESTERN GOVERNORS UNIVERSITY | INTRODUCTION TO BIOLOGY (C190) | OBJECTIVE ASSESSMENT (OA)
STUDY PREPARATION
Bio WGU Study for OA C190 2026/2027
Complete Questions and Answers (100% Correct)
145 verified exam-style questions with high-confidence rationales for every item | Aligned to the 2026-2027 WGU C190
Objective Assessment competency blueprint | Competency-labeled items, OA test-taking strategy notes, and high-frequency
topic weighting for targeted study and review
145 8 / 20
Total Questions Content Sections Percent Recall / Percent Scenario-
No More, No Less Q1 through Q145 Application / Analysis Based / Direct Recall
Section 1 | Scientific Inquiry and Biology Foundations
Questions 1-16 | Scientific Method, Experimental Design, Characteristics of Life, and Biological Organization
Q1: A student notices that houseplants placed on a sunny windowsill grow taller than identical plants
kept in a dark closet. According to the scientific method, what should the student do FIRST after
making this observation?
A. Form a testable hypothesis that explains the growth difference [CORRECT]
B. Publish the observation in a scientific journal as a final finding
C. State a final conclusion about the mechanism of photosynthesis
D. Discard any data that does not support the observed trend
Correct Answer: A
Rationale: [Recall | Competency: Scientific Method] The scientific method begins with an observation, which
immediately leads to a testable, falsifiable hypothesis. Publishing and drawing final conclusions come only after
experiments generate and analyze data, and discarding unwanted data is a serious form of bias that invalidates an
investigation. OA Tip: memorize the standard sequence of observation, question, hypothesis, experiment, data
analysis, and conclusion, because the OA frequently asks which step comes first or next.
Q2: Which statement is a properly formulated scientific hypothesis?
A. Plants are beautiful additions to any classroom environment.
B. If soil nitrogen levels are increased, then bean plants will grow taller over a two-week
period. [CORRECT]
C. Do nitrogen levels affect how tall bean plants grow?
D. Nitrogen is the most important substance on Earth.
WGU C190 Introduction to Biology | OA Study Preparation 2026/2027 1
,Bio WGU Study for OA C190 2026/2027 Complete Questions and Answers (100% Correct)
Correct Answer: B
Rationale: [Application | Competency: Scientific Method] A valid hypothesis must be testable, falsifiable, and
predictive, and the if-then format in choice B makes a measurable prediction that an experiment can support or
refute. Choices A and D are untestable value judgments rather than scientific claims, and choice C is a research
question, not a predictive statement. OA Tip: on the OA, identify hypotheses by asking whether the claim can be
proven wrong by evidence; opinions and open questions fail that test.
Q3: A student tests whether the amount of fertilizer affects tomato plant height by giving five plants
0 g, five plants 5 g, and five plants 10 g of fertilizer, while keeping water, sunlight, and soil identical.
What is the independent variable in this experiment?
A. The height of the tomato plants
B. The amount of water each plant receives
C. The amount of fertilizer applied to each group [CORRECT]
D. The total number of plants in the experiment
Correct Answer: C
Rationale: [Application | Competency: Experimental Design] The independent variable is the factor the
researcher deliberately changes between groups, which here is the fertilizer amount set at 0 g, 5 g, and 10 g. Plant
height is the dependent variable being measured, while water, sunlight, and soil are standardized variables held
constant. OA Tip: remember that the independent variable is what the experimenter controls, and the dependent
variable is the measured response that depends on it.
Q4: In the same fertilizer experiment, which measurement serves as the dependent variable?
A. The height of the tomato plants at the end of the study [CORRECT]
B. The brand of fertilizer used on each group
C. The amount of sunlight each plant receives daily
D. The species and variety of tomato plant used
Correct Answer: A
Rationale: [Application | Competency: Experimental Design] The dependent variable is the outcome the
scientist measures to see whether it responds to the manipulated factor, and here the measured outcome is plant
height. The fertilizer brand, sunlight, and plant variety are either standardized conditions or constants, not
measured responses. OA Tip: a quick check is to phrase the experiment as the effect of X (independent) on Y
(dependent); whatever fills the Y slot is the dependent variable.
