TEAS biology: the 5 topics, with tables and practice
Biology is 9 of the 44 scored questions on TEAS science. ATI's Version 7 outline names five topics: cell structure and function, how DNA builds proteins, Mendel's laws of inheritance, the four macromolecules, and the role of microorganisms in disease. Each is below with the facts the questions use, study tables, worked Punnett squares, 10 practice questions and a 10-day plan.
It is introductory biology, the level of a high-school or first college course. The questions ask you to recognise a structure, compare two processes, or predict an offspring ratio, not to recall rare names.
How many biology questions are on the TEAS?
| Science content area | Scored questions |
|---|---|
| Human anatomy and physiology | 18 |
| Biology | 9 |
| Scientific reasoning | 9 |
| Chemistry | 8 |
| Total | 44 scored + 6 unscored = 50, in 60 minutes |
Counts are ATI's for the TEAS Version 7, the current exam (what is on the TEAS test has the whole exam). Biology is about 20% of scored science. It also sits under other questions: cells and transport in anatomy and physiology, enzymes and pH in chemistry. For the order to study all four areas, read how to study for the TEAS science section.
The five biology topics on the TEAS
| ATI topic | What the questions ask |
|---|---|
| Cell structure, function and organization | Prokaryotic vs eukaryotic cells, organelles and their jobs, membrane transport, mitosis and meiosis, levels of organization |
| Genetic material and protein structure | DNA and RNA, base pairing, replication, transcription, translation, codons, mutations |
| Mendel's laws of inheritance | Dominant and recessive, genotype and phenotype, Punnett squares, other inheritance patterns |
| Macromolecules | Carbohydrates, lipids, proteins, nucleic acids: building blocks and jobs; enzymes |
| Microorganisms in disease | Bacteria, viruses, fungi and protozoa; how they cause disease; what treats each |
Topic names follow ATI's Version 7 content outline. ATI doesn't say how many questions each gets; with 9 questions and 5 topics, plan on one or two each, with cells usually the biggest share because mitosis and transport sit under it.
Cell structure and function
All living things are made of cells. The first split the TEAS asks about is prokaryotic vs eukaryotic.
| Prokaryotic cell | Eukaryotic cell | |
|---|---|---|
| Examples | Bacteria, archaea | Animals, plants, fungi, protists |
| Nucleus | No; DNA in a nucleoid region | Yes, inside a nuclear envelope |
| Membrane-bound organelles | No | Yes (mitochondria, ER, Golgi…) |
| Ribosomes | Yes, smaller | Yes, larger |
| Size | About 0.1–5 micrometers | About 10–100 micrometers |
| Cell wall | Most have one | Plants (cellulose) and fungi (chitin); animal cells don't |
The organelles and their jobs
| Organelle | Job | Remember it as |
|---|---|---|
| Nucleus | Holds DNA; controls the cell | The control center |
| Ribosome | Builds proteins from amino acids | The protein factory |
| Rough ER | Ribosome-studded; folds and ships proteins | Rough = ribosomes |
| Smooth ER | Makes lipids; detoxifies | Smooth = lipids |
| Golgi apparatus | Modifies, sorts and packages proteins | The post office |
| Mitochondrion | Cellular respiration: makes ATP | The power plant |
| Lysosome | Breaks down waste with enzymes | The recycling bin |
| Cell membrane | Controls what enters and leaves | The gate |
| Chloroplast (plants) | Photosynthesis | Solar panel |
| Cell wall (plants, fungi, bacteria) | Support and shape | The outer wall |
| Central vacuole (plants) | Stores water; keeps the cell firm | The water tank |
Plant cells have three things animal cells don't: a cell wall, chloroplasts and a large central vacuole. Questions often ask which structure a plant cell has that an animal cell lacks.
Levels of organization
From small to large: cell → tissue (similar cells working together) → organ (tissues forming a structure with a job) → organ system → organism. A stomach is an organ; the digestive system is an organ system. The TEAS anatomy and physiology guide takes it from there.
