Free TEAS 7 Science Practice Test 5 — 30 Questions With Full Explanations

Question 1. Anatomy & Physiology easy

Which type of lymphocyte matures in the bone marrow and produces antibodies during an immune response?

• A. T lymphocyte
• B. Natural killer cell
• C. B lymphocyte (correct)
• D. Monocyte

Explanation: B lymphocytes mature in the bone marrow and differentiate into plasma cells that secrete antibodies. T lymphocytes mature in the thymus and mainly kill infected cells, natural killer cells attack abnormal cells nonspecifically, and monocytes become macrophages, so B cells are the antibody producers.

Question 2. Anatomy & Physiology easy

Which part of the eye changes shape to focus light onto the retina?

• A. Cornea
• B. Iris
• C. Sclera
• D. Lens (correct)

Explanation: The lens is a flexible, transparent structure whose curvature is adjusted by the ciliary muscles to focus light sharply on the retina. The cornea refracts light but does not change shape, the iris regulates light entry through the pupil, and the sclera is the protective outer coat, so the lens is correct.

Question 3. Anatomy & Physiology easy

Which blood type is the universal donor because its red blood cells lack A, B, and Rh antigens?

• A. A positive
• B. AB positive
• C. O negative (correct)
• D. B negative

Explanation: O negative red blood cells carry no A, B, or Rh antigens, so they do not trigger an immune attack when transfused into most recipients. AB positive is the universal recipient, while A positive and B negative still carry antigens that can cause reactions in incompatible recipients.

Question 4. Anatomy & Physiology medium

Which pancreatic hormone raises blood glucose by stimulating the liver to break down stored glycogen into glucose?

• A. Insulin
• B. Glucagon (correct)
• C. Cortisol
• D. Aldosterone

Explanation: Glucagon is secreted by the alpha cells of the pancreatic islets when blood glucose falls, prompting the liver to convert glycogen into glucose and release it. Insulin lowers blood glucose, cortisol raises it slowly during stress, and aldosterone regulates sodium, so glucagon is the correct hormone.

Question 5. Anatomy & Physiology medium

Which cells lining the stomach secrete hydrochloric acid and intrinsic factor?

• A. Parietal cells (correct)
• B. Chief cells
• C. Goblet cells
• D. Beta cells

Explanation: Parietal cells secrete hydrochloric acid, which activates pepsinogen and kills microbes, plus intrinsic factor needed for vitamin B12 absorption. Chief cells secrete pepsinogen, goblet cells produce mucus, and beta cells of the pancreas make insulin, making parietal cells correct.

Question 6. Anatomy & Physiology medium

Which hormone increases water reabsorption in the collecting ducts of the kidney, producing more concentrated urine?

• A. Aldosterone
• B. Antidiuretic hormone (ADH) (correct)
• C. Calcitonin
• D. Insulin

Explanation: Antidiuretic hormone, released by the posterior pituitary, makes the collecting ducts permeable to water so more is reabsorbed and urine becomes concentrated. Aldosterone mainly promotes sodium retention, calcitonin lowers blood calcium, and insulin controls glucose, so ADH is correct.

Question 7. Anatomy & Physiology medium

Which vitamin must be present for calcium to be absorbed efficiently from the small intestine?

• A. Vitamin D (correct)
• B. Vitamin K
• C. Vitamin C
• D. Vitamin B12

Explanation: Calcitriol, the active form of vitamin D, stimulates intestinal cells to make calcium-binding proteins that move calcium into the blood. Vitamin K supports clotting, vitamin C aids collagen synthesis, and vitamin B12 supports red cell formation, so vitamin D is required for calcium absorption.

Question 8. Anatomy & Physiology medium

Which structure of the inner ear converts sound vibrations into nerve impulses that travel to the brain?

• A. Tympanic membrane
• B. Cochlea (correct)
• C. Eustachian tube
• D. Semicircular canals

Explanation: The cochlea contains the organ of Corti, whose hair cells bend in response to fluid waves and generate action potentials in the auditory nerve. The tympanic membrane transmits vibrations, the eustachian tube equalizes pressure, and the semicircular canals sense rotation, so the cochlea is correct.

Question 9. Anatomy & Physiology medium

When body temperature rises, blood vessels in the skin dilate and sweating increases. This response is best described as

• A. negative feedback (correct)
• B. positive feedback
• C. feed-forward control
• D. active transport

Explanation: These responses oppose the original rise in temperature by increasing heat loss, which is the defining feature of negative feedback: the output counteracts the stimulus to restore the set point. Positive feedback amplifies a change, feed-forward anticipates it, and active transport moves molecules across membranes.

Question 10. Anatomy & Physiology hard

Which substance is secreted by type II alveolar cells and reduces surface tension so the alveoli do not collapse at the end of expiration?