WGU C190 Introduction to Biology | OA Study Preparation 2026/2027 2
,Bio WGU Study for OA C190 2026/2027 Complete Questions and Answers (100% Correct)
Q5: A student claims that a new plant food makes ferns grow faster. She treats one fern with the
plant food and measures its growth for two weeks, but she never grows an untreated fern for
comparison. What is the most serious flaw in her investigation?
A. The experiment lasted too long to show any effect
B. Ferns are known not to respond to any plant food
C. She measured growth in centimeters instead of millimeters
D. The investigation lacks a control group for comparison [CORRECT]
Correct Answer: D
Rationale: [Analysis | Competency: Experimental Design] Without an untreated control group, the student
cannot know whether the treated fern grew differently from a normal fern, so any growth she records cannot be
attributed to the plant food. The duration, the unit of measurement, and the biological responsiveness of ferns are
not the central flaw. OA Tip: when an OA design question asks for the most serious flaw, look first for a missing
control group or missing replication, the two most commonly tested weaknesses.
Q6: In a controlled experiment, what is the primary purpose of the control group?
A. To receive every treatment being tested in the experiment
B. To provide a baseline for comparison under normal, untreated conditions [CORRECT]
C. To increase the number of variables operating in the experiment
D. To guarantee that the original hypothesis will be proven true
Correct Answer: B
Rationale: [Recall | Competency: Experimental Design] The control group experiences normal conditions
without the experimental treatment, establishing the baseline against which treated groups are compared. Choice
A describes experimental groups, choice C states the opposite of what controls do, and choice D is impossible
because experiments never guarantee or prove a hypothesis. OA Tip: pair this definition with the fact that
experiments support or fail to support hypotheses but never prove them absolutely.
Q7: In the fertilizer experiment, keeping water, sunlight, soil type, and pot size identical across all
three groups serves what purpose?
A. It guarantees that the fertilized plants will grow taller than the others
B. It eliminates the need to collect or analyze any data
C. It converts the dependent variable into an independent variable
D. It prevents other factors from influencing the measured results [CORRECT]
WGU C190 Introduction to Biology | OA Study Preparation 2026/2027 3
, Bio WGU Study for OA C190 2026/2027 Complete Questions and Answers (100% Correct)
Correct Answer: D
Rationale: [Application | Competency: Experimental Design] Standardized (controlled) variables are held
constant so that fertilizer amount remains the only plausible cause of any difference in plant height. Holding
conditions constant does not guarantee outcomes, remove the need for data, or alter the roles of the variables. OA
Tip: the OA expects you to distinguish three variable types quickly: independent (manipulated), dependent
(measured), and standardized (held constant).
Q8: After measuring 50 plants, a student finds that fertilized plants average 4 cm taller than
unfertilized plants. Which conclusion is scientifically appropriate?
A. Fertilizer causes all plants to grow exactly 4 cm taller
B. The hypothesis is proven true beyond all possible doubt
C. The experiment failed because individual plants grew different amounts
D. The data support the hypothesis, but the effect should be retested [CORRECT]
Correct Answer: D
Rationale: [Analysis | Competency: Data Analysis and Conclusions] Scientific conclusions state that data
support a hypothesis, because natural variation and limited sampling mean results are always provisional and
benefit from replication. The word all overstates the finding, proven is a red-flag word the OA uses to mark
wrong answers, and variation among individuals is normal rather than a failure. OA Tip: treat absolute words
such as prove, all, never, and always as signals of incorrect answer choices on data-interpretation items.
Q9: In a clinical drug trial, neither the participants who receive pills nor the researchers recording
outcomes know who received the real drug and who received a placebo. How does this double-blind
design improve the study?
A. It reduces bias from the expectations of both participants and researchers [CORRECT]
B. It allows the researchers to skip statistical analysis of the results
C. It ensures that every participant receives the active drug
D. It removes the need for any control group in the trial
Correct Answer: A
Rationale: [Application | Competency: Bias Reduction] Blinding prevents the placebo effect in participants and
observer bias in researchers, so measured differences are more attributable to the drug itself. Blinding does not
replace statistics, does not give everyone the drug, and never substitutes for a control group. OA Tip: link design
vocabulary together for the OA: placebo controls expectation, blinding controls bias, and replication controls
random error.
