200+ Free Praxis Biology 5236 Practice Questions

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A student sets up an experiment testing whether light intensity affects algae growth rate. She uses three tanks: one in bright light, one in dim light, and one covered in foil. Which tank is the control group?

The bright-light tank, because it represents the ideal growth condition

The dim-light tank, because it is in the middle of the range tested

The foil-covered tank with no light, because it establishes baseline growth without the tested variable

All three tanks equally serve as controls for each other

to track

2026 Statistics

Key Facts: Praxis Biology 5236 Exam

150

Selected-Response Questions

ETS Praxis 5236 Study Companion

2h 30m

Testing Time

ETS Praxis 5236 Study Companion

$130

Current Fee

ETS Praxis Website

26%

Largest Domain (Genetics/Evolution)

ETS Praxis 5236 Study Companion

For 2026 planning, ETS still lists Praxis 5236 as a 150-question, 2.5-hour computer-delivered selected-response subject assessment priced at $130. The official study companion weights the exam 13% Nature and Impact of Science, 22% Cell Biology, 26% Genetics and Evolution, 20% Diversity of Life, and 19% Ecology.

Sample Praxis Biology 5236 Practice Questions

Try these sample questions to test your Praxis Biology 5236 exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 200+ question experience with AI tutoring.

1A student sets up an experiment testing whether light intensity affects algae growth rate. She uses three tanks: one in bright light, one in dim light, and one covered in foil. Which tank is the control group?

A.The bright-light tank, because it represents the ideal growth condition

B.The dim-light tank, because it is in the middle of the range tested

C.The foil-covered tank with no light, because it establishes baseline growth without the tested variable

D.All three tanks equally serve as controls for each other

Explanation: The control group receives no treatment of the independent variable so that it establishes a baseline. In a light-intensity experiment, the tank with no light (foil-covered) removes the variable being tested and shows what growth occurs without any experimental light manipulation. The bright- and dim-light tanks are both experimental groups at different treatment levels.

2A researcher measures blood pressure in 500 patients over one year and finds that those who exercise more have lower blood pressure. She concludes that exercise lowers blood pressure. What is the main limitation of this conclusion?

A.The sample size of 500 is too small to draw any conclusion

B.Correlation between exercise and blood pressure does not establish that exercise causes lower blood pressure

C.Blood pressure cannot be measured accurately outside of a clinical trial

D.The study lasted only one year, making all findings invalid

Explanation: This is an observational study demonstrating a correlation between two variables. Correlation does not establish causation; a confounding variable (e.g., diet, genetics, stress) might cause both higher exercise rates and lower blood pressure. Only a randomized controlled trial can provide evidence of a causal relationship.

3A biology textbook states that 'cells arise only from pre-existing cells.' This statement is best classified as which type of scientific knowledge?

A.A hypothesis, because it has not been tested experimentally

B.A theory, because it is a well-tested, broad explanation of a natural phenomenon

C.A law, because it describes an observed phenomenon without explaining why

D.An inference, because it was derived from indirect observations

Explanation: Cell theory — which includes the principle that cells arise from pre-existing cells — is a scientific theory: a broad, well-supported explanation of a natural phenomenon backed by extensive evidence from Virchow, Pasteur, Schleiden, and Schwann. Theories in science explain mechanisms and are supported by overwhelming evidence.

4Scientists conduct the same experiment multiple times and get similar results. Another research group then performs the same experiment independently and gets the same result. Which scientific principle does this best demonstrate?

A.Parsimony — choosing the simplest explanation

B.Falsifiability — the experiment can be disproven

C.Reproducibility — independent replication confirms reliability of findings

D.Peer review — experts evaluate research before publication

Explanation: Reproducibility means that independent researchers using the same methods can obtain the same results, which strengthens confidence in the finding. It distinguishes genuine phenomena from artifacts of a specific lab, instrument, or experimenter and is a cornerstone of scientific validity.

5A student measures enzyme activity (in units per minute) at five temperatures and creates a graph. The curve rises steeply, peaks at 37°C, then drops sharply at higher temperatures. The drop above 37°C is most likely due to:

A.Substrate depletion as the reaction proceeds too quickly

B.Enzyme denaturation causing the active site shape to change permanently

C.The reaction reaching chemical equilibrium at high temperatures

D.CO₂ production inhibiting the enzyme's active site

Explanation: At temperatures above the enzyme's optimum, excess thermal energy disrupts the hydrogen bonds and hydrophobic interactions that maintain the three-dimensional shape of the protein. This denaturation alters the active site geometry, preventing proper substrate binding and sharply reducing activity — often irreversibly.

6A study reports that eating dark chocolate is associated with reduced cardiovascular disease risk (p = 0.03). What does p = 0.03 mean in the context of this study?

A.There is a 3% chance that dark chocolate prevents cardiovascular disease

B.There is a 3% probability that the observed association occurred by chance if there were truly no effect

C.The study has 97% statistical power to detect a true effect

D.Dark chocolate reduces cardiovascular disease risk by 3%

Explanation: The p-value represents the probability of obtaining results at least as extreme as those observed, assuming the null hypothesis (no association) is true. A p-value of 0.03 means there is a 3% chance the observed association arose by random chance — below the conventional significance threshold of 0.05, suggesting the result is statistically significant.