• A. Mucus
• B. Surfactant (correct)
• C. Serous fluid
• D. Histamine

Explanation: Pulmonary surfactant, a mixture of phospholipids and proteins, lowers the surface tension of the fluid lining the alveoli, preventing collapse and reducing the work of breathing. Mucus traps particles, serous fluid lubricates membranes, and histamine mediates allergic responses, so surfactant is correct.

Question 11. Anatomy & Physiology hard

Baroreceptors that detect changes in blood pressure are located chiefly in which vessels?

• A. pulmonary capillaries and venules
• B. coronary arteries and cardiac veins
• C. carotid sinus and aortic arch (correct)
• D. renal glomeruli and peritubular capillaries

Explanation: The carotid sinus and the aortic arch contain mechanoreceptors that sense stretch and send signals adjusting heart rate and vessel tone to stabilize blood pressure. The other listed vessels lack major baroreceptor populations, making these two locations the correct answer.

Question 12. Anatomy & Physiology hard

In a spinal reflex arc, which neuron carries the sensory signal from the receptor into the spinal cord?

• A. Sensory (afferent) neuron (correct)
• B. Motor neuron
• C. Efferent neuron
• D. Schwann cell

Explanation: The sensory, or afferent, neuron conducts impulses from the receptor toward the central nervous system, where interneurons can synapse with motor neurons to produce a rapid response. Motor and efferent neurons carry signals away from the CNS, and Schwann cells form myelin, so the sensory neuron is correct.

Question 13. Biology easy

A true-breeding tall pea plant (TT) is crossed with a true-breeding dwarf plant (tt). If T is dominant, what percentage of the offspring will be tall?

• A. 0%
• B. 25%
• C. 50%
• D. 100% (correct)

Explanation: Every offspring receives T from one parent and t from the other, giving the genotype Tt in all cases. Because T is dominant over t, every Tt plant is tall, so 100 percent of the offspring exhibit the tall phenotype.

Question 14. Biology medium

Which nitrogenous base is present in RNA but not in DNA?

• A. Thymine
• B. Adenine
• C. Uracil (correct)
• D. Guanine

Explanation: RNA uses uracil in place of thymine and pairs it with adenine during transcription. Thymine is found in DNA, while adenine and guanine occur in both nucleic acids, so uracil is the base that uniquely identifies RNA.

Question 15. Biology medium

A sperm cell of an animal contains 19 chromosomes. How many chromosomes are present in a somatic (body) cell of the same animal?

• A. 9.5
• B. 19
• C. 38 (correct)
• D. 76

Explanation: Gametes are haploid (n), so n equals 19 for this animal. Somatic cells are diploid and contain two chromosome sets, giving 2 times 19, which equals 38 chromosomes in each body cell.

Question 16. Biology medium

During transcription, which enzyme reads a DNA template and assembles a complementary strand of messenger RNA?

• A. RNA polymerase (correct)
• B. DNA polymerase
• C. Helicase
• D. Ligase

Explanation: RNA polymerase binds to a promoter, unwinds the DNA, and builds mRNA by adding RNA nucleotides complementary to the template strand. DNA polymerase copies DNA during replication, helicase separates the strands, and ligase joins DNA fragments, so RNA polymerase performs transcription.

Question 17. Biology medium

A person with the genotype IAIB has blood type AB because both alleles are fully expressed. This pattern of inheritance is called

• A. incomplete dominance
• B. codominance (correct)
• C. sex-linked inheritance
• D. polygenic inheritance

Explanation: In codominance both alleles contribute equally to the phenotype, so the IA and IB alleles each produce their antigens, yielding blood type AB. Incomplete dominance produces a blended trait, sex-linked traits sit on sex chromosomes, and polygenic traits involve many genes.

Question 18. Biology hard

In a beetle population, green individuals are eaten by birds more often than brown individuals, and after many generations the population is mostly brown. This change is best explained by

• A. artificial selection
• B. genetic drift
• C. mutation pressure
• D. natural selection (correct)

Explanation: Birds act as an environmental pressure that differentially removes green beetles, so brown beetles reproduce more and their alleles spread through the population. Artificial selection requires human choice, genetic drift is random, and mutations alone do not sort alleles by fitness.

Question 19. Chemistry medium

What is the molar mass of calcium chloride (CaCl2)? (Ca = 40.1 g/mol, Cl = 35.5 g/mol)

• A. 75.6 g/mol
• B. 111.1 g/mol (correct)
• C. 118.0 g/mol
• D. 150.6 g/mol

Explanation: One calcium atom contributes 40.1 g/mol and two chlorine atoms contribute 2 times 35.5, which is 71.0 g/mol. Adding these contributions gives 111.1 g/mol for one mole of calcium chloride.

Question 20. Chemistry medium

A solution has a hydrogen ion concentration of 1.0 x 10^-4 M. What is the pH of this solution?

• A. 2
• B. 4 (correct)
• C. 6
• D. 10

Explanation: pH equals the negative base-10 logarithm of the hydrogen ion concentration. The logarithm of 1.0 x 10^-4 is -4, so pH = -(-4) = 4, which identifies a weakly acidic solution.

