Free TEAS 7 Science Practice Test 9 — 30 Questions With Full Explanations

Question 1. Biology medium

Water and dissolved mineral ions absorbed by root hairs travel upward through a plant mainly within which vascular tissue?

• A. Xylem (correct)
• B. Phloem
• C. Cambium
• D. Epidermis

Explanation: Xylem is the vascular tissue that conducts water and dissolved minerals from the roots to the shoots, driven by transpiration pull, cohesion, and root pressure. Phloem transports the sugars made by photosynthesis, the cambium is the meristem that produces new vascular tissue, and the epidermis is the protective outer cell layer.

Question 2. Scientific Reasoning medium

A diagnostic test has a false-positive rate of 4%, meaning it wrongly reports disease in 4 of every 100 healthy people. If 1,000 healthy people are tested, how many false-positive results are expected?

• A. 4
• B. 40 (correct)
• C. 96
• D. 400

Explanation: The expected number of false positives equals the false-positive rate times the number of healthy people tested: 0.04 x 1,000 = 40. The value 4 would be the expectation for only 100 people, 96 is the number of true negatives, and 400 would imply a 40% false-positive rate.

Question 3. Scientific Reasoning easy

A medical student measures the length of an adult human fingernail with a small ruler. Which unit will express the measured length as the most convenient whole-number value?

• A. Kilometers
• B. Meters
• C. Nanometers
• D. Millimeters (correct)

Explanation: An adult fingernail is roughly 10-15 mm long, so millimeters give a convenient whole-number reading such as 12 mm. Kilometers and meters are far too large for a fingernail, and nanometers are far too small, being the scale of individual molecules rather than a visible structure.

Question 4. Chemistry medium

Acetic acid (CH3COOH) is classified as a weak acid. When the acid dissolves in water, what proportion of its molecules actually ionize into H+ and CH3COO-?

• A. Essentially all of the molecules ionize completely
• B. Only a small fraction of the molecules ionize (correct)
• C. None of the molecules interact with the water
• D. The molecules release hydroxide ions instead of protons

Explanation: A weak acid such as acetic acid reaches an equilibrium in which only a small fraction of molecules donate a proton, so most remain as intact CH3COOH molecules. Strong acids ionize completely in water, bases release hydroxide ions, and even weak acids react measurably with water, making the other statements incorrect.

Question 5. Chemistry medium

A syringe sealed at the tip holds 40.0 mL of air at a pressure of 1.0 atm. If the plunger is pushed so the volume becomes 10.0 mL while the temperature stays constant, what is the new pressure inside the syringe?

• A. 0.25 atm
• B. 2.0 atm
• C. 4.0 atm (correct)
• D. 40.0 atm

Explanation: Boyle's law states that pressure and volume are inversely proportional at constant temperature, so P2 = P1 x V1 / V2 = 1.0 atm x 40.0 mL / 10.0 mL = 4.0 atm. The values 0.25 atm, 2.0 atm, and 40.0 atm do not follow from this inverse pressure-volume relationship.

Question 6. Scientific Reasoning medium

A balance displays 2.50 g for a certified standard whose true mass is 2.45 g. What is the absolute error of this single measurement?

• A. 0.05 g (correct)
• B. 0.50 g
• C. 2.5 g
• D. 5%

Explanation: Absolute error is the magnitude of the difference between the measured value and the true value: 2.50 g - 2.45 g = 0.05 g. The 0.50 g option confuses the decimal digits, 2.5 g is simply the measured mass, and 5% would be a relative error rather than an absolute error.

Question 7. Biology hard

During embryonic development, the decision for the bipotential gonads to become testes rather than ovaries is triggered by the activity of which gene located on the Y chromosome?

• A. CFTR
• B. HBB
• C. SRY (correct)
• D. TP53

Explanation: The SRY (sex-determining region Y) gene encodes a transcription factor that switches the bipotential embryonic gonad onto the testis pathway. CFTR mutations cause cystic fibrosis, HBB is the beta-globin gene that can carry sickle cell mutations, and TP53 is a tumor suppressor gene, so none of these determine gonadal sex.

Question 8. Chemistry hard

Of the following elements, which one requires the greatest amount of energy to remove its first electron, meaning it has the highest first ionization energy?

• A. Na
• B. Mg
• C. Al
• D. Si (correct)

Explanation: First ionization energy generally increases across a period as nuclear charge rises and atomic radius shrinks. Among Na, Mg, Al, and Si, silicon lies farthest to the right and does not show the 3s-to-3p dip seen with aluminum, so it holds its outermost electron most tightly and has the highest first ionization energy.

