Free TEAS 7 Science Practice Test 1 — 30 Questions With Full Explanations

Question 1. Anatomy & Physiology easy

Which organelle is the primary site of adenosine triphosphate (ATP) production in a human cell?

• A. Nucleus
• B. Ribosome
• C. Mitochondrion (correct)
• D. Golgi apparatus

Explanation: Mitochondria house the electron transport chain and most ATP synthesis. The nucleus stores DNA, ribosomes build proteins, and the Golgi apparatus modifies and packages proteins, so the other options do not produce ATP.

Question 2. Anatomy & Physiology easy

Which process moves water across a selectively permeable membrane from a low-solute region to a high-solute region?

• A. Facilitated diffusion
• B. Active transport
• C. Osmosis (correct)
• D. Phagocytosis

Explanation: Osmosis is the net movement of water toward the higher solute concentration so the two sides approach equilibrium. Facilitated diffusion and active transport move solutes, and phagocytosis engulfs particles.

Question 3. Anatomy & Physiology medium

During ventricular systole, the atrioventricular valves close primarily to

• A. speed up conduction through the atrioventricular node.
• B. prevent backflow of blood into the atria. (correct)
• C. allow blood to fill the coronary arteries.
• D. reduce pressure inside the ventricles.

Explanation: Ventricular contraction raises ventricular pressure above atrial pressure, so the closed AV valves stop blood from flowing backward into the atria. They do not speed conduction, fill coronary arteries, or lower pressure.

Question 4. Anatomy & Physiology medium

Which structure of the nephron is responsible for most reabsorption of filtered glucose?

• A. Glomerulus
• B. Proximal convoluted tubule (correct)
• C. Loop of Henle
• D. Collecting duct

Explanation: The proximal convoluted tubule reabsorbs nearly all filtered glucose along with most sodium and water. The glomerulus only filters, and the loop and collecting duct handle later adjustments, not bulk glucose reabsorption.

Question 5. Anatomy & Physiology medium

Gas exchange between alveolar air and pulmonary capillaries depends mainly on

• A. active transport of oxygen across the respiratory membrane.
• B. equal partial pressures of oxygen on both sides of the membrane.
• C. contraction of smooth muscle in the alveolar walls.
• D. differences in partial pressure driving diffusion of each gas. (correct)

Explanation: Each gas diffuses down its own partial-pressure gradient, oxygen into blood and carbon dioxide out. Nothing is actively transported in gas exchange, equal pressures would stop diffusion, and alveoli have no significant smooth muscle.

Question 6. Anatomy & Physiology medium

Hemoglobin carrying four oxygen molecules is described as

• A. fully saturated. (correct)
• B. oxygen-poor.
• C. carbaminohemoglobin.
• D. denatured.

Explanation: Saturation refers to how many of the four binding sites hold oxygen, so four-bound hemoglobin is fully saturated. The other terms describe low oxygen, carbon-dioxide-bound hemoglobin, or unfolded protein.

Question 7. Anatomy & Physiology easy

Which hormone, released by the pancreas, lowers blood glucose by promoting glucose uptake into cells?

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

Explanation: Insulin lowers blood glucose by stimulating cellular uptake and storage. Glucagon and cortisol raise glucose, and thyroxine regulates metabolic rate rather than glucose uptake directly.

Question 8. Anatomy & Physiology hard

In a resting neuron, the sodium-potassium pump maintains the resting membrane potential by

• A. exporting three sodium ions for every two potassium ions imported, both against their gradients. (correct)
• B. exporting two potassium ions for every three sodium ions imported.
• C. opening voltage-gated sodium channels continuously.
• D. balancing ion movement with an equal exchange of one sodium for one potassium.

Explanation: The pump moves 3 Na+ out and 2 K+ in per ATP, both against electrochemical gradients, creating the small negative interior charge. The other options reverse the ratio, describe gating, or predict no charge separation.

Question 9. Anatomy & Physiology medium

Which cells are primarily responsible for breaking down bone tissue during bone remodeling?

• A. Osteoblasts
• B. Osteocytes
• C. Chondrocytes
• D. Osteoclasts (correct)

Explanation: Osteoclasts resorb bone by dissolving mineral and digesting matrix. Osteoblasts build bone, osteocytes are mature bone cells that monitor strain, and chondrocytes make cartilage.

Question 10. Anatomy & Physiology medium

Lymph nodes function mainly to

• A. produce red blood cells.
• B. filter lymph and support immune responses. (correct)
• C. secrete digestive enzymes.
• D. store calcium.

