Free TEAS 7 Science Practice Test 3 — 30 Questions With Full Explanations

Question 1. Anatomy & Physiology easy

Which type of blood vessel carries blood away from the heart?

• A. Artery (correct)
• B. Capillary
• C. Vein
• D. Venule

Explanation: Arteries always carry blood away from the heart, whether the blood is oxygenated or not; the pulmonary artery, for example, carries deoxygenated blood to the lungs. Veins and venules return blood toward the heart, and capillaries connect the two sides for exchange, so artery is the correct term.

Question 2. Anatomy & Physiology medium

Which component of the blood is essential for clot formation and stopping bleeding?

• A. Red blood cells
• B. Platelets (thrombocytes) (correct)
• C. Plasma
• D. White blood cells

Explanation: Platelets stick to injured vessel walls, aggregate, and help form the fibrin clot that seals a wound. Red blood cells transport oxygen, white blood cells defend against infection, and plasma alone cannot aggregate into a plug, so platelets are the formed elements responsible for clotting.

Question 3. Anatomy & Physiology hard

Deoxygenated blood leaving the right ventricle travels next to which destination?

• A. The brain, through the carotid arteries
• B. The left atrium, directly
• C. The lungs, through the pulmonary arteries (correct)
• D. The aorta, for systemic distribution

Explanation: The right ventricle pumps deoxygenated blood into the pulmonary trunk, which divides into the pulmonary arteries that carry it to the lungs for gas exchange. The aorta distributes oxygenated blood from the left side, the left atrium receives pulmonary blood returning from the lungs, and the carotids supply the head, so the lungs are correct.

Question 4. Anatomy & Physiology easy

During inhalation, the diaphragm

• A. relaxes and moves upward, decreasing chest volume
• B. contracts and moves upward, compressing the lungs
• C. remains completely motionless
• D. contracts and moves downward, increasing the volume of the chest cavity (correct)

Explanation: Contraction flattens the dome-shaped diaphragm downward, enlarging the thoracic cavity and lowering pressure so air flows in. Relaxing would let it rise and expel air, an upward contraction would compress the cavity, and a motionless diaphragm could not drive quiet breathing, so the downward movement is correct.

Question 5. Anatomy & Physiology medium

Where does the exchange of oxygen and carbon dioxide between air and blood actually take place?

• A. Alveoli (correct)
• B. Bronchi
• C. Bronchioles
• D. Trachea

Explanation: Alveoli are the thin-walled air sacs wrapped in capillaries where gases diffuse between air and blood. The trachea, bronchi, and bronchioles are conducting airways that warm and route the air but have walls too thick for gas exchange, so the alveoli are the exchange surface.

Question 6. Anatomy & Physiology medium

Which enzyme, present in saliva, begins the chemical breakdown of starch in the mouth?

• A. Lipase
• B. Salivary amylase (correct)
• C. Pepsin
• D. Trypsin

Explanation: Salivary amylase starts splitting starch into shorter sugar chains while food is still in the mouth. Pepsin digests proteins in the stomach, trypsin digests proteins in the small intestine, and lipase digests fats, so none of those enzymes acts on starch in the oral cavity.

Question 7. Anatomy & Physiology medium

Which part of the digestive tract is the major site where digested nutrients are absorbed into the blood?

• A. Large intestine
• B. Stomach
• C. Small intestine (correct)
• D. Esophagus

Explanation: The small intestine's enormous surface area, created by villi and microvilli, absorbs most digested nutrients into the blood. The stomach mainly digests protein and absorbs very little, the large intestine absorbs mostly water, and the esophagus only transports food, so the small intestine is the absorption site.

Question 8. Anatomy & Physiology medium

Which part of a neuron receives incoming signals and conducts them toward the cell body?

