TEAS 7 science study guide: body systems, DNA and worked examples

What to study for TEAS 7 science

The ATI outline includes human anatomy and physiology, biology, chemistry, and scientific reasoning. Keep all four in your plan. This guide selects a few recurring foundational distinctions; it does not cover every body system, every objective, or the reading, math and English portions of TEAS.

For each idea, write three things: what it does, what it is often confused with, and which fact would change your answer. Use the official outline as your coverage checklist. Use the linked government explanations to check the underlying science rather than treating the outline itself as a textbook.

• See ATI's science objectives on pages 4–5

Circulation: direction and oxygen content are different labels

An artery carries blood away from the heart; a vein returns blood toward it. Those names describe direction, not a universal oxygen level. In pulmonary circulation, oxygen-poor blood leaves the right ventricle through the pulmonary artery, while oxygen-rich blood returns from the lungs through pulmonary veins to the left atrium.

Worked example: a vessel takes blood from the heart to the lungs before oxygen is added. It is an artery because the flow is away from the heart. Calling it a vein just because the blood is oxygen-poor confuses two different properties. Now reverse the route: blood returning from the lungs travels through pulmonary veins even though it is oxygen-rich.

Recall cue: name the origin and destination before deciding the vessel type. Draw a short route in words, then separately label whether the blood has just reached or just left the lungs.

• Check the circulation route with NHLBI

Digestion and kidney function: absorption is not filtration

The small intestine absorbs digested nutrients into the body. The kidneys process blood, remove wastes and help regulate water and mineral balance. In a nephron, filtration occurs at the glomerulus; the tubule returns many needed substances to the blood, and remaining fluid contributes to urine.

Worked comparison: a description says nutrients are moving from digested food across an intestinal wall. That points to digestive absorption. A different description says substances in filtered fluid are being returned to blood before urine leaves the kidney. That points to renal reabsorption, not another step in moving food through the intestine.

The repair is to state where the material starts and where it goes. ‘Something is absorbed’ is too vague to identify the organ or process. Do not treat all filtered water as water that must be lost in urine.

• Read NIDDK's explanation of digestive absorption
• Read NIDDK's explanation of nephron function

DNA: apply complementary pairing one base at a time

DNA contains the bases A, T, C and G. In a double-stranded DNA molecule, A pairs with T and C pairs with G. Most human DNA is in the nucleus, but mitochondria also contain DNA, so ‘all DNA is in the nucleus’ is too absolute.

Worked example: at one position in a double-stranded DNA diagram, one strand has C. The base directly opposite it is G. At a position with A, the opposite base is T. Apply the pairing rule at each position instead of repeating the same letter on the other strand.

Keep this claim narrow: complementary DNA pairing is not a complete explanation of protein synthesis or inheritance. Those are separate outline skills to study. When a prompt changes the molecule or process, check the applicable rule instead of reusing a familiar answer automatically.

• Check DNA structure with MedlinePlus Genetics

Chemistry: a one-unit pH change is not a small linear step

For the simple aqueous examples used here, lower pH means more acidic conditions. The pH scale is logarithmic: a decrease of one unit represents a tenfold increase in hydrogen-ion activity. This is not a rule that a solution becomes ‘one unit more acidic’ in an ordinary linear sense.

Worked example: compare two otherwise comparable water samples with pH 4 and pH 6. The pH 4 sample has 10 × 10 = 100 times the hydrogen-ion activity of the pH 6 sample. It is not merely twice as acidic because the numbers differ by two. Conversely, going from pH 4 to pH 6 reduces that activity by a factor of 100.

Keep the comparison about pH. It does not establish whether a sample is safe to drink, what chemical is present, or what treatment it needs. The examples are for science preparation, not health or water-treatment advice.

• Read USGS's explanation of the pH scale

Experiments: separate what you change from what you measure

In a simple controlled experiment, the independent variable is deliberately varied. The dependent variable is the measured response. Controlled conditions are kept comparable so they do not offer a competing explanation. State these roles using the actual experiment, not just a memorized definition.

Worked example: a class plans to compare how long identical ice cubes take to melt in rooms held at different temperatures. The room temperature is the independent variable; elapsed melting time is the dependent variable. Starting cube size, container material and the definition of ‘fully melted’ should be consistent. This is an invented design example, not reported experimental data.

If larger cubes are also placed in the colder rooms, two conditions change together. A difference in melting time cannot then be attributed to temperature alone from that comparison. Keep the design fair, repeat measurements, and describe what the data supports without turning a limited observation into a universal claim.

• See NASA's variable definitions on page 10

A concise TEAS science study sheet

Use these prompts to check recall, then explain the reasoning without looking. They summarize the examples above, not the whole science outline. A compact sheet helps organize review; it cannot replace learning the missing systems or demonstrate readiness by itself.

1. Circulation: first label toward or away from the heart; then label oxygen content.
2. Organ systems: track what material moves, where it starts, and where it ends.
3. DNA: use the complementary pair, A–T or C–G; do not simply copy the same base.
4. pH: compare by powers of ten, with lower pH corresponding to higher hydrogen-ion activity.
5. Experiment: name the changed factor, measured outcome and conditions kept comparable.
6. Evidence: distinguish a supplied fact, your inference, and something the example does not establish.

Build the next study session around one distinction

If you mixed up an artery and a vein, do not just memorize one vessel name. Trace a different route and explain why its direction matters. If you mixed up variables, write a new experiment and identify the roles. If a pH comparison was wrong, calculate both directions and say which sample has greater hydrogen-ion activity.

Use a fresh example in a later session to see whether the reasoning transfers. Combine these checks with broader outline coverage. An isolated correct answer, a short diagnostic, or the ability to recite this sheet does not predict a TEAS result or admission to a program.

• Explore TEAS science guides and quick sheets
• Keep an error log with the free worksheet