Explanation: Lymph nodes filter lymph and house lymphocytes that mount immune responses. Red cell production is primarily marrow, digestive enzymes come from glands, and calcium storage is bone.

Question 11. Anatomy & Physiology easy

Which buffer system is the most important for stabilizing the pH of the blood?

• A. Bicarbonate-carbonic acid system (correct)
• B. Phosphate system
• C. Protein buffer system
• D. Ammonia buffer system

Explanation: The bicarbonate-carbonic acid pair is the dominant extracellular buffer of blood, reacting with both excess acid and excess base. The others help in cells, urine, or plasma but are secondary for blood pH.

Question 12. Anatomy & Physiology hard

According to the sliding filament model, muscle fiber shortening occurs when

• A. myosin heads pull actin filaments toward the center of the sarcomere. (correct)
• B. actin filaments slide away from the center of the sarcomere.
• C. sarcomeres lengthen as calcium is pumped back into the sarcoplasmic reticulum.
• D. myosin filaments shorten by folding on themselves.

Explanation: Cross-bridges form between myosin heads and actin, and each power stroke slides actin toward the sarcomere center, shortening the fiber. Actin never slides away, sarcomeres do not lengthen during contraction, and myosin does not fold.

Question 13. Biology easy

Which process produces four genetically distinct haploid cells from one diploid cell?

• A. Mitosis
• B. Meiosis (correct)
• C. Binary fission
• D. Budding

Explanation: Meiosis performs two divisions with one DNA replication, producing four haploid cells that differ genetically. Mitosis yields two identical diploid cells, and the other options are asexual processes.

Question 14. Biology medium

In the central dogma of molecular biology, the flow of information runs from

• A. protein to RNA to DNA.
• B. DNA to RNA to protein. (correct)
• C. RNA to DNA to RNA.
• D. protein to DNA directly.

Explanation: Transcription copies DNA into mRNA, and translation turns mRNA into protein, so the canonical direction is DNA to RNA to protein. The other orders reverse or shortcut that direction.

Question 15. Biology medium

Which stage of cellular respiration yields the most ATP per glucose molecule?

• A. Glycolysis
• B. Pyruvate oxidation
• C. Citric acid cycle
• D. Oxidative phosphorylation (correct)

Explanation: Oxidative phosphorylation drives the electron transport chain and chemiosmosis, producing roughly 30 of the ~32 net ATP from a glucose molecule. The earlier stages produce two ATP or a few, far less per glucose.

Question 16. Biology easy

Which feature distinguishes a eukaryotic cell from a prokaryotic cell?

• A. Ribosomes
• B. A plasma membrane
• C. A membrane-bound nucleus (correct)
• D. Cytoplasm

Explanation: Eukaryotes keep their DNA in a membrane-bound nucleus; prokaryotes have no nucleus. Ribosomes, plasma membranes, and cytoplasm are present in both cell types.

Question 17. Biology medium

An enzyme loses its ability to catalyze a reaction after being heated strongly. This loss of function is called

• A. denaturation. (correct)
• B. saturation.
• C. activation.
• D. inhibition by a competitive molecule.

Explanation: Strong heat unfolds the enzyme's three-dimensional structure, denaturing it so the active site no longer fits the substrate. Saturation and activation describe normal kinetics, and competitive inhibition is a reversible, specific block.

Question 18. Biology medium

In a monohybrid cross between two heterozygous parents (Aa x Aa), what proportion of offspring is expected to show the recessive phenotype?

• A. 1/2
• B. 1/3
• C. 1/4 (correct)
• D. 3/4

Explanation: The gamete ratio 1A:1a in each parent gives genotypic classes AA, Aa, aA, aa in equal quarters, so only the recessive homozygote, 1/4, shows the recessive phenotype. The other fractions come from miscounting the cross.

Question 19. Chemistry easy

A solution with a pH of 3 compared with a solution with a pH of 5 is

• A. ten times more acidic.
• B. one hundred times more acidic. (correct)
• C. ten times more basic.
• D. one hundred times more basic.

Explanation: Each pH unit is a tenfold change in hydrogen ion concentration, so two units means 100 times more acidic. The other options invert the direction or misapply the tenfold step.

Question 20. Chemistry medium

Which type of bond forms when electrons are shared between two nonmetal atoms?

• A. Ionic bond
• B. Covalent bond (correct)
• C. Metallic bond
• D. Hydrogen bond

Explanation: Covalent bonds share electron pairs between nonmetals. Ionic bonds transfer electrons between metal and nonmetal, metallic bonds involve delocalized electrons among metal atoms, and hydrogen bonds are weak intermolecular attractions.