Moving things across the membrane
| Process | Direction | Needs energy (ATP)? | Example |
|---|---|---|---|
| Diffusion | High to low concentration | No | Oxygen into a cell |
| Facilitated diffusion | High to low, through a protein channel | No | Glucose into many cells |
| Osmosis | Water toward the side with more solute | No | Water into a cell in pure water |
| Active transport | Low to high, against the gradient | Yes | The sodium-potassium pump |
| Endocytosis / exocytosis | Large particles in / out in vesicles | Yes | A white blood cell taking in bacteria |
Hypertonic, hypotonic and isotonic solutions are in the TEAS chemistry guide's solutions section.
Mitosis and meiosis
| Mitosis | Meiosis | |
|---|---|---|
| Purpose | Growth, repair, replacing cells | Making gametes (egg and sperm) |
| Divisions | One | Two (meiosis I and II) |
| Cells made | 2 | 4 |
| Chromosomes in each (humans) | 46 (diploid, 2n) | 23 (haploid, n) |
| Same as the parent cell? | Yes, identical | No, genetically different |
| Crossing over | No | Yes, in prophase I |
The phases of mitosis, in order: prophase (chromosomes condense, the nuclear envelope breaks down), metaphase (chromosomes line up in the middle), anaphase (sister chromatids pull apart), telophase (two nuclei form). Cytokinesis then splits the cytoplasm. "PMAT" holds the order; interphase, when DNA is copied, comes before them. A question that says "chromosomes line up at the cell's equator" is metaphase; "pulled to opposite poles" is anaphase.
DNA, RNA and protein synthesis
The outline's second topic is how genetic material sets the structure of proteins. The chain: DNA → (transcription) → mRNA → (translation) → protein.
| DNA | RNA | |
|---|---|---|
| Sugar | Deoxyribose | Ribose |
| Strands | Two (double helix) | One |
| Bases | A, T, C, G | A, U, C, G (uracil replaces thymine) |
| Pairing | A–T, C–G | A–U, C–G |
| Where (eukaryotes) | Mostly the nucleus | Made in the nucleus, works in the cytoplasm |
| Job | Stores the genetic code | mRNA carries it; tRNA brings amino acids; rRNA forms ribosomes |
Step by step
- Replication (before a cell divides): DNA unzips and each strand is a template for a new one, so each copy keeps one old and one new strand (semi-conservative).
- Transcription (nucleus): a gene's DNA is read into mRNA. DNA template TAC GGA becomes mRNA AUG CCU.
- Translation (ribosome): the ribosome reads mRNA three bases at a time. Each three-base codon stands for one amino acid; tRNA carries the matching amino acid in. AUG is the start codon (methionine); UAA, UAG and UGA are stop codons.
- Folding: the amino acid chain folds into the protein's shape, and the shape sets its job.
Worked example: a stretch of mRNA codes for 50 amino acids. How many bases is that, not counting the stop codon? 50 × 3 = 150 bases.
Mutations: a substitution swaps one base and may change one amino acid (sickle cell disease is a single substitution in a hemoglobin gene). An insertion or deletion of one base shifts every codon after it (a frameshift), which usually changes the protein much more.
Mendel's laws and Punnett squares
| Word | Meaning | Example |
|---|---|---|
| Allele | A version of a gene | B (brown) or b (blue) |
| Dominant / recessive | Dominant shows with one copy; recessive only with two | Bb shows brown |
| Genotype / phenotype | The alleles / the trait you see | Bb / brown eyes |
| Homozygous / heterozygous | Two same alleles / two different | BB or bb / Bb |
| Law of segregation | Each parent passes one of its two alleles | Bb parent gives B or b |
| Law of independent assortment | Genes on different chromosomes are passed separately | Eye color doesn't decide height |
Worked Punnett square 1: two heterozygous parents
Brown (B) is dominant over blue (b). Both parents are Bb. What share of children would have blue eyes?
| B | b | |
|---|---|---|
| B | BB | Bb |
| b | Bb | bb |
Answer: 1 of 4 boxes is bb: 25% blue. Genotypes come out 1 BB : 2 Bb : 1 bb; phenotypes 3 brown : 1 blue. A question asking for the share of carriers (Bb) wants 50%.