Question 9. Anatomy & Physiology medium

During blood clotting, the enzyme thrombin acts on the plasma protein fibrinogen to produce which insoluble protein that forms the mesh of the clot?

• A. Fibrin (correct)
• B. Albumin
• C. Globulin
• D. Hemoglobin

Explanation: Thrombin converts soluble fibrinogen into insoluble fibrin, which polymerizes into the threadlike mesh that traps platelets and red blood cells to form a stable clot. Albumin and globulin are transport proteins of the plasma, and hemoglobin carries oxygen inside red blood cells, so none of them form the clot mesh.

Question 10. Biology medium

Eukaryotic chromatin is organized into repeating beadlike units, each made of DNA wrapped around a core of eight histone proteins. These repeating units are known as which structures?

• A. Ribosomes
• B. Centromeres
• C. Nucleosomes (correct)
• D. Plasmids

Explanation: A nucleosome is the fundamental packaging unit of eukaryotic chromatin, consisting of roughly 147 base pairs of DNA wound around a core of eight histone proteins. Ribosomes synthesize proteins, the centromere is the chromosomal region where spindle fibers attach, and plasmids are small circular DNA molecules typical of bacteria, not nuclear packing units.

Question 11. Anatomy & Physiology medium

During childhood and adolescence, a long bone grows in length because the epiphyseal plate at each end is composed of which tissue, whose cells divide and are gradually replaced by bone?

• A. Dense fibrous connective tissue
• B. Smooth muscle
• C. Adipose tissue
• D. Hyaline cartilage (correct)

Explanation: The epiphyseal (growth) plate is a disc of hyaline cartilage whose chondrocytes proliferate and are progressively replaced by bone on the diaphyseal side, lengthening the shaft. Dense fibrous tissue forms ligaments and tendons, smooth muscle lines hollow organs, and adipose tissue stores fat, so none of these drive lengthwise bone growth.

Question 12. Anatomy & Physiology hard

In the loop of Henle, the descending limb is highly permeable to water but nearly impermeable to salts, while the ascending limb shows the opposite pattern. What is the main consequence of this arrangement?

• A. Sodium ions are actively secreted into the descending limb
• B. Water leaves the descending limb, steadily concentrating the fluid inside the tubule (correct)
• C. Glucose is reabsorbed by simple diffusion along the loop
• D. The filtrate becomes more dilute as it travels down the descending limb

Explanation: Because the descending limb lets water escape into the salty interstitial fluid while holding back solutes, the tubular fluid becomes progressively more concentrated as it descends. The ascending limb then pumps salt out without letting water follow, diluting the fluid. Glucose reabsorption occurs mainly in the proximal tubule, not in the loop.

Question 13. Chemistry easy

How much heat is needed to raise the temperature of 10.0 g of water by 5.0 C? (Specific heat of water = 1.00 cal per gram per degree C)

• A. 0.5 cal
• B. 5.0 cal
• C. 50 cal (correct)
• D. 500 cal

Explanation: Using q = mc delta T, the heat required is 10.0 g x 1.00 cal/(g C) x 5.0 C = 50 cal. The values 5.0 cal and 0.5 cal drop either the mass or the temperature change, and 500 cal would require ten times the mass or temperature rise.

Question 14. Anatomy & Physiology hard

A single somatic motor neuron together with every skeletal muscle fiber it innervates forms a functional unit in which a single action potential contracts all of those fibers together. What is this unit called?

• A. A myofibril
• B. A motor unit (correct)
• C. A fascicle
• D. A neuromuscular junction

Explanation: A motor unit is one motor neuron plus all the muscle fibers it supplies; whenever that neuron fires, every fiber in the unit contracts as a group, and finer control means smaller units. A myofibril is a rod of contractile proteins inside a fiber, a fascicle is a bundle of fibers, and the neuromuscular junction is the synapse itself.

Question 15. Chemistry easy

An atom's second principal energy level, n = 2, can hold at most how many electrons?

• A. 2
• B. 8 (correct)
• C. 18
• D. 32

Explanation: The capacity of a principal energy level is 2n^2, so the second level holds at most 2 x 2^2 = 8 electrons, filling one 2s and three 2p orbitals. Two electrons fit in the n = 1 level, 18 in n = 3, and 32 in n = 4.

Question 16. Anatomy & Physiology medium

Most of the watery sweat that evaporates and cools the body on a hot day comes from which type of gland located in the dermis?