WGU C190 Introduction to Biology | OA Study Preparation 2026/2027 4
STUDY PREPARATION
Bio WGU Study for OA C190 2026/2027
Complete Questions and Answers (100% Correct)
145 verified exam-style questions with high-confidence rationales for every item | Aligned to the 2026-2027 WGU C190
Objective Assessment competency blueprint | Competency-labeled items, OA test-taking strategy notes, and high-frequency
topic weighting for targeted study and review
145 8 / 20
Total Questions Content Sections Percent Recall / Percent Scenario-
No More, No Less Q1 through Q145 Application / Analysis Based / Direct Recall
Section 1 | Scientific Inquiry and Biology Foundations
Questions 1-16 | Scientific Method, Experimental Design, Characteristics of Life, and Biological Organization
Q1: A student notices that houseplants placed on a sunny windowsill grow taller than identical plants
kept in a dark closet. According to the scientific method, what should the student do FIRST after
making this observation?
A. Form a testable hypothesis that explains the growth difference [CORRECT]
B. Publish the observation in a scientific journal as a final finding
C. State a final conclusion about the mechanism of photosynthesis
D. Discard any data that does not support the observed trend
Correct Answer: A
Rationale: [Recall | Competency: Scientific Method] The scientific method begins with an observation, which
immediately leads to a testable, falsifiable hypothesis. Publishing and drawing final conclusions come only after
experiments generate and analyze data, and discarding unwanted data is a serious form of bias that invalidates an
investigation. OA Tip: memorize the standard sequence of observation, question, hypothesis, experiment, data
analysis, and conclusion, because the OA frequently asks which step comes first or next.
Q2: Which statement is a properly formulated scientific hypothesis?
A. Plants are beautiful additions to any classroom environment.
B. If soil nitrogen levels are increased, then bean plants will grow taller over a two-week
period. [CORRECT]
C. Do nitrogen levels affect how tall bean plants grow?
D. Nitrogen is the most important substance on Earth.
WGU C190 Introduction to Biology | OA Study Preparation 2026/2027 1
,Bio WGU Study for OA C190 2026/2027 Complete Questions and Answers (100% Correct)
Correct Answer: B
Rationale: [Application | Competency: Scientific Method] A valid hypothesis must be testable, falsifiable, and
predictive, and the if-then format in choice B makes a measurable prediction that an experiment can support or
refute. Choices A and D are untestable value judgments rather than scientific claims, and choice C is a research
question, not a predictive statement. OA Tip: on the OA, identify hypotheses by asking whether the claim can be
proven wrong by evidence; opinions and open questions fail that test.
Q3: A student tests whether the amount of fertilizer affects tomato plant height by giving five plants
0 g, five plants 5 g, and five plants 10 g of fertilizer, while keeping water, sunlight, and soil identical.
What is the independent variable in this experiment?
A. The height of the tomato plants
B. The amount of water each plant receives
C. The amount of fertilizer applied to each group [CORRECT]
D. The total number of plants in the experiment
Correct Answer: C
Rationale: [Application | Competency: Experimental Design] The independent variable is the factor the
researcher deliberately changes between groups, which here is the fertilizer amount set at 0 g, 5 g, and 10 g. Plant
height is the dependent variable being measured, while water, sunlight, and soil are standardized variables held
constant. OA Tip: remember that the independent variable is what the experimenter controls, and the dependent
variable is the measured response that depends on it.
Q4: In the same fertilizer experiment, which measurement serves as the dependent variable?
A. The height of the tomato plants at the end of the study [CORRECT]
B. The brand of fertilizer used on each group
C. The amount of sunlight each plant receives daily
D. The species and variety of tomato plant used
Correct Answer: A
Rationale: [Application | Competency: Experimental Design] The dependent variable is the outcome the
scientist measures to see whether it responds to the manipulated factor, and here the measured outcome is plant
height. The fertilizer brand, sunlight, and plant variety are either standardized conditions or constants, not
measured responses. OA Tip: a quick check is to phrase the experiment as the effect of X (independent) on Y
(dependent); whatever fills the Y slot is the dependent variable.