Worked Punnett square 2: blood type, codominance
ABO blood type has three alleles: IA and IB are codominant, i (O) is recessive. A type A parent (IAi) and a type B parent (IBi) have a child. What types are possible?
| IB | i | |
|---|---|---|
| IA | IAIB (AB) | IAi (A) |
| i | IBi (B) | ii (O) |
Answer: all four, 25% each: AB, A, B and O. Codominance means both show (AB). Incomplete dominance is different: a blend, such as red × white flowers giving pink.
Worked Punnett square 3: X-linked
A mother carries a recessive X-linked allele (XHXh); the father is unaffected (XHY). What share of sons are affected?
Answer: sons get Y from the father and either XH or Xh from the mother, so 50% of sons are affected; daughters are unaffected, half of them carriers. That is why X-linked recessive conditions such as hemophilia show up more in males.
The four macromolecules
| Macromolecule | Building block (monomer) | Elements | Jobs | Examples |
|---|---|---|---|---|
| Carbohydrates | Monosaccharides (glucose) | C, H, O | Quick energy; plant structure | Glucose, starch, glycogen, cellulose |
| Lipids | Glycerol and fatty acids (no true monomer) | C, H, O (phospholipids add P) | Long-term energy, cell membranes, hormones, insulation | Fats, oils, phospholipids, steroids such as cholesterol |
| Proteins | Amino acids (20 kinds) | C, H, O, N (often S) | Enzymes, structure, transport, antibodies, signals | Hemoglobin, collagen, insulin, amylase |
| Nucleic acids | Nucleotides | C, H, O, N, P | Store and carry genetic information | DNA, RNA (ATP is a nucleotide too) |
Two ideas tie this table together. Monomers join by dehydration synthesis (a water molecule removed) and come apart by hydrolysis (water added); digestion is hydrolysis. And enzymes are proteins that speed up reactions by lowering activation energy; heat or the wrong pH changes their shape (denatures them) and stops them working. Enzyme names usually end in "-ase": lactase breaks down lactose.
A fast way to answer "which macromolecule": nitrogen points to protein or nucleic acid; phosphorus to nucleic acid or phospholipid; a "-ose" ending to a carbohydrate; "does not dissolve in water" to a lipid.
Microorganisms and disease
| Microorganism | Cell type | Treated with | Diseases (examples) |
|---|---|---|---|
| Bacteria | Prokaryotic, single cell | Antibiotics | Strep throat, tuberculosis, many urinary tract infections |
| Viruses | Not cells: genetic material in a protein coat; reproduce only inside a host cell | Antivirals for some; vaccines prevent many. Antibiotics don't work | Influenza, measles, HIV, the common cold, COVID-19 |
| Fungi | Eukaryotic; yeasts and molds | Antifungals | Athlete's foot, ringworm, yeast infections |
| Protozoa | Eukaryotic, single cell | Antiparasitic drugs | Malaria, giardiasis |
Questions also ask how disease spreads (direct contact, droplets and air, contaminated food or water, and vectors such as mosquitoes) and how the body fights back: the skin and mucus as barriers, white blood cells, and antibodies from the immune system. Not all microbes harm us: gut bacteria help digestion and make vitamin K. A pathogen is a microbe that causes disease.
The most-tested point: antibiotics kill bacteria, not viruses. A question about flu treated with antibiotics is testing exactly that.
To see how biology sits next to your other sections, take our free TEAS practice test: 15 questions across all four sections, scored against your program's minimum, with the reason for every answer.
10 TEAS biology practice questions
Our own questions, in the style of the topics above. Cover the answers and give yourself 72 seconds each, the section's pace.
- Which organelle makes most of a cell's ATP?
Answer: the mitochondrion. - Which has no nucleus: (a) a liver cell (b) a yeast cell (c) a bacterium (d) a leaf cell?
Answer: (c). Bacteria are prokaryotes. - Which structure does a plant cell have that an animal cell lacks? (a) ribosome (b) cell membrane (c) cell wall (d) mitochondrion
Answer: (c). - A DNA template strand reads TAC CGT. What mRNA is made from it?
Answer: AUG GCA. A pairs with U in RNA. - How many cells, and how many chromosomes each, does meiosis make from one human cell?
