Free TEAS 7 Science Practice Test 4 — 30 Questions With Full Explanations

Question 1. Anatomy & Physiology easy

Which blood cells transport oxygen through the body?

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

Explanation: Red blood cells are packed with hemoglobin, which binds oxygen and carries it to the tissues. White blood cells and lymphocytes defend against infection, and platelets help form clots, so none of those transports oxygen through the body.

Question 2. Anatomy & Physiology medium

Which layer of the heart wall is the thick muscular layer that does the pumping?

• A. Pericardium
• B. Myocardium (correct)
• C. Endocardium
• D. Epicardium

Explanation: The myocardium is the layer of cardiac muscle whose contractions drive blood through the heart and vessels. The endocardium lines the inner chambers, the epicardium covers the outer surface, and the pericardium is the sac surrounding the heart, so the myocardium is the pumping muscle.

Question 3. Anatomy & Physiology medium

Which heart valve is located between the right atrium and the right ventricle?

• A. Bicuspid (mitral) valve
• B. Aortic valve
• C. Tricuspid valve (correct)
• D. Pulmonary valve

Explanation: The tricuspid valve guards the opening between the right atrium and the right ventricle. The bicuspid valve sits between the left atrium and left ventricle, the aortic valve exits the left ventricle, and the pulmonary valve guards the pulmonary trunk, so the tricuspid is the right-sided valve.

Question 4. Anatomy & Physiology easy

What is the primary function of the respiratory system?

• A. To produce digestive enzymes
• B. To filter waste products from the blood
• C. To regulate body temperature through sweating
• D. To exchange oxygen and carbon dioxide between the air and the blood (correct)

Explanation: The respiratory system moves air to the alveoli, where oxygen enters the blood and carbon dioxide leaves it. Filtering blood is the kidney's role, digestive enzymes come from digestive organs, and sweating is the skin's way of cooling the body, so gas exchange is the primary function.

Question 5. Anatomy & Physiology hard

Which lung volume is the amount of air that remains in the lungs even after the most forceful possible expiration?

• A. Residual volume (correct)
• B. Tidal volume
• C. Inspiratory reserve volume
• D. Vital capacity

Explanation: Residual volume is the air left after a maximal forced breath out, and it keeps the alveoli from collapsing. Tidal volume is a normal resting breath, vital capacity is the total breathable volume, and inspiratory reserve is the extra air inhaled beyond normal, so residual volume fits the description.

Question 6. Anatomy & Physiology medium

Which organ releases digestive enzymes and bicarbonate into the duodenum to break down nutrients and neutralize stomach acid?

• A. Gallbladder
• B. Pancreas (correct)
• C. Liver
• D. Appendix

Explanation: The pancreas secretes enzymes that digest carbohydrates, proteins, and fats, plus bicarbonate that neutralizes acidic chyme entering the duodenum. The liver makes bile, the gallbladder stores bile, and the appendix has no digestive function, so the pancreas is the enzyme-and-bicarbonate source.

Question 7. Anatomy & Physiology medium

Peristalsis, the movement of food through the digestive tract, is best described as

• A. random spasms of the intestinal wall
• B. gravity pulling food through the tract
• C. rhythmic waves of smooth muscle contraction that push contents forward (correct)
• D. chemical breakdown of food by enzymes

Explanation: Peristalsis is coordinated, wave-like contraction of smooth muscle that propels contents forward along the tract. Gravity plays little role against the tract's layout, spasms are abnormal and uncoordinated, and enzyme action is chemical digestion, so the wave description is correct.

Question 8. Anatomy & Physiology hard

Which region of the brain houses the centers that set the basic rhythm of breathing and heart rate?

• A. Hypothalamus
• B. Cerebrum
• C. Cerebellum
• D. Medulla oblongata (correct)

Explanation: The medulla oblongata contains autonomic centers that regulate the breathing rhythm and cardiac activity. The cerebellum coordinates movement, the cerebrum handles conscious functions, and the hypothalamus manages temperature and hunger, so the medulla controls the vital rhythms.