WGU C190 Introduction to Biology | OA Study Preparation 2026/2027 2
,Bio WGU Study for OA C190 2026/2027 Complete Questions and Answers (100% Correct)
Q5: A student claims that a new plant food makes ferns grow faster. She treats one fern with the
plant food and measures its growth for two weeks, but she never grows an untreated fern for
comparison. What is the most serious flaw in her investigation?
A. The experiment lasted too long to show any effect
B. Ferns are known not to respond to any plant food
C. She measured growth in centimeters instead of millimeters
D. The investigation lacks a control group for comparison [CORRECT]
Correct Answer: D
Rationale: [Analysis | Competency: Experimental Design] Without an untreated control group, the student
cannot know whether the treated fern grew differently from a normal fern, so any growth she records cannot be
attributed to the plant food. The duration, the unit of measurement, and the biological responsiveness of ferns are
not the central flaw. OA Tip: when an OA design question asks for the most serious flaw, look first for a missing
control group or missing replication, the two most commonly tested weaknesses.
Q6: In a controlled experiment, what is the primary purpose of the control group?
A. To receive every treatment being tested in the experiment
B. To provide a baseline for comparison under normal, untreated conditions [CORRECT]
C. To increase the number of variables operating in the experiment
D. To guarantee that the original hypothesis will be proven true
Correct Answer: B
Rationale: [Recall | Competency: Experimental Design] The control group experiences normal conditions
without the experimental treatment, establishing the baseline against which treated groups are compared. Choice
A describes experimental groups, choice C states the opposite of what controls do, and choice D is impossible
because experiments never guarantee or prove a hypothesis. OA Tip: pair this definition with the fact that
experiments support or fail to support hypotheses but never prove them absolutely.
Q7: In the fertilizer experiment, keeping water, sunlight, soil type, and pot size identical across all
three groups serves what purpose?
A. It guarantees that the fertilized plants will grow taller than the others
B. It eliminates the need to collect or analyze any data
C. It converts the dependent variable into an independent variable
D. It prevents other factors from influencing the measured results [CORRECT]
WGU C190 Introduction to Biology | OA Study Preparation 2026/2027 3
, Bio WGU Study for OA C190 2026/2027 Complete Questions and Answers (100% Correct)
Correct Answer: D
Rationale: [Application | Competency: Experimental Design] Standardized (controlled) variables are held
constant so that fertilizer amount remains the only plausible cause of any difference in plant height. Holding
conditions constant does not guarantee outcomes, remove the need for data, or alter the roles of the variables. OA
Tip: the OA expects you to distinguish three variable types quickly: independent (manipulated), dependent
(measured), and standardized (held constant).
Q8: After measuring 50 plants, a student finds that fertilized plants average 4 cm taller than
unfertilized plants. Which conclusion is scientifically appropriate?
A. Fertilizer causes all plants to grow exactly 4 cm taller
B. The hypothesis is proven true beyond all possible doubt
C. The experiment failed because individual plants grew different amounts
D. The data support the hypothesis, but the effect should be retested [CORRECT]
Correct Answer: D
Rationale: [Analysis | Competency: Data Analysis and Conclusions] Scientific conclusions state that data
support a hypothesis, because natural variation and limited sampling mean results are always provisional and
benefit from replication. The word all overstates the finding, proven is a red-flag word the OA uses to mark
wrong answers, and variation among individuals is normal rather than a failure. OA Tip: treat absolute words
such as prove, all, never, and always as signals of incorrect answer choices on data-interpretation items.
Q9: In a clinical drug trial, neither the participants who receive pills nor the researchers recording
outcomes know who received the real drug and who received a placebo. How does this double-blind
design improve the study?
A. It reduces bias from the expectations of both participants and researchers [CORRECT]
B. It allows the researchers to skip statistical analysis of the results
C. It ensures that every participant receives the active drug
D. It removes the need for any control group in the trial
Correct Answer: A
Rationale: [Application | Competency: Bias Reduction] Blinding prevents the placebo effect in participants and
observer bias in researchers, so measured differences are more attributable to the drug itself. Blinding does not
replace statistics, does not give everyone the drug, and never substitutes for a control group. OA Tip: link design
vocabulary together for the OA: placebo controls expectation, blinding controls bias, and replication controls
random error.
WGU C190 Introduction to Biology | OA Study Preparation 2026/2027 4
