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

Question 1. Anatomy & Physiology easy

Which bone is the longest and strongest bone in the human body?

• A. Femur (correct)
• B. Tibia
• C. Fibula
• D. Humerus

Explanation: The femur, the thigh bone, is the longest and strongest bone in the human body and bears most of the body weight during standing and walking. The tibia and fibula are lower-leg bones, and the humerus is the upper-arm bone, so those options are incorrect.

Question 2. Anatomy & Physiology easy

Which hormone stimulates uterine contractions during childbirth and triggers milk ejection from the mammary glands during breastfeeding?

• A. Insulin
• B. Aldosterone
• C. Oxytocin (correct)
• D. Thyroxine

Explanation: Oxytocin, released by the posterior pituitary gland, produces uterine contractions during labor and causes the let-down of milk during nursing. Insulin regulates blood glucose, aldosterone controls salt and water balance, and thyroxine sets the metabolic rate, so none of them performs these actions.

Question 3. Anatomy & Physiology medium

Which structure is the smallest functional unit of skeletal muscle contraction?

• A. Sarcomere (correct)
• B. Myofibril
• C. Sarcoplasmic reticulum
• D. Motor unit

Explanation: A sarcomere, the segment between two Z-discs, is the repeating functional unit in which actin and myosin filaments slide to shorten a muscle. A myofibril is a long chain of sarcomeres, the sarcoplasmic reticulum stores calcium ions, and a motor unit is one neuron with all the fibers it innervates.

Question 4. Anatomy & Physiology medium

Which structure controls the passage of chyme from the stomach into the duodenum?

• A. Ileocecal valve
• B. Pyloric sphincter (correct)
• C. Lower esophageal sphincter
• D. Anal sphincter

Explanation: The pyloric sphincter, located where the stomach meets the small intestine, regulates the release of chyme into the duodenum. The ileocecal valve separates the small from the large intestine, the lower esophageal sphincter guards the stomach entrance, and the anal sphincter controls the anus.

Question 5. Anatomy & Physiology medium

Which hormone, secreted mainly by the ovaries, is responsible for thickening the uterine lining during the proliferative phase of the menstrual cycle?

• A. Progesterone
• B. Follicle-stimulating hormone
• C. Human chorionic gonadotropin
• D. Estrogen (correct)

Explanation: Estrogen, dominant during the proliferative phase, drives regrowth of the endometrial lining after menstruation. Progesterone dominates after ovulation and supports the secretory phase, FSH stimulates follicle growth in the ovary, and hCG is produced by the placenta during pregnancy.

Question 6. Anatomy & Physiology medium

In which structure of the male reproductive system do sperm gain motility and complete their maturation?

• A. Seminiferous tubules
• B. Epididymis (correct)
• C. Prostate gland
• D. Vas deferens

Explanation: Sperm mature and acquire the ability to swim while being stored in the coiled epididymis on the back of each testis. Seminiferous tubules are where sperm are actually produced, the prostate gland adds fluid to semen, and the vas deferens simply carries sperm toward the urethra.

Question 7. Anatomy & Physiology medium

Which organ, located in the mediastinum behind the sternum, is the site where T lymphocytes mature?

• A. Spleen
• B. Thymus (correct)
• C. Thyroid gland
• D. Tonsils

Explanation: T lymphocytes develop and mature in the thymus, a lymphoid organ in the mediastinum that shrinks with age. The spleen filters blood and stores platelets, the thyroid gland secretes metabolic hormones, and the tonsils guard the entrance to the throat, so those options are incorrect.

Question 8. Anatomy & Physiology medium

Which cells release histamine during allergic reactions, causing vasodilation and increased capillary permeability?

• A. Mast cells (correct)
• B. Natural killer cells
• C. Helper T cells
• D. Erythrocytes

Explanation: Mast cells in connective tissue degranulate during allergic and inflammatory responses, releasing histamine that widens blood vessels and allows fluid to leak into tissues, producing swelling and redness. Natural killer cells destroy infected cells, helper T cells coordinate immunity, and erythrocytes transport oxygen.

Question 9. Anatomy & Physiology hard

Which cells of the kidney release renin when blood pressure in the afferent arteriole falls?

• A. Podocytes
• B. Juxtaglomerular cells (correct)
• C. Macula densa cells
• D. Mesangial cells

Explanation: Juxtaglomerular cells in the wall of the afferent arteriole secrete renin, which triggers the renin-angiotensin-aldosterone cascade that raises blood pressure. Podocytes form the filtration slits of the glomerulus, macula densa cells monitor sodium chloride in the tubule, and mesangial cells support the glomerular capillaries.

Question 10. Anatomy & Physiology hard

Which change in the blood is the strongest stimulus for increasing the rate and depth of breathing?

• A. A fall in arterial oxygen
• B. A rise in blood pH
• C. A fall in blood glucose
• D. A rise in arterial carbon dioxide (correct)

Explanation: Central chemoreceptors respond mainly to rising arterial carbon dioxide, which crosses into the cerebrospinal fluid, lowers its pH, and strongly drives faster and deeper breathing. A fall in oxygen is only a weaker secondary stimulus, a rising pH slows breathing, and blood glucose does not directly control ventilation.