• A. Axon
• B. Axon terminals
• C. Myelin sheath
• D. Dendrites (correct)

Explanation: Dendrites are the branched extensions that receive signals from other neurons and carry them toward the cell body. The axon conducts impulses away from the cell body, axon terminals release transmitter onto the next cell, and myelin only insulates the axon, so dendrites match the receiving role.

Question 9. Anatomy & Physiology hard

Which neurotransmitter is released at the neuromuscular junction to trigger skeletal muscle contraction?

• A. Acetylcholine (correct)
• B. Dopamine
• C. GABA
• D. Serotonin

Explanation: Motor neurons release acetylcholine at the neuromuscular junction, where it binds receptors on the muscle fiber and triggers contraction. Dopamine and serotonin are modulatory transmitters in the brain, and GABA is an inhibitory transmitter in the central nervous system, so acetylcholine is the junction chemical.

Question 10. Anatomy & Physiology medium

Which endocrine gland is often called the master gland because it releases hormones that control several other endocrine glands?

• A. Thyroid gland
• B. Pituitary gland (correct)
• C. Pineal gland
• D. Adrenal gland

Explanation: The pituitary secretes tropic hormones such as thyroid-stimulating hormone and gonadotropins that direct the thyroid, gonads, and other glands. The thyroid regulates metabolism, the adrenals manage stress responses, and the pineal makes melatonin, so the pituitary earns the master-gland label.

Question 11. Anatomy & Physiology hard

Which bone cell, a former osteoblast now embedded in the bone matrix, helps maintain the tissue and sense mechanical stress?

• A. Osteoblast
• B. Osteoclast
• C. Osteocyte (correct)
• D. Chondrocyte

Explanation: Osteocytes are mature bone cells trapped in the matrix they secreted; they maintain bone and detect mechanical strain. Osteoblasts build new bone on the surface, osteoclasts resorb bone, and chondrocytes produce cartilage, so osteocyte is the correct mature embedded cell.

Question 12. Anatomy & Physiology hard

During skeletal muscle contraction, the calcium ions that trigger the sliding of filaments are released from which structure?

• A. Golgi apparatus
• B. Neuromuscular junction
• C. Sarcolemma
• D. Sarcoplasmic reticulum (correct)

Explanation: The sarcoplasmic reticulum is a specialized calcium-storing membrane network inside the muscle fiber that floods the cytoplasm with calcium when stimulated. The sarcolemma is the muscle cell membrane, the Golgi apparatus packages proteins, and the neuromuscular junction is where the nerve meets the fiber, so the calcium comes from the sarcoplasmic reticulum.

Question 13. Biology easy

In which organelle does photosynthesis capture light energy and build glucose in plant cells?

• A. Chloroplast (correct)
• B. Ribosome
• C. Mitochondrion
• D. Vacuole

Explanation: Chloroplasts contain chlorophyll and carry out the light reactions and the Calvin cycle that build glucose. Mitochondria perform cellular respiration, vacuoles store water and solutes, and ribosomes synthesize proteins, so chloroplasts are the organelles where photosynthesis happens.

Question 14. Biology medium

Which organelle modifies, sorts, and packages proteins into vesicles for secretion from the cell?

• A. Rough endoplasmic reticulum
• B. Golgi apparatus (correct)
• C. Nucleolus
• D. Peroxisome

Explanation: The Golgi apparatus receives proteins from the rough endoplasmic reticulum, modifies them, and packages them into vesicles for delivery or export. The rough ER synthesizes the proteins but does not finalize them, the nucleolus makes ribosomal RNA, and peroxisomes break down fats, so the Golgi fits the sorting role.

Question 15. Biology medium

A normal human body cell contains 46 chromosomes. How many chromosomes are present in a human gamete such as an egg or sperm?

• A. 12
• B. 92
• C. 23 (correct)
• D. 46

Explanation: Gametes are haploid, carrying half of the somatic chromosome number, so 46 divided by 2 equals 23. Keeping 46 would mean no reduction before fertilization doubles the count, and the other values do not follow from halving, so 23 is the correct gamete number.