• A. Apocrine sweat glands
• B. Sebaceous glands
• C. Ceruminous glands
• D. Eccrine (merocrine) sweat glands (correct)

Explanation: Eccrine sweat glands are the most numerous sweat glands; they secrete a watery, slightly salty fluid whose evaporation removes heat from the skin. Apocrine glands release a thicker, odor-prone secretion in the armpits and groin, sebaceous glands secrete oily sebum, and ceruminous glands produce earwax in the ear canal.

Question 17. Anatomy & Physiology easy

Roughly midway through the menstrual cycle, a brief surge of a hormone released by the anterior pituitary makes the mature ovarian follicle burst and release its egg. Which hormone is this?

• A. Thyroid-stimulating hormone (TSH)
• B. Growth hormone (GH)
• C. Luteinizing hormone (LH) (correct)
• D. Prolactin

Explanation: The mid-cycle LH surge is the trigger for ovulation, the release of the secondary oocyte from the mature ovarian follicle. TSH controls thyroid secretion, GH drives general body growth, and prolactin supports breast milk production, so none of these three prompt the release of an egg.

Question 18. Biology medium

In bacterial conjugation, one cell transfers a copy of a plasmid to a neighboring cell through which connecting structure?

• A. A flagellum
• B. An endospore
• C. A conjugation pilus (correct)
• D. A capsule

Explanation: The conjugation pilus is a hollow, hair-like tube that joins a donor and a recipient bacterium so that DNA, often a plasmid, can be transferred between them. A flagellum provides motility, an endospore is a dormant survival form, and a capsule is a protective outer coat, so none of these transfer DNA between cells.

Question 19. Biology hard

During oxidative phosphorylation, hydrogen ions flow down their concentration gradient through which enzyme complex embedded in the inner mitochondrial membrane, driving the synthesis of ATP?

• A. Rubisco
• B. ATP synthase (correct)
• C. Hexokinase
• D. DNA polymerase

Explanation: ATP synthase is the channel enzyme through which protons return to the mitochondrial matrix; the energy of that gradient powers the phosphorylation of ADP to ATP by chemiosmosis. Rubisco fixes carbon dioxide in photosynthesis, hexokinase phosphorylates glucose early in glycolysis, and DNA polymerase replicates DNA, none of which make ATP chemiosmotically.

Question 20. Anatomy & Physiology hard

Blood entering the glomerulus must cross three layers of the filtration membrane before it becomes filtrate. Which layer lies in direct contact with the blood inside the capillary?

• A. Basement membrane
• B. Visceral layer of the podocytes
• C. Fenestrated capillary endothelium (correct)
• D. Macula densa of the distal tubule

Explanation: The renal filtration membrane has three layers arranged from inside out: the fenestrated endothelium of the glomerular capillary, the basement membrane, and the podocyte slit diaphragms. The fenestrated endothelium is the innermost layer touching the blood, while the macula densa senses distal tubule fluid and is not part of the filter.

Question 21. Scientific Reasoning hard

During data analysis, a researcher notices that one participant's heart rate was recorded as 480 beats per minute, a value far outside the 60-100 range of everyone else. What is the most appropriate first step?

• A. Re-examine the original record or re-measure the value to check whether it was mistaken (correct)
• B. Average it together with the other values so it cannot distort the results
• C. Discard the entire data set and begin the study again
• D. Replace it with the highest value seen in any other participant

Explanation: An implausible outlier should first be checked against the original records or re-measured, because transcription and equipment errors are common and a valid extreme value should not be dropped without evidence. Averaging it in still allows it to distort the summary, restarting the study wastes the data already collected, and substituting another participant's value fabricates data.

Question 22. Scientific Reasoning easy

A line graph plots distance on the vertical axis and time on the horizontal axis, and the plotted line is perfectly flat. What does that flat line indicate about the object being studied?

• A. It is moving at a constant speed
• B. It is steadily speeding up
• C. It is steadily slowing down
• D. It is not moving (correct)

Explanation: On a distance-versus-time graph the slope equals speed, so a flat line with zero slope means distance is not changing and the object is stationary. A constant nonzero slope would mean constant speed, an increasing slope means acceleration, and a decreasing slope means deceleration.

Question 23. Chemistry easy

In a closed flask, 4.0 g of hydrogen gas reacts with 32.0 g of oxygen gas to produce exactly 36.0 g of water. Which principle does this outcome illustrate?

• A. The octet rule
• B. Activation energy
• C. The ideal gas law
• D. Conservation of mass (correct)

Explanation: Mass is neither created nor destroyed in a chemical reaction, so the mass of the products (36.0 g of water) exactly equals the total mass of the reactants (4.0 g + 32.0 g). The octet rule concerns electron configurations of atoms, activation energy is the energy barrier to a reaction, and the ideal gas law relates pressure, volume, moles, and temperature.