Question 11. Anatomy & Physiology hard

A patient has a heart rate of 70 beats per minute and a stroke volume of 80 mL. What is the cardiac output in liters per minute?

• A. 0.875 L/min
• B. 5.6 L/min (correct)
• C. 56 L/min
• D. 5600 mL/min

Explanation: Cardiac output equals heart rate times stroke volume: 70 beats/min multiplied by 80 mL/beat gives 5,600 mL/min, which converts to 5.6 L/min. Dividing instead of multiplying gives 0.875, misplacing the decimal gives 56 L/min, and failing to convert milliliters to liters gives 5,600 mL/min.

Question 12. Anatomy & Physiology hard

Aldosterone raises blood pressure primarily by promoting the reabsorption of which ion in the distal tubule and collecting duct?

• A. Potassium
• B. Calcium
• C. Sodium (correct)
• D. Chloride

Explanation: Aldosterone acts on principal cells to increase sodium reabsorption, and water follows sodium osmotically, expanding blood volume and raising blood pressure. Potassium is secreted in exchange for sodium, while calcium and chloride are not the primary targets of this hormone's action.

Question 13. Biology easy

Which group of organisms has cell walls composed mainly of peptidoglycan?

• A. Fungi
• B. Plants
• C. Bacteria (correct)
• D. Animals

Explanation: Bacterial cell walls are built from peptidoglycan, a mesh of sugars cross-linked by short amino acid chains. Fungal cell walls contain chitin, plant cell walls are made of cellulose, and animal cells have no cell wall at all, so those options are incorrect.

Question 14. Biology medium

Which class of macromolecules is the primary long-term energy storage form in animals?

• A. Carbohydrates
• B. Lipids (correct)
• C. Proteins
• D. Nucleic acids

Explanation: Fats, a type of lipid, store more energy per gram than any other macromolecule and serve as the body's long-term energy reserve. Carbohydrates provide quick but short-lived energy, proteins mainly build and repair tissues, and nucleic acids store genetic information, not energy.

Question 15. Biology medium

Which type of RNA carries a specific amino acid to the ribosome during translation?

• A. Transfer RNA (correct)
• B. Messenger RNA
• C. Ribosomal RNA
• D. Small nuclear RNA

Explanation: Transfer RNA (tRNA) delivers activated amino acids to the ribosome, matching its anticodon to the codon on messenger RNA. Messenger RNA carries the protein blueprint from DNA, ribosomal RNA is a structural component of ribosomes, and small nuclear RNA participates in RNA splicing.

Question 16. Biology medium

During aerobic respiration, in which stage is carbon dioxide released as glucose is fully oxidized?

• A. Glycolysis
• B. The electron transport chain
• C. Fermentation
• D. The Krebs cycle (correct)

Explanation: The Krebs cycle, which runs in the mitochondrial matrix, releases carbon dioxide as carbon skeletons are oxidized, also generating NADH and FADH2. Glycolysis splits glucose without releasing carbon dioxide, the electron transport chain uses oxygen and forms water, and fermentation only regenerates NAD+.

Question 17. Biology hard

During DNA replication, which enzyme joins the Okazaki fragments on the lagging strand?

• A. Helicase
• B. Primase
• C. DNA ligase (correct)
• D. Topoisomerase

Explanation: DNA ligase seals the gaps between Okazaki fragments by forming phosphodiester bonds, producing a continuous lagging strand. Helicase unwinds the double helix, primase lays down short RNA primers, and topoisomerase relieves supercoiling ahead of the advancing replication fork.

Question 18. Biology hard

A child with Down syndrome has an extra copy of chromosome 21. How many chromosomes does each somatic cell of this child contain?

• A. 46
• B. 48
• C. 45
• D. 47 (correct)

Explanation: Humans normally have 46 chromosomes per somatic cell, and Down syndrome is caused by trisomy 21, meaning three copies of chromosome 21 instead of two, for a total of 47. Meiosis normally halves the number to 23 in gametes, and 45 or 48 would reflect a different chromosome-number error.

Question 19. Chemistry easy

How many valence electrons does a neutral atom of nitrogen have?

• A. 3
• B. 5 (correct)
• C. 7
• D. 14

Explanation: Nitrogen, in group 15 of the periodic table, has five valence electrons in its outer shell. Three is the number of covalent bonds nitrogen typically forms to complete its octet, seven is its atomic number, and fourteen is its most common mass number.

Question 20. Chemistry easy

Which element has the highest electronegativity of all the elements?

• A. Chlorine
• B. Oxygen
• C. Nitrogen
• D. Fluorine (correct)

Explanation: Fluorine, located in the upper right of the periodic table, has the highest electronegativity of any element because its small atom pulls shared electrons very strongly. Chlorine, oxygen, and nitrogen are all less electronegative than fluorine on the Pauling scale.

