• 50 questions

Biology OSAT Practice Test

Unofficial biology questions for Oklahoma's OSAT Biological Sciences test, field 110, weighted like its three selected-response subareas.

A cut stem is set in water dyed blue, and the dye rises to the leaves. Which tissue carried it?

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Unofficial practice questions, not affiliated with Oklahoma's Office of Educational Quality and Accountability or Pearson. Bank checked October 12, 2026.

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All 50 questions

Subarea I: Cells and organisms 20

  • A cut stem is set in water dyed blue, and the dye rises to the leaves. Which tissue carried it? Wikipedia, Xylem, lead. Written to the OSAT Biological Sciences (110) framework, competency 0004
  • A lake warms far more slowly on a summer day than the sand beside it. What gives water its very high specific heat capacity? Wikipedia, Properties of water, Heat capacity and heats of vaporization and fusion. Written to the OSAT Biological Sciences (110) framework, competency 0001
  • A model of photosynthesis shows ATP and NADPH leaving the light-dependent reactions. Where in the chloroplast are they used next? Wikipedia, Calvin cycle, lead. Written to the OSAT Biological Sciences (110) framework, competency 0003
  • A mutation inactivates a tumor suppressor gene in a cell. What may happen as a result? National Human Genome Research Institute, Talking Glossary: Tumor Suppressor Gene. Written to the OSAT Biological Sciences (110) framework, competency 0002
  • A reaction in a cell runs millions of times faster with its enzyme than without it. How does the enzyme do this? Wikipedia, Enzyme, lead. Written to the OSAT Biological Sciences (110) framework, competency 0001
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Subarea I: Cells and organisms, continued

  • A root hair cell takes in mineral ions that are already more concentrated inside the cell than in the soil water. What does this movement require? Wikipedia, Active transport, lead. Written to the OSAT Biological Sciences (110) framework, competency 0002
  • A seedling on a windowsill bends toward the light. Where does the hormone auxin act to cause the bend? Wikipedia, Phototropism, lead. Written to the OSAT Biological Sciences (110) framework, competency 0004
  • A white blood cell engulfs a bacterium. Which organelle supplies the digestive enzymes that break the bacterium down? National Human Genome Research Institute, Talking Glossary: Lysosome. Written to the OSAT Biological Sciences (110) framework, competency 0002
  • Bacteria at a deep-sea vent build organic matter in total darkness. What is their source of energy? Wikipedia, Chemosynthesis, lead. Written to the OSAT Biological Sciences (110) framework, competency 0003
  • Bacteria have no mitochondria. Where do they carry out the reactions of the citric acid cycle? Wikipedia, Citric acid cycle, lead. Written to the OSAT Biological Sciences (110) framework, competency 0003
  • Body temperature climbs during a run, and sweating brings it back down. In this negative feedback loop, what is the job of the effectors? Wikipedia, Homeostasis, lead. Written to the OSAT Biological Sciences (110) framework, competency 0004
  • In the life cycle of a fern, which phase is diploid and makes spores by meiosis? Wikipedia, Alternation of generations, lead. Written to the OSAT Biological Sciences (110) framework, competency 0004
  • Lactic acid fermentation adds no ATP beyond what glycolysis has made. What, then, does turning pyruvate into lactate do for a cell without oxygen? Wikipedia, Lactic acid fermentation, lead. Written to the OSAT Biological Sciences (110) framework, competency 0003
  • Of the amino acids coded for in proteins, cysteine and methionine contain an element the others lack. Which element? Wikipedia, Sulfur, lead. Written to the OSAT Biological Sciences (110) framework, competency 0001
  • On a hot, dry afternoon the guard cells of a leaf narrow its stomata. What do these pores control? Wikipedia, Stoma, lead. Written to the OSAT Biological Sciences (110) framework, competency 0004
  • One acetyl group enters the citric acid cycle. How many molecules of carbon dioxide does a single turn of the cycle release? Wikipedia, Citric acid cycle, Products. Written to the OSAT Biological Sciences (110) framework, competency 0003
  • Phospholipids make up most of a biological membrane. Which part of each molecule points outward, toward the water on either side? Wikipedia, Phospholipid, lead. Written to the OSAT Biological Sciences (110) framework, competency 0001
  • Stem cells in bone marrow go on dividing through life. What can the cells formed by a dividing stem cell become? National Human Genome Research Institute, Talking Glossary: Stem Cell. Written to the OSAT Biological Sciences (110) framework, competency 0002
  • Two amino acids join to form a dipeptide. What is released as the peptide bond forms? Wikipedia, Peptide bond, Synthesis. Written to the OSAT Biological Sciences (110) framework, competency 0001
  • Why does meiosis have to halve the chromosome number of the cells that become gametes? National Human Genome Research Institute, Talking Glossary: Meiosis. Written to the OSAT Biological Sciences (110) framework, competency 0002