Question 16. Biology hard

During which stage of meiosis do homologous chromosomes separate from each other, reducing the chromosome number by half?

• A. Anaphase II
• B. Prophase II
• C. Metaphase I
• D. Anaphase I (correct)

Explanation: In anaphase I the homologous pairs are pulled apart, so each daughter cell receives one member of each pair and the chromosome number is halved. Anaphase II separates sister chromatids instead, prophase II follows the first division, and metaphase I aligns the pairs, so the halving occurs at anaphase I.

Question 17. Biology medium

What is the main function of messenger RNA (mRNA) in a cell?

• A. To carry the protein-building instructions from DNA in the nucleus to the ribosomes (correct)
• B. To deliver amino acids to the ribosome one at a time
• C. To form the structural core of the ribosome
• D. To copy the entire genome for storage in the cytoplasm

Explanation: mRNA is transcribed from a gene and carries that code to ribosomes, where it directs protein assembly. Transfer RNA delivers amino acids, ribosomal RNA forms the ribosome's structure, and no molecule copies the whole genome into the cytoplasm, so carrying instructions is mRNA's role.

Question 18. Biology easy

Which process splits one molecule of glucose into two molecules of pyruvate in the cytoplasm, producing a small amount of ATP?

• A. Krebs cycle
• B. Glycolysis (correct)
• C. Electron transport chain
• D. Beta oxidation

Explanation: Glycolysis is the cytosolic pathway that converts glucose into two pyruvate molecules with a net gain of two ATP. The Krebs cycle and electron transport chain occur in the mitochondria and process pyruvate's products, while beta oxidation breaks down fatty acids, so glycolysis fits this description.

Question 19. Chemistry medium

Which statement about electrons is correct?

• A. They are neutral particles with no charge
• B. They are the heaviest of the three main subatomic particles
• C. They are negatively charged particles that occupy regions around the nucleus (correct)
• D. They are packed inside the nucleus with the protons

Explanation: Electrons are negatively charged, very light particles distributed in shells or regions around the nucleus. Protons and neutrons are far heavier and sit inside the nucleus, and neutral particles are neutrons, so only the negative-charge-outside description of electrons is correct.

Question 20. Chemistry medium

An atom of carbon-14 has an atomic number of 6. How many neutrons does it contain?

• A. 6
• B. 20
• C. 14
• D. 8 (correct)

Explanation: The mass number of 14 equals protons plus neutrons, so subtracting the 6 protons leaves 8 neutrons. The value 6 is the proton count, 14 is the mass number itself, and 20 adds protons and neutrons instead of subtracting, so 8 is the correct number of neutrons.

Question 21. Chemistry medium

What type of chemical bond forms between a metal such as sodium and a nonmetal such as chlorine in sodium chloride?

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

Explanation: Sodium transfers its valence electron to chlorine, producing oppositely charged ions that attract each other in an ionic bond. Covalent bonds share electrons between nonmetals, hydrogen bonds are weak attractions between polar molecules, and metallic bonds hold metal atoms in a lattice, so ionic is correct.

Question 22. Chemistry medium

What is the molar mass of water (H2O)? (H = 1.0 g/mol, O = 16.0 g/mol)

• A. 16.0 g/mol
• B. 18.0 g/mol (correct)
• C. 17.0 g/mol
• D. 20.0 g/mol

Explanation: Two hydrogen atoms (2.0) plus one oxygen atom (16.0) total 18.0 g/mol. The 17.0 value undercounts one hydrogen, 16.0 equals oxygen alone, and 20.0 adds too much, so 18.0 g/mol is the correct molar mass of water.