Question 21. Chemistry medium

According to the balanced equation 2 Na + Cl2 yields 2 NaCl, how many moles of sodium chloride are produced when 3.0 moles of sodium react completely with excess chlorine?

• A. 1.5 mol
• B. 2.0 mol
• C. 3.0 mol (correct)
• D. 6.0 mol

Explanation: The balanced equation shows a 2:2 mole ratio between sodium and sodium chloride, which reduces to 1:1, so 3.0 moles of sodium produce 3.0 moles of sodium chloride. Half that value ignores the 1:1 ratio, 2.0 mol does not follow from the given amount, and 6.0 mol wrongly assumes a 1:2 ratio.

Question 22. Chemistry medium

What is the empirical formula of glucose, which has the molecular formula C6H12O6?

• A. CH2O (correct)
• B. C6H12O6
• C. CHO
• D. C3H6O3

Explanation: The empirical formula is the simplest whole-number ratio of atoms, found by dividing every subscript by the greatest common factor, six, so C6H12O6 becomes CH2O. The molecular formula lists the actual atom counts in one molecule, and the other choices are not the reduced ratio.

Question 23. Chemistry hard

What is the oxidation number of sulfur in sulfuric acid, H2SO4?

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

Explanation: In H2SO4 each hydrogen is +1 (total +2) and each oxygen is -2 (total -8), so sulfur must be +6 to make the molecule neutral: +2 + x - 8 = 0, giving x = +6. The values +4, +2, and -2 would leave the compound with a nonzero overall charge.

Question 24. Chemistry hard

What is the oxidation number of oxygen in hydrogen peroxide, H2O2?

• A. -2
• B. +1
• C. -1 (correct)
• D. 0

Explanation: In H2O2 each hydrogen is +1, contributing +2 total, so the two oxygens must together equal -2, giving each oxygen an oxidation number of -1, the unusual value found in peroxides. Oxygen is -2 in most compounds, 0 as a free element, and never positive except with fluorine.

Question 25. Scientific Reasoning easy

Which question can be investigated using the methods of science?

• A. Is abstract art more beautiful than realistic art?
• B. Does fertilizer type affect tomato yield? (correct)
• C. Which flavor of ice cream is the best?
• D. Should the city raise taxes?

Explanation: Science investigates natural, testable questions with measurable outcomes, and the effect of fertilizer type on tomato yield can be settled with a controlled experiment. Beauty, taste preference, and tax policy depend on values and opinions, so experiments cannot resolve them.

Question 26. Scientific Reasoning medium

Which type of graph is most appropriate for comparing the average yield of five different crop varieties?

• A. Line graph
• B. Scatter plot
• C. Bar graph (correct)
• D. Pie chart

Explanation: A bar graph best compares distinct categories such as crop varieties because each bar shows one group's average value. A line graph shows trends across a continuous variable, a scatter plot shows the relationship between two measured variables, and a pie chart shows parts of a whole.

Question 27. Scientific Reasoning medium

A hypothesis predicts that warmer water speeds up seed germination. Which result would most weaken this hypothesis?

• A. Seeds in warm water and seeds in cold water germinate at the same rate (correct)
• B. Seeds in warm water germinate faster than seeds in cold water
• C. Seeds in cold water fail to germinate at all
• D. Warm water dissolves the outer seed coat

Explanation: Equal germination rates in warm and cold water directly contradict the prediction that warmth speeds germination, so this result most weakens the hypothesis. Faster germination in warm water supports it, and the other outcomes do not specifically test whether temperature changes germination speed.

Question 28. Scientific Reasoning medium

A researcher follows smokers and nonsmokers for ten years and records who develops lung disease without assigning anyone to a group. This study design is

• A. A randomized controlled trial
• B. A double-blind experiment
• C. A case study
• D. An observational study (correct)

Explanation: Because the researcher only observes and never assigns exposure, this is an observational study, which can reveal association but cannot prove causation. A randomized controlled trial assigns treatments by chance, a double-blind trial hides group membership, and a case study examines a single person in depth.

Question 29. Scientific Reasoning medium

A researcher defines aggression in a study as the number of times a child pushes another child during one hour. This measurable definition is called

• A. A hypothesis
• B. A control variable
• C. A confounding variable
• D. An operational definition (correct)

Explanation: An operational definition states exactly how a variable is measured, here counting pushes per hour, so that other researchers can reproduce the measurement. A hypothesis is a testable prediction, a control variable is held constant across groups, and a confounding variable is an unmeasured factor that could distort results.

Question 30. Scientific Reasoning hard

A researcher concludes that a new drug works when the observed difference is actually due to random chance. This mistake is called

• A. A Type I error (correct)
• B. A Type II error
• C. A confounding variable
• D. Sampling bias

Explanation: Concluding that an effect exists when random chance caused the observed difference is a Type I error, also called a false positive, because the null hypothesis was rejected when it was actually true. A Type II error misses a real effect, confounding is an unmeasured third variable, and sampling bias distorts who is included.