Question 21. Chemistry medium

Elements in the same group of the periodic table are most similar in their

• A. atomic mass.
• B. number of neutrons.
• C. valence electron configuration. (correct)
• D. radioactivity.

Explanation: Same-group elements share valence electron configurations, which drives similar chemical behavior. Atomic mass and neutron number differ within a group, and radioactivity is not a group property.

Question 22. Chemistry hard

What is the molar mass of carbon dioxide (CO2)? (C = 12.0 g/mol, O = 16.0 g/mol)

• A. 22.0 g/mol
• B. 28.0 g/mol
• C. 44.0 g/mol (correct)
• D. 48.0 g/mol

Explanation: One carbon atom (12.0) plus two oxygen atoms (2 x 16.0 = 32.0) gives 44.0 g/mol. 22.0 halves the total, 28.0 counts only one oxygen, and 48.0 uses three oxygens.

Question 23. Chemistry medium

In the reaction HCl + NaOH yields NaCl + H2O, the hydrochloric acid and sodium hydroxide act as

• A. two acids.
• B. an acid and a base. (correct)
• C. a salt and water.
• D. an oxidizing and a reducing agent.

Explanation: HCl donates a proton and NaOH accepts it, the defining behavior of an acid and base in this neutralization. The products NaCl and water are the salt and the water, not the reactants' roles.

Question 24. Chemistry easy

Two atoms of the same element that differ in neutron number are called

• A. isotopes. (correct)
• B. isomers.
• C. ions.
• D. allotropes.

Explanation: Isotopes share the proton number but differ in neutrons, so atomic mass differs while chemical identity stays. Isomers are molecules with the same formula and different structure; ions carry a net charge; allotropes are structural forms of an element.

Question 25. Scientific Reasoning easy

A researcher states: If the new fertilizer raises soil nitrogen, then treated plots will show greener grass in four weeks. That statement is best classified as a

• A. hypothesis.
• B. conclusion.
• C. control.
• D. prediction. (correct)

Explanation: The statement is a specific, testable expectation stated as if-then, which is a prediction derived from a hypothesis. The hypothesis is the broader explanation; the conclusion comes after testing; a control is a comparison group.

Question 26. Scientific Reasoning medium

In an experiment testing the effect of water temperature on seed germination, which item is the control variable?

• A. The temperature of the water
• B. The number of seeds that germinate
• C. The type of seed used (correct)
• D. The amount of light during germination

Explanation: A control variable is held constant across groups, and using the same seed type keeps the test fair. Temperature is the manipulated variable, germination count is the measured outcome, and light must be controlled but the seed type is the natural answer among the choices.

Question 27. Scientific Reasoning medium

A study finds that cities with more ice cream sales also report more heat-related illness. Which conclusion is the most defensible?

• A. Ice cream causes heat-related illness.
• B. Nurses buy more ice cream in warm hospitals.
• C. A third factor, such as hot weather, plausibly links both variables. (correct)
• D. Heat-related illness causes ice cream sales to rise.

Explanation: Correlation alone does not prove causation, and warm weather offers a plausible common cause of both higher ice cream sales and more heat illness. The other conclusions assert cause-and-effect directions the study cannot support.

Question 28. Scientific Reasoning hard

A drug trial with 20 participants in each group finds a benefit, but a later trial with 2,000 participants per group finds none. The most likely explanation is

• A. the large trial used a weaker batch of the drug.
• B. the large trial measured the outcome incorrectly.
• C. drugs work only in small groups of patients.
• D. the small trial's result arose from sampling variability. (correct)

Explanation: Small samples fluctuate widely, so an apparent effect in 20 people is easily a chance result that evaporates in a large sample. The other explanations blame measurement or batch with no evidence.

Question 29. Scientific Reasoning medium

Which step makes a temperature-reading experiment most reliable?

• A. Reading the thermometer once at the end of the experiment.
• B. Taking multiple readings and reporting the average. (correct)
• C. Adjusting the thermometer until the expected value is shown.
• D. Using a different thermometer in each trial.

Explanation: Repeated measurements averaged together reduce the influence of single reading errors, improving reliability. One reading is prone to error, adjusting toward an expected value is biased, and changing thermometers adds instrument variability.

Question 30. Scientific Reasoning easy

Which activity belongs in the analysis stage of a scientific investigation?

• A. Writing the research question
• B. Recruiting participants
• C. Selecting the equipment
• D. Graphing the collected data (correct)

Explanation: After data are collected, graphing and summarizing them is analysis. The research question, equipment, and participants belong to the planning and execution stages that come earlier.