7A researcher graphs photosynthesis rate (y-axis) vs. CO₂ concentration (x-axis). The line rises steeply at first, then levels off into a plateau. A second line, measured at higher light intensity, reaches the same plateau but more slowly. What does this graph demonstrate?

A.CO₂ concentration alone determines photosynthesis rate regardless of light

B.At the plateau, CO₂ is no longer needed for photosynthesis

C.At the plateau, light intensity has become the limiting factor

D.Higher CO₂ always produces a higher photosynthesis rate

Explanation: When photosynthesis rate plateaus despite increasing CO₂, the reaction has reached its maximum rate under current conditions. At this point, the system is saturated with CO₂ and another factor — here, light intensity — has become limiting. The higher-light-intensity line demonstrates that, with more light energy, the same CO₂ plateau can be reached but at a different rate, confirming that light is the limiting factor at the plateau.

8A double-blind randomized controlled trial (RCT) is considered the gold standard for evaluating the effectiveness of a new drug because it:

A.Uses the largest possible sample size

B.Eliminates both placebo effects and observer bias through blinding and random assignment

C.Ensures that all participants receive the experimental treatment

D.Guarantees that no side effects will occur during the trial

Explanation: Double-blind RCTs control for placebo effects (blinding participants) and observer bias (blinding researchers), while randomization distributes confounding variables equally across groups. This combination allows researchers to attribute differences in outcomes specifically to the drug, making it the most rigorous design for evaluating treatment efficacy.

9What is the primary purpose of peer review in the scientific publication process?

A.To guarantee that published findings are always correct and free of error

B.To have qualified experts evaluate methods, analysis, and conclusions for soundness before publication

C.To replace the need for independent replication of experimental results

D.To ensure that only revolutionary findings are published in major journals

Explanation: Peer review is a quality-control mechanism in which independent experts scrutinize a manuscript's methodology, statistical analysis, and conclusions for errors or unsupported claims before publication. It improves research quality but does not guarantee correctness — errors and even fraud sometimes pass review, which is why independent replication remains essential.

10A student measures the heights of 30 bean seedlings grown under identical conditions. The mean height is 12 cm with a standard deviation of 2 cm. According to the empirical rule for a normal distribution, approximately what percentage of seedlings would be expected to fall between 10 cm and 14 cm?

A.50%

B.68%

C.95%

D.99.7%

Explanation: The range 10–14 cm spans exactly one standard deviation (2 cm) above and below the mean of 12 cm. The empirical (68-95-99.7) rule states that approximately 68% of data in a normal distribution fall within ±1 standard deviation of the mean. So about 68% of seedlings would be expected between 10 and 14 cm.

About the Praxis Biology 5236 Exam

Praxis Biology Content Knowledge (5236) is the ETS subject assessment for secondary biology teacher certification. This practice bank covers all five official domains: Nature of Science, Cell Biology, Genetics and Evolution, Diversity of Life and Organismal Biology, and Ecology.

Questions

150 scored questions

Time Limit

2 hours 30 minutes

Passing Score

Varies by state

Exam Fee

$130 (ETS / Praxis)

Praxis Biology 5236 Exam Content Outline

13%

Nature and Impact of Science and Engineering

Scientific inquiry, methodology, data analysis, lab safety, and the societal role of science and technology.

22%

Cell Biology: Cell Structure and Function

Cell organelles, membrane transport, cellular processes like photosynthesis and respiration, and the cell cycle.

26%

Genetics and Evolution

Molecular genetics (DNA, RNA, protein synthesis), heredity, meiosis, and the principles and evidence of evolution.

20%

Diversity of Life and Organismal Biology

Taxonomy, classification, characteristics of kingdoms, and the structure and function of major plant and animal systems.

19%

Ecology: Organisms and Environments

Ecological principles, populations, communities, ecosystems, biomes, biogeochemical cycles, and environmental issues.

How to Pass the Praxis Biology 5236 Exam

What You Need to Know

Passing score: Varies by state
Exam length: 150 questions
Time limit: 2 hours 30 minutes
Exam fee: $130

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

Praxis Biology 5236 Study Tips from Top Performers

1Focus on the major concepts within each domain, as the exam tests a broad range of knowledge.

2Review fundamental biological processes like photosynthesis, cellular respiration, and protein synthesis in detail.

3Practice interpreting data from graphs and tables, as data analysis skills are tested.

4Understand the principles of evolution and be able to apply them to different scenarios.

5For ecology, be familiar with the major biomes and biogeochemical cycles.

Frequently Asked Questions

How many questions are on the Praxis Biology exam (5236)?

The Praxis Biology Content Knowledge exam has 150 selected-response questions.

How long is the Praxis Biology exam?

The testing time is 2 hours and 30 minutes.

What is a passing score on the Praxis Biology exam?

Passing scores for the Praxis Biology exam are set by each state, so they vary. You should check the requirements for the specific state in which you are seeking licensure.

What content is covered on the Praxis Biology exam?

The exam covers five main content areas: Nature of Science, Cell Biology, Genetics and Evolution, Diversity of Life and Organismal Biology, and Ecology.