Question 21. Chemistry medium

When the equation C3H8 + O2 yields CO2 + H2O is balanced with whole-number coefficients, what is the coefficient of O2?

• A. 3
• B. 4
• C. 5 (correct)
• D. 6

Explanation: Balancing gives C3H8 + 5 O2 yields 3 CO2 + 4 H2O, verified by counting atoms: 3 carbons, 8 hydrogens, and 10 oxygens on each side. Therefore five oxygen molecules are required for complete combustion.

Question 22. Chemistry medium

How many grams are present in 2.0 moles of water? (Molar mass of H2O = 18.0 g/mol)

• A. 9.0 g
• B. 18.0 g
• C. 36.0 g (correct)
• D. 72.0 g

Explanation: Mass equals moles multiplied by molar mass, so 2.0 moles times 18.0 g/mol gives 36.0 grams. This is twice the mass of one mole of water, while 9.0, 18.0, and 72.0 grams correspond to other amounts.

Question 23. Chemistry easy

Which process is an example of a chemical change?

• A. Melting ice
• B. Boiling water
• C. Dissolving sugar in water
• D. Rusting of iron (correct)

Explanation: Rusting forms iron oxides, which are new substances with different properties, so the chemical composition of the iron changes. Melting, boiling, and dissolving only alter the physical state or the mixing while the substances themselves remain unchanged.

Question 24. Chemistry hard

Which element has the largest atomic radius?

• A. Rb (correct)
• B. Li
• C. Na
• D. K

Explanation: Atomic radius increases moving down a group because each element adds a new electron shell farther from the nucleus, with inner electrons shielding the outer ones. Rubidium is the lowest element listed, so it has the largest atomic radius.

Question 25. Scientific Reasoning medium

A student records reaction times of 0.24 s, 0.26 s, 0.20 s, 0.30 s, and 0.25 s in five trials. What is the mean reaction time?

• A. 0.20 s
• B. 0.24 s
• C. 0.25 s (correct)
• D. 0.30 s

Explanation: The mean is the sum of the measurements divided by the count: 1.25 s divided by 5 equals 0.25 s. The other options are single measurements or the minimum value rather than the computed average of all five trials.

Question 26. Scientific Reasoning easy

A researcher tests whether a new music training program improves math test scores. Which group serves as the control group in this experiment?

• A. students who receive the most intensive training
• B. the students who score highest on the pretest
• C. students whose parents sign a consent form
• D. students who receive no music training (correct)

Explanation: The control group receives no treatment, providing a baseline to compare against the trained group so any difference in math scores can be attributed to the training. The other groups receive the treatment or are defined by unrelated criteria.

Question 27. Scientific Reasoning hard

A graph of plant height versus fertilizer added rises steeply from 0 to 20 g, then levels off above 20 g. Which conclusion is best supported by the graph?

• A. height increases at the same rate at all fertilizer amounts
• B. fertilizer above 20 g adds little additional height (correct)
• C. more fertilizer always produces taller plants
• D. the graph shows no relationship between fertilizer and height

Explanation: Once the curve flattens beyond 20 g, additional fertilizer produces almost no further height gain, so plant growth has reached a plateau. This pattern rules out constant growth at all doses, unlimited increases, and the absence of any relationship.

Question 28. Scientific Reasoning hard

In a controlled experiment, seedlings under red light grew taller than seedlings under green light. Which conclusion is most defensible?

• A. red light causes all plants to grow taller regardless of species
• B. green light damages plant cells
• C. light color has no effect on plant growth
• D. in this experiment, plants under red light grew taller than plants under green light (correct)

Explanation: The result directly describes what was observed in this study, so the safest conclusion is limited to the comparison that was actually made. Claiming a universal cause, cell damage, or no effect at all goes beyond the evidence collected.

Question 29. Scientific Reasoning hard

A researcher wants to draw conclusions about all high school students in a region. Which sampling method best supports generalizing the results?

• A. a random sample of students from many different schools (correct)
• B. students from one classroom in one school
• C. students who volunteer from a single sports club
• D. the first ten students who arrive at one school

Explanation: Random sampling across many schools makes the sample representative of the whole region and minimizes selection bias. Convenience and volunteer samples drawn from single locations overrepresent narrow groups, so they generalize poorly to all students.

Question 30. Scientific Reasoning hard

In a trial with 400 participants, the drug group recovered in 3.1 days on average and the placebo group in 4.2 days, with p < 0.05. Which statement is most appropriate?

• A. the drug is guaranteed to cure every patient
• B. the placebo had no effect whatsoever
• C. every patient in the drug group recovered faster
• D. the difference is unlikely to be due to chance alone (correct)

Explanation: A p-value below 0.05 means the observed difference would occur by chance less than 5 percent of the time, so the result is statistically significant. It does not guarantee outcomes for individuals or prove that the placebo had no effect.