ILTS Science: Biology (239) study guide
ILTS Science: Biology (239) · Work through your exam, one topic at a time.
Science: Biology (239) is one of the content-area tests listed in the Illinois Licensure Testing System (ILTS) catalog, published on the ILTS site at il.nesinc.com. It sits alongside Science: Chemistry (240), Science: Earth and Space Science (241), Science: Environmental Science (242), and Science: Physics (243) as a single-subject science assessment, and it is intended for candidates seeking an Illinois educator license with a biology endorsement. The ILTS program is administered for the Illinois State Board of Education, but this page is independent study material and is not affiliated with ILTS, Pearson, or the State of Illinois. The public catalog does not publish a subdomain breakdown, item count, or time limit for this title, so build your preparation around the biology content that a secondary biology teacher is expected to teach: molecules and cells, genetics and evolution, organisms and populations, and the nature and practice of scientific inquiry, including data analysis and experimental design. Start by confirming the current test requirements and available preparation materials through the official ILTS website. Then work through practice questions under timed conditions, review every miss down to the underlying concept, and revisit the topics you cannot explain aloud. Topics on this exam: Biology content domain (official subdomain breakdown not published in source). The ILTS Science: Biology (239) study guide has 1 section and about 425 words.
01Biology Content Domain
The ILTS Science: Biology (239) biology content domain samples the breadth of introductory college biology: molecular and cellular biology, genetics and inheritance, evolution and diversity, organismal physiology, and ecology. Because the state does not publish a subdomain breakdown, build fluency across those connected scales rather than memorizing isolated facts; questions often ask you to predict an outcome from a mechanism. Structure determines function from macromolecules upward: phospholipid amphipathy creates bilayers, protein tertiary structure creates active sites, and surface-area-to-volume limits constrain cell size. Energy flows through coupled redox reactions.
425 words, about 2 minMore study resources for ILTS Science: Biology (239)
- Practice questionsA student examines a cell and observes a rigid cell wall, a large central vacuole, and numerous chloroplasts.
- FlashcardsCell membrane structure. A phospholipid bilayer with hydrophilic heads facing aqueous environments and hydrophobic tails inward, studded with proteins and cholesterol; it is selectively permeable and described by the fluid mosaic model.
- Cheat sheetMacromolecule building blocks: carbohydrates from monosaccharides joined by glycosidic bonds; proteins from amino acids joined by peptide bonds; nucleic acids from nucleotides joined by phosphodiester bonds; lipids assembled from glycerol plus fatty acids (triglycerides) or isoprenoid units (steroids).
- Key termsCell membrane. A thin, flexible barrier of phospholipids and proteins surrounding every cell that controls which substances enter and leave, and helps cells communicate and stick to neighbors.
- Study planMap the full ILTS 239 content outline into a personal checklist of every biology subarea, marking each as strong, shaky, or unknown before studying anything.
- Common mistakesThe candidate learned monohybrid crosses visually but never internalized that multi-child or multi-gene problems require the binomial expansion or the multiplication rule applied to unordered outcomes; under time pressure they default to the single-square answer.
- Exam-day guideBring the original, unexpired ID (driver's license or passport) whose name matches your registration exactly.