Question 23. Chemistry hard

How many grams of sodium chloride (NaCl) are present in 0.50 moles? (Molar mass of NaCl = 58.4 g/mol)

• A. 116.9 g
• B. 58.4 g
• C. 29.2 g (correct)
• D. 14.6 g

Explanation: Multiplying 0.50 moles by the molar mass of 58.4 g/mol gives 29.2 g. The 58.4 g value is a full mole, 14.6 g is a quarter mole, and 116.9 g is two moles, so only 29.2 g matches half a mole of the salt.

Question 24. Chemistry easy

How many meters are in 2.5 kilometers?

• A. 25 m
• B. 250 m
• C. 25,000 m
• D. 2,500 m (correct)

Explanation: One kilometer equals 1,000 meters, so 2.5 kilometers is 2.5 times 1,000, or 2,500 m. The values 25 and 250 apply the wrong factors, and 25,000 multiplies by 10,000, so 2,500 m is the correct conversion.

Question 25. Scientific Reasoning easy

A researcher measures heart rate before and after volunteers drink caffeinated coffee. What is the dependent variable in this study?

• A. Heart rate (correct)
• B. The age of the volunteers
• C. The time of day the test is run
• D. The amount of coffee consumed

Explanation: The dependent variable is the outcome that is measured to detect an effect, which here is heart rate. The coffee amount is the independent variable being manipulated, while age and time of day are potential controlled variables, so heart rate is the dependent variable.

Question 26. Scientific Reasoning medium

A student testing a fertilizer waters the fertilized plants more often than the control plants and finds the fertilized group grows taller. The extra watering is best described as

• A. a placebo effect in the plants
• B. a confounding variable that weakens the claim about the fertilizer (correct)
• C. a reliable way to strengthen the conclusion
• D. the dependent variable of the experiment

Explanation: Because watering differed between the groups, the height difference could come from water rather than fertilizer, so the watering is a confounding variable. It is not the measured outcome, it does not improve the conclusion, and plants cannot experience placebo effects, so the description is confounding.

Question 27. Scientific Reasoning hard

Which combination of design elements is strongest for establishing that a treatment causes an observed effect?

• A. Comparing the treatment group with published national averages
• B. Observing a large group that chose the treatment on its own
• C. Random assignment to treatment and control groups with all other conditions kept identical (correct)
• D. Testing the treatment on one highly motivated volunteer

Explanation: Random assignment spreads unknown differences evenly between groups, and identical conditions leave the treatment as the only difference, which supports causation. Self-selected groups, historical comparisons, and single subjects leave confounding factors uncontrolled, so the randomized controlled design is strongest.

Question 28. Scientific Reasoning hard

A study reports a correlation of 0.9 between hours of study and exam scores. Which interpretation is most defensible?

• A. There is essentially no relationship between the two variables
• B. More study causes lower exam scores
• C. Studying definitely causes higher exam scores
• D. There is a strong positive association, but the study does not prove studying causes higher scores (correct)

Explanation: A correlation near 1.0 indicates a strong positive linear relationship, but observational data cannot rule out other influences such as motivation or prior knowledge, so causation is not established. The other choices either overstate causation or misread the direction and the strength of the association.

Question 29. Scientific Reasoning medium

A balance repeatedly reads 0.10 g for an object whose true mass is 0.15 g. The measurements are

• A. precise but not accurate (correct)
• B. both accurate and precise
• C. accurate but not precise
• D. neither precise nor accurate

Explanation: The readings cluster tightly together, showing precision, but they consistently miss the true value by the same amount, showing poor accuracy. Because the values agree with each other but not with the reference mass, only the precise-but-not-accurate description fits.

Question 30. Scientific Reasoning hard

A study draws firm conclusions about an entire adult population from only 10 participants. The most serious weakness is

• A. the independent variable is missing
• B. the small sample size limits how well the results generalize (correct)
• C. the results cannot be measured numerically
• D. a placebo group is always required

Explanation: With only 10 participants, random variation can dominate and the sample may not represent the population, so the findings generalize poorly. The results can still be numeric and include an independent variable, and a placebo is not required in every study, so sample size is the key flaw.