OAT section study center
OAT Natural Sciences: connect Biology with both Chemistry sections.
The OAT Survey of the Natural Sciences contains 100 items in 90 minutes: Biology (40), General Chemistry (30), and Organic Chemistry (30). Rotate among all three subjects and use the Organic Chemistry outline implemented in June 2026.
Understand the section
What to review for Survey of the Natural Sciences
The OAT Survey of the Natural Sciences contains 100 items in 90 minutes: Biology (40), General Chemistry (30), and Organic Chemistry (30). Rotate among all three subjects and use the Organic Chemistry outline implemented in June 2026.
Biology
40 items
The official domains include Cell and Molecular Biology, Diversity of Life, Structure and Function of Systems, Genetics, and Evolution and Ecology.
General Chemistry
30 items
Review stoichiometry, gases, liquids and solids, solutions, acids and bases, equilibria, thermodynamics, kinetics, redox, atomic and molecular structure, and periodic properties.
Organic Chemistry
30 items
The implemented Organic Chemistry outline groups topics into mechanisms, chemical synthesis, acid-base chemistry, chemical and physical properties of molecules, and structural evaluation. Subtopics include curved-arrow and reaction-coordinate work; one-, two-, and multi-step synthesis; acidity/basicity; lab techniques and spectroscopy; and nomenclature, stereochemistry, and structure/bonding.
Balanced science rotation
Three scored disciplines
Rotate among Biology, General Chemistry, and Organic Chemistry. Record accuracy and confidence separately so a strong subject does not hide a weaker one.
Use the official content outline as the boundary for review. The section counts and times here come from the 2026 OAT Candidate Guide and User Guide; verify the current guide before your test date.
A practical study route
Turn the outline into focused practice
- Take a balanced baseline. Use separate short sets for Biology, General Chemistry, and Organic Chemistry and note content and reasoning misses.
- Build recall for Biology. Review cell processes, organismal diversity, body systems, genetics, evolution, and ecology with active recall.
- Practice Chemistry problem types. Rotate quantitative General Chemistry with Organic Chemistry structure, reactions, and spectroscopy.
- Use the implemented Organic Chemistry outline. The Department of Testing Services’ September 23, 2026 bulletin confirms the new specifications took effect in June 2026. The OAT homepage and Candidate Guide still contain earlier anticipated wording; follow the applicable test-date guide and the implemented outline.
- Use section timing. Practice mixed science sets with the 90-minute section limit in mind, then review each missed concept.
Official information and study tools
Choose reliable Survey of the Natural Sciences resources
Start with official specifications and official practice modules. Commercial resources can supplement review; the OAT Program advises candidates to confirm outside materials reflect current test content.
- 2026 OAT Candidate Guide — official section count, timing, overall rules, and current exam outline.
- 2026 OAT User Guide — official detailed test specifications for this section.
- Official OAT practice tests and modules — practice modules written by OAT test constructors.
- Mometrix OAT practice review — independent practice resource; compare lessons to the official specifications.
- OAT flashcards — independent recall practice.
The OAT Program states that it does not endorse preparation courses. Linked commercial resources are independent study aids.
Quick answers
Survey of the Natural Sciences questions, answered
How many items are in the OAT Survey of the Natural Sciences?
The 2026 Candidate Guide lists 100 items in 90 minutes: 40 Biology, 30 General Chemistry, and 30 Organic Chemistry.
Does Natural Sciences include Physics?
No. Physics is a separate 40-item OAT test section.
Which Organic Chemistry outline should I use?
The Department of Testing Services’ September 23, 2026 bulletin confirms the updated outline took effect in June 2026. The OAT homepage and 2026 Candidate Guide retain earlier anticipated wording and both outlines; use the implemented outline and confirm your test-date guide.
How should I split study time?
Start with a baseline by discipline and allocate more review to repeated gaps while continuing to revisit all three subjects.
Check the source
Official source and update note
This independent Natural Sciences center reflects the Organic Chemistry outline implemented in June 2026. Check the official update bulletin and the candidate guide that applies to your test date.
- 2026 OAT Candidate Guide — official section count, timing, overall rules, and current exam outline.
- 2026 OAT User Guide — official detailed test specifications for this section.
- Official OAT practice tests and modules — practice modules written by OAT test constructors.
- Mometrix OAT practice review — independent practice resource; compare lessons to the official specifications.
- OAT flashcards — independent recall practice.
- ADA examination update bulletin (updated September 23, 2026) — confirms the June 2026 Organic Chemistry implementation date.
Reviewed October 2026. This independent educational resource is not affiliated with or endorsed by the Optometry Admission Test Program, ADA, or ASCO.