Subarea II: Ecosystems 15

  • A biologist marks 40 fish in a pond and releases them. A week later she nets 50 fish, and 8 of them carry marks. What does the Lincoln–Petersen method estimate for the population? Wikipedia, Mark and recapture, Lincoln–Petersen estimator. Written to the OSAT Biological Sciences (110) framework, competency 0005
  • A country's death rate drops quickly as food supply and sanitation improve, while its birth rate stays high. Which stage of the demographic transition is this, and what happens to its population? Wikipedia, Demographic transition, Overview. Written to the OSAT Biological Sciences (110) framework, competency 0007
  • A fire kills the plants of a hillside and leaves the soil in place. Which process follows, and what speeds it? Wikipedia, Primary succession, lead. Written to the OSAT Biological Sciences (110) framework, competency 0005
  • A remora attaches to a sea turtle and gains transport and food. The turtle is neither helped nor harmed. Which relationship is this? Wikipedia, Commensalism, lead. Written to the OSAT Biological Sciences (110) framework, competency 0005
  • A zoologist removed the few starfish from a stretch of rocky shore and recorded large effects on the other species there. What kind of species were the starfish? Wikipedia, Keystone species, lead and History. Written to the OSAT Biological Sciences (110) framework, competency 0005
  • Along the Great Lakes, river water mixes with lake water in coastal wetlands. No seawater is present. Why does NOAA still describe these as estuaries? NOAA National Ocean Service, What is an estuary?. Written to the OSAT Biological Sciences (110) framework, competency 0005
  • At a sewage treatment plant, what removes the dissolved organic matter during secondary treatment? Wikipedia, Secondary treatment, lead. Written to the OSAT Biological Sciences (110) framework, competency 0007
  • The DDT measured in a lake is lowest in the plankton and highest in the fish-eating birds. What is this rise along a food chain called? Wikipedia, Biomagnification, lead. Written to the OSAT Biological Sciences (110) framework, competency 0007
  • Fertilizer runoff loads an estuary with nutrients. By NOAA's account of eutrophication, what follows? NOAA National Ocean Service, What is eutrophication?. Written to the OSAT Biological Sciences (110) framework, competency 0007
  • How does the phosphorus cycle differ from the carbon, nitrogen and water cycles? Wikipedia, Phosphorus cycle, lead. Written to the OSAT Biological Sciences (110) framework, competency 0006
  • In parts of the ocean the consumers outweigh the producers they feed on, so one pyramid model stands upside down. Which pyramid can never be inverted? Wikipedia, Ecological pyramid, lead and Pyramid of energy. Written to the OSAT Biological Sciences (110) framework, competency 0006
  • In waterlogged soil, bacteria use nitrate in place of oxygen. What does denitrification finally produce? Wikipedia, Denitrification, lead. Written to the OSAT Biological Sciences (110) framework, competency 0006
  • The phytoplankton of a lake store 200,000 kilocalories. By the ten percent law, about how much is stored three trophic levels up, in the large fish? Wikipedia, Ecological efficiency, Ten percent law. Written to the OSAT Biological Sciences (110) framework, competency 0006
  • Rhizobia in the root nodules of a soybean plant carry out nitrogen fixation. What does that process do? Wikipedia, Nitrogen fixation, lead. Written to the OSAT Biological Sciences (110) framework, competency 0006
  • Which human activity does NOAA name as a way invasive species are carried into new coastal waters? NOAA National Ocean Service, What is an invasive species?. Written to the OSAT Biological Sciences (110) framework, competency 0007