Answer: 4 cells, 23 chromosomes each. - Tall (T) is dominant. A Tt plant is crossed with a tt plant. What share of offspring are short?
Answer: 50%. Half the boxes are tt. - What is the monomer of a protein?
Answer: an amino acid. - Which macromolecule forms most of the cell membrane?
Answer: lipids (phospholipids). - Which infection would an antibiotic treat: (a) influenza (b) the common cold (c) strep throat (d) measles?
Answer: (c). The others are viral. - Chromosomes line up across the middle of a dividing cell. Which phase of mitosis is it?
Answer: metaphase.
For 20 questions across all four science areas, take the TEAS science practice test.
A 10-day plan for TEAS biology
About 30 minutes a day: 20 minutes on one block of this page, 10 minutes of questions. Biology and chemistry are similar in size; anatomy and physiology is twice either, so if your date is close, give it the bigger share first.
| Day | Study | Done when you can |
|---|---|---|
| 1 | Prokaryotic vs eukaryotic, plant vs animal | Fill in the comparison table from memory |
| 2 | Organelles | Name the organelle for each job in the table |
| 3 | Membrane transport | Say which processes need ATP and why |
| 4 | Mitosis and meiosis | Put the phases in order; compare the two in 6 rows |
| 5 | DNA vs RNA, base pairing | Write the mRNA for any DNA template |
| 6 | Transcription, translation, codons, mutations | Explain why a frameshift does more harm than a substitution |
| 7 | Mendel and Punnett squares | Do the three worked squares without looking |
| 8 | Macromolecules and enzymes | Give the monomer, elements and a job for each of the four |
| 9 | Microorganisms and disease | Match each microbe to its treatment and an example |
| 10 | The 10 questions above, then a mixed science set | 9 of 10 right; reread the block for every miss |
Mistakes that cost points on TEAS biology
- Putting T in RNA. RNA uses uracil; A pairs with U.
- Mixing up mitosis and meiosis counts. Mitosis: 2 identical diploid cells. Meiosis: 4 different haploid cells.
- Reading a Punnett square for the wrong thing. Is the question asking for a genotype (Bb) or a phenotype (brown)?
- Calling codominance a blend. Codominance shows both (AB blood); incomplete dominance blends (pink).
- Thinking viruses are cells or that antibiotics treat them.
- Giving lipids a monomer. Lipids are built from glycerol and fatty acids, not a repeating monomer chain.
- Forgetting plants have mitochondria too. Chloroplasts make sugar; mitochondria still turn it into ATP.
TEAS biology FAQ
Is biology on the TEAS test?
Yes. Biology is one of the four science content areas on the TEAS 7: 9 of the 44 scored science questions.
What biology is on the TEAS 7?
Five topics in ATI's outline: cell structure and function (including mitosis and meiosis), DNA and protein synthesis, Mendel's laws, macromolecules, and microorganisms in disease.
Is there ecology or evolution on TEAS biology?
Neither is a named topic in ATI's Version 7 biology outline. Spend your hours on the five topics above first.
Is TEAS biology hard without a biology class?
It is manageable: the questions are introductory. Without a recent class, plan short daily sessions starting with cells and genetics; the 10-day plan above is built for that, and you can stretch each day over two if a topic is new.
How should I study for TEAS biology?
Learn each topic from a comparison table, then test yourself with questions the same day. Draw Punnett squares by hand until they take under a minute, and write the DNA-to-mRNA step for a few strands each day.
Sources
- ATI, ATI TEAS exam details (science questions, minutes, content areas). Read for our format guide, October 2026.
- ATI, ATI TEAS Version 7 content outline: the biology objectives.
- OpenStax, Biology 2e, Rice University: cells, transport, cell division, DNA and protein synthesis, Mendel, macromolecules.
- OpenStax, Microbiology, Rice University: bacteria, viruses, fungi, protozoa, antimicrobial drugs.
- Kingsborough Community College (CUNY), TEAS biology workshop outline: topic list. Read 2026-11-03.
More science guides: TEAS anatomy and physiology, TEAS chemistry, how to study for the TEAS science section, the TEAS science practice test, or all guides. To find out where biology stands against your other sections, take the free practice test: 15 questions, scored against your program's minimum.