Question 24. Anatomy & Physiology medium

When food first enters the stomach, G cells release the hormone gastrin. What is the main effect of gastrin?

• A. It inhibits the release of bile from the liver
• B. It stimulates the gastric glands to secrete more acid (correct)
• C. It speeds the movement of chyme into the duodenum
• D. It triggers the gallbladder to empty

Explanation: Gastrin, secreted by G cells in the stomach wall, is the principal hormonal stimulant of gastric acid secretion because it activates the parietal cells and also promotes gastric motility. Bile release and gallbladder emptying are driven mainly by cholecystokinin, and the pyloric sphincter controls the passage of chyme, not gastrin.

Question 25. Anatomy & Physiology hard

A patient loses the ability to contract the muscles of facial expression on one side of the face while all other cranial nerve functions remain intact. Damage to which cranial nerve most directly explains this sign?

• A. Trigeminal (V)
• B. Glossopharyngeal (IX)
• C. Hypoglossal (XII)
• D. Facial (VII) (correct)

Explanation: The facial nerve (VII) innervates the muscles of facial expression, so damage to it produces the one-sided weakness typical of Bell's palsy. The trigeminal nerve (V) supplies the jaw muscles and facial sensation, the glossopharyngeal (IX) serves the pharynx and posterior tongue, and the hypoglossal (XII) moves the tongue.

Question 26. Anatomy & Physiology medium

A synovial joint such as the knee differs from a fibrous joint such as a suture of the skull mainly because the synovial joint contains which feature?

• A. A fluid-filled joint cavity (correct)
• B. Collagen fibers that bind the bones directly
• C. An interosseous membrane
• D. Dense irregular connective tissue

Explanation: Synovial joints are freely movable because the articulating bones are separated by a joint cavity filled with synovial fluid, which lubricates the surfaces and nourishes the articular cartilage. Fibrous joints such as skull sutures lack a cavity; their bones are linked directly by collagen fibers, interosseous membranes, or dense fibrous tissue.

Question 27. Scientific Reasoning medium

A bacterial culture grows from 2,000 cells to 2,500 cells. What is the percent increase in the population?

• A. 20%
• B. 25% (correct)
• C. 50%
• D. 125%

Explanation: Percent increase equals (new value - original value) divided by the original value, times 100: (2,500 - 2,000) / 2,000 x 100 = 25%. The 125% option compares the new count to the original without removing the original, and 20% and 50% do not match the actual ratio of the gain.

Question 28. Biology medium

During vigorous exercise, oxygen supply to working muscles can lag behind demand. Under these conditions, muscle cells convert pyruvate into which molecule so that glycolysis can continue generating ATP?

• A. Ethanol
• B. Acetyl CoA
• C. Lactate (correct)
• D. Carbon dioxide

Explanation: When oxygen is scarce, muscle cells reduce pyruvate to lactate in anaerobic fermentation, which regenerates the NAD+ that glycolysis requires to keep producing ATP. Ethanol fermentation occurs mainly in yeast, acetyl CoA feeds the aerobic Krebs cycle, and carbon dioxide is a byproduct of aerobic respiration, not of fermentation.

Question 29. Anatomy & Physiology medium

The liver detoxifies ammonia, a byproduct of protein breakdown, by converting it into a less toxic nitrogenous waste that the kidneys excrete in urine. What is that waste product?

• A. Urea (correct)
• B. Bilirubin
• C. Creatinine
• D. Glucose

Explanation: Ammonia is highly toxic to cells, so the liver combines it with carbon dioxide in the urea cycle to form urea, which is far less toxic and is eliminated by the kidneys in urine. Bilirubin is a pigment from hemoglobin breakdown, creatinine is a byproduct of muscle creatine, and glucose is a nutrient rather than a nitrogenous waste.

Question 30. Anatomy & Physiology hard

Lymph collected from the lower limbs, the abdomen, the left upper limb, and the left side of the head and neck empties into the bloodstream through which vessel?

• A. The thoracic duct (correct)
• B. The right lymphatic duct
• C. The hepatic portal vein
• D. The inferior vena cava

Explanation: The thoracic duct drains lymph from the lower body, the left upper limb, and the left side of the head and neck into the left subclavian vein. The right lymphatic duct serves only the right upper quadrant, the hepatic portal vein carries blood from the gut to the liver, and the inferior vena cava returns venous blood, not lymph.