Subarea III: Heredity and evolution 15

  • A black guinea pig could be homozygous dominant or heterozygous. It is bred with a homozygous recessive white one, and some of the offspring are white. What does the test cross show? Wikipedia, Test cross, lead. Written to the OSAT Biological Sciences (110) framework, competency 0009
  • A canyon forms and splits a squirrel population in two, cutting off gene flow. Over time the two groups become separate species. Which mode of speciation is this? Wikipedia, Allopatric speciation, lead. Written to the OSAT Biological Sciences (110) framework, competency 0010
  • A codon on a messenger RNA reads GCA. Which anticodon on a transfer RNA pairs with it? National Human Genome Research Institute, Talking Glossary: Anticodon. Written to the OSAT Biological Sciences (110) framework, competency 0008
  • A field of wildflowers is in Hardy–Weinberg equilibrium, and 4 plants in every 100 have the recessive white flowers. What share of the plants carry one white allele and one purple allele? Wikipedia, Hardy–Weinberg principle, lead. Written to the OSAT Biological Sciences (110) framework, competency 0010
  • A fossil species shows little change for most of its history, and new species appear in rare, geologically rapid events of branching. Which theory proposes this pattern? Wikipedia, Punctuated equilibrium, lead. Written to the OSAT Biological Sciences (110) framework, competency 0010
  • A laboratory image shows the chromosomes of one human cell arranged in numerical order: 22 pairs of autosomes and a pair of sex chromosomes. What is the image, and what is it used to look for? National Human Genome Research Institute, Talking Glossary: Karyotype. Written to the OSAT Biological Sciences (110) framework, competency 0009
  • A student has separated DNA fragments by electrophoresis and wants to know their sizes. What must have been run on the same gel? National Human Genome Research Institute, Talking Glossary: Electrophoresis. Written to the OSAT Biological Sciences (110) framework, competency 0008
  • A trait is caused by a gene on the circular chromosome inside the mitochondria. From whom do offspring inherit it? National Human Genome Research Institute, Talking Glossary: Mitochondrial DNA. Written to the OSAT Biological Sciences (110) framework, competency 0009
  • After one round of DNA replication, what does each daughter double helix contain? Wikipedia, Semiconservative replication, lead. Written to the OSAT Biological Sciences (110) framework, competency 0008
  • By chance alone, an allele disappears from a herd of 20 deer within a few generations. Which mechanism of evolution is this, and where does it act most strongly? National Human Genome Research Institute, Talking Glossary: Genetic Drift. Written to the OSAT Biological Sciences (110) framework, competency 0010
  • Cystic fibrosis is inherited as an autosomal recessive trait. Two parents each carry one mutated copy of the CFTR gene and one working copy. What is the chance that a child of theirs is affected? National Human Genome Research Institute, Talking Glossary: Cystic Fibrosis. Written to the OSAT Biological Sciences (110) framework, competency 0009
  • On a cladogram, what makes a group of organisms a clade? Wikipedia, Clade, lead. Written to the OSAT Biological Sciences (110) framework, competency 0010
  • The regulation of the lac operon is called negative inducible. What does that mean? Wikipedia, Lac operon, lead. Written to the OSAT Biological Sciences (110) framework, competency 0008
  • To have bacteria copy a human gene, scientists splice the gene into a small circular DNA molecule that replicates apart from the chromosome. What is that molecule? National Human Genome Research Institute, Talking Glossary: Plasmid. Written to the OSAT Biological Sciences (110) framework, competency 0008
  • Two pea plants, each heterozygous for seed shape and for seed color, are crossed. The two genes assort independently. Which ratio of phenotypes did Mendel find in such crosses? Wikipedia, Mendelian inheritance, Law of independent assortment. Written to the OSAT Biological Sciences (110) framework, competency 0009

How this list was compiled: Our own questions, written to the test design and framework of Oklahoma Subject Area Tests field 110, Biological Sciences, in the study guide on the Certification Examinations for Oklahoma Educators website (https://www.ceoe.nesinc.com/Content/StudyGuide/OK_SG_OBJ_110.htm, copyright 2023 Office of Educational Quality and Accountability and Pearson Education, Inc.; test page https://www.ceoe.nesinc.com/TestView.aspx?f=HTML_FRAG/OK110_TestPage.html, read 2026-10-12): 80 selected-response questions and 1 constructed-response assignment in 4 hours, passing score 240; selected response weighs Structures and Processes of Cells and Organisms (competencies 0001 to 0004) 33%, Ecosystem Energy Flow, Interactions, and Dynamics (0005 to 0007) 26% and Heredity and Evolution (0008 to 0010) 26%, and the constructed response (0011) 15%. The bank holds 50, five for each of the ten selected-response competencies. Every fact was read on the public page named under its question: the Talking Glossary of the National Human Genome Research Institute, NOAA's National Ocean Service and the named Wikipedia articles. Licence: Questions, choices and explanations are original work of this site.

How it works

This Biology OSAT practice test is free, unofficial and not affiliated with Oklahoma's Office of Educational Quality and Accountability or Pearson. Its 50 questions of our own follow the ten selected-response competencies of Biological Sciences, field 110, five apiece.

Read the full guide

OSAT Biological Sciences (110): the three selected-response subareas

The framework on the CEOE site, read October 12, 2026, gives three selected-response subareas: Structures and Processes of Cells and Organisms at 33% of the test, Ecosystem Energy Flow, Interactions, and Dynamics at 26%, and Heredity and Evolution at 26%. Our 50 questions split 20, 15 and 15 among them.

The written assignment

The other 15% is one constructed-response assignment: analyze a lesson plan and a student work sample for a science standard, then describe differentiated instruction. Nothing here practices it, and the exam on this page, 40 questions, has no clock because the real 4 hours also cover that writing.

  • Each selected-response competency ends with two descriptors on the Oklahoma Academic Standards for Science: its science and engineering practices and its crosscutting concepts.

Questions and answers

Is this Biology OSAT practice test free?

Yes, and nothing asks you to sign up. No question is taken from the real test, its sample questions or its official practice test.

How many questions are on the OSAT Biological Sciences (110) test?

The test page gives 80 selected-response questions plus one constructed-response assignment. A test center allows 4 hours of testing and an online proctor 3 hours, with a 15-minute tutorial before either.

What is the passing score for OSAT Biological Sciences?

The test page gives 240. Because the written assignment counts toward it, a number right on these questions cannot be turned into a scaled score, and no pass verdict is shown here.

What is on the OSAT biology test?

Biochemistry, cells, photosynthesis and respiration, and how organisms grow and reproduce; then biomes, the flow of matter and energy, and human impact; then molecular genetics, inheritance and evolution. The test page lists no reference materials, so no formula sheet is given.

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