TEAS Scientific Reasoning practice questions

Experimental design, variables and controls, interpreting data, hypotheses and lab measurement. Scientific Reasoning is 9 of the 44 scored questions in TEAS Science.

scored questions

9

of Science's score

20%

for all of Science

60 min

1. 01Science · Scientific ReasoningIn a trial of a wristband device for motion sickness, 80 volunteers are randomly assigned to wear either an active wristband or an identical-looking inactive wristband, and none of the volunteers knows which one they have. The nurses who rate each volunteer's nausea on a 0–10 scale know which wristband each person wears. Which is the most likely remaining source of bias and its best remedy?+−

   • A. Selection bias; assign volunteers to groups more carefully by hand
   • B. Placebo effect; add an inactive wristband for comparison
   • C. Observer bias; keep the nurses unaware of each volunteer's group (correct)
   • D. Lack of a control group; remove the inactive wristbands

   Random assignment and an identical inactive wristband already address selection bias and the placebo effect. Nurses who know the group may rate nausea differently, so they should be blinded. Removing the inactive wristbands would eliminate the control group.

2. 02Science · Scientific ReasoningA bacterial culture is sampled at several times, and its optical density (a measure of cloudiness that rises with cell number) is recorded: 0 h = 0.10; 1 h = 0.18; 3 h = 0.50; 4 h = 0.74; 8 h = 1.50. During which interval was the average increase in optical density per hour the greatest?+−

   • A. 0 to 1 h
   • B. 1 to 3 h
   • C. 3 to 4 h (correct)
   • D. 4 to 8 h

   The average rates are 0.08/h for 0–1 h, 0.16/h for 1–3 h, 0.24/h for 3–4 h, and 0.19/h for 4–8 h, so 3–4 h is highest. The 4–8 h interval has the largest total change (0.76), but it spans four hours.

3. 03Science · Scientific ReasoningA hypothesis proposes that a stem bends toward light because the growth hormone auxin accumulates on the shaded side of the stem and makes the cells on that side elongate more. Which prediction follows logically from this hypothesis?+−

   • A. Cells on the lit side of a bending stem will be longer than cells on the shaded side.
   • B. Applying auxin evenly all around a stem in the dark will make the stem bend toward one side.
   • C. Blocking auxin from moving to the shaded side of a stem lit from one side will reduce its bending toward the light. (correct)
   • D. A stem lit evenly from all sides will bend more than a stem lit from one side.

   If shaded-side auxin causes the bending, preventing auxin from reaching that side should reduce the bending. Even application of auxin would elongate cells equally on all sides and give no bending, and the first option reverses the proposed mechanism.

4. 04Science · Scientific ReasoningA protocol requires 12 g of a liquid with a density of 0.80 g/mL. A 10 mL graduated cylinder reads to 0.1 mL, a 25 mL cylinder to 0.5 mL, and a 100 mL cylinder to 1 mL. A 250 mL beaker has only approximate markings. Which tool should be used to measure the liquid's volume most precisely?+−

   • A. The 10 mL graduated cylinder
   • B. The 100 mL graduated cylinder
   • C. The 25 mL graduated cylinder (correct)
   • D. The 250 mL beaker

   The volume is 12 g ÷ 0.80 g/mL = 15 mL. The 10 mL cylinder is too small to hold 15 mL, so the 25 mL cylinder is the most precise tool that can measure it. The 100 mL cylinder and the beaker are less precise.

5. 05Science · Scientific ReasoningIn a survey of 600 children ages 5 to 12, shoe size is strongly and positively correlated with reading test score. A researcher suspects that age explains this association. Which analysis would best test that suspicion?+−

   • A. Measure each child's shoe size more precisely.
   • B. Survey more children from each school.
   • C. Compare shoe size and reading score only among children who are the same age. (correct)
   • D. Give children larger shoes and see whether their reading scores rise.

   Comparing children of the same age removes age as a variable; if the association disappears, age was the confounder. Giving children larger shoes (D) tests whether shoe size causes better reading, not whether age explains the link.

6. 06Science · Scientific ReasoningA student plucks guitar strings of identical material and tension but different lengths (20, 30, 40, and 50 cm) and uses a tuner to record the pitch (frequency) each one produces. What is the independent variable in this experiment?+−

   • A. The frequency of the sound produced
   • B. The tuner used to measure pitch
   • C. The length of the string (correct)
   • D. The material of the strings

   The independent variable is the factor the experimenter deliberately changes, which here is string length. Frequency is the dependent variable that is measured, and material and tension are held constant.

7. 07Science · Scientific ReasoningCultured cells were kept for 24 h. Untreated cells had 90% viability at 24 h, and cells exposed to a test compound had 54% viability at 24 h. Treated cells' viability was what percentage of the untreated cells' viability?+−

   • A. 36%
   • B. 40%
   • C. 54%
   • D. 60% (correct)

   The comparison is relative to the untreated cells: 54 ÷ 90 = 0.60, or 60%. The value 54% ignores that the untreated cells also lost viability, and 36 is the difference in percentage points.

8. 08Science · Scientific ReasoningA researcher hypothesizes that night-migrating birds use star patterns to orient. Caged birds are placed in a planetarium, and when the projected star pattern is rotated 90°, the birds orient about 90° away from their original direction. Which conclusion is best justified?+−

   • A. The result proves that stars are the only cue migrating birds use
   • B. The result refutes the hypothesis because the birds did not head in their normal migration direction
   • C. The result shows that birds navigate mainly by magnetic fields
   • D. The result supports the hypothesis, since changing only the star pattern changed the orientation, but it does not rule out other cues in natural conditions (correct)

   The star pattern was the only thing changed and the orientation followed it, which supports the hypothesis. A single experiment that tests one cue cannot prove it is the only cue, and the rotated heading is exactly what the hypothesis predicts, so it does not refute it.

9. 09Science · Scientific ReasoningIn a trial of a sleep aid, 120 adults are randomly assigned to the sleep aid or to an identical-looking placebo pill, and participants do not know which they received. At follow-up, the physician who scores each participant's sleep quality on a subjective rating scale knows each participant's group. Which change would best address the remaining major source of bias?+−

   • A. Add a third group that receives no pill at all
   • B. Increase the sample size from 120 to 240 participants
   • C. Extend follow-up from 4 weeks to 8 weeks
   • D. Keep the rating physician unaware of each participant's group assignment (correct)

   A rater who knows the group assignments may unconsciously score the groups differently, and blinding the rater removes this observer bias. A larger sample reduces chance variation but does not remove bias, and a third group or a longer follow-up does not fix it either.

10. 10Science · Scientific ReasoningOrder the following stages in the typical path of a new scientific finding, from first to last.+−

    Correct order:

    1. Researchers analyze their data
    2. Researchers submit a manuscript to a journal
    3. Independent experts review the manuscript
    4. The journal publishes the article
    5. Other laboratories attempt to replicate the findings

    Data are analyzed first, then submitted, then peer reviewed before the journal publishes it. Replication by other labs normally follows publication.

Keep practicing

Sources

1. ATI: ATI TEAS exam details (sections, questions, sub-areas)

Updated November 6, 2026