Question 9. Anatomy & Physiology hard

Which hormone, released by the thyroid gland, lowers blood calcium levels and opposes the action of parathyroid hormone?

• A. Calcitonin (correct)
• B. Aldosterone
• C. Thyroxine (T4)
• D. Glucagon

Explanation: Calcitonin, secreted by the parafollicular cells of the thyroid, lowers blood calcium by slowing bone resorption, opposing parathyroid hormone. Thyroxine regulates metabolic rate, aldosterone controls sodium and potassium balance, and glucagon raises blood glucose, so calcitonin is the calcium-lowering hormone.

Question 10. Anatomy & Physiology hard

During skeletal muscle contraction, calcium ions promote cross-bridge formation by

• A. breaking apart the actin filaments so myosin can attach
• B. binding to troponin, which shifts tropomyosin and exposes the actin binding sites (correct)
• C. binding directly to the myosin heads to start the power stroke
• D. triggering pumping of sodium out of the muscle fiber

Explanation: Calcium binds to troponin on the thin filament, which moves tropomyosin aside and exposes the actin sites where myosin heads attach. Calcium does not bind myosin heads directly, sodium pumping is a membrane event, and actin is not destroyed, so the troponin-tropomyosin sequence is correct.

Question 11. Anatomy & Physiology medium

Which tissue covers the ends of bones inside a joint, allowing smooth, low-friction movement?

• A. Ligament
• B. Periosteum
• C. Articular cartilage (correct)
• D. Tendon

Explanation: Articular cartilage is the smooth hyaline cartilage capping the ends of bones, reducing friction and absorbing impact in joints. The periosteum is the outer membrane of bone, ligaments connect bone to bone, and tendons connect muscle to bone, so articular cartilage is the joint surface tissue.

Question 12. Anatomy & Physiology medium

Which structure is the functional unit of the kidney where blood is filtered and urine is formed?

• A. Renal pelvis
• B. Urinary bladder
• C. Ureter
• D. Nephron (correct)

Explanation: Each nephron filters blood at its glomerulus and processes the filtrate into urine along its tubules. The ureter and bladder transport and store urine, and the renal pelvis collects urine before it enters the ureter, so only the nephron performs the filtering and forming work.

Question 13. Biology easy

Which structure surrounds every cell and controls which substances enter and leave?

• A. Plasma membrane (correct)
• B. Cytoskeleton
• C. Nucleus
• D. Cell wall

Explanation: The plasma membrane is the selective barrier of phospholipids and proteins that regulates what enters and leaves the cell. A cell wall is found in plants and bacteria but not animal cells, the nucleus stores DNA, and the cytoskeleton supports shape, so the plasma membrane is the gatekeeper.

Question 14. Biology medium

Which organelle contains digestive enzymes that break down worn-out organelles and cellular debris?

• A. Vacuole
• B. Lysosome (correct)
• C. Peroxisome
• D. Centriole

Explanation: Lysosomes are membrane-bound sacs of hydrolytic enzymes that digest waste and old organelles in animal cells. Peroxisomes process fatty acids and hydrogen peroxide, vacuoles store materials, and centrioles organize spindle fibers, so lysosomes are the digestive organelles.

Question 15. Biology medium

Which molecule serves as the final electron acceptor in the electron transport chain during aerobic respiration?

• A. Carbon dioxide
• B. Glucose
• C. Oxygen (correct)
• D. Water

Explanation: Oxygen accepts electrons at the end of the electron transport chain and combines with protons to form water, allowing ATP production to continue. Carbon dioxide is released by the Krebs cycle, glucose is the fuel being oxidized, and water is the product of the reaction, so oxygen is the final acceptor.

Question 16. Biology hard

A diploid organism has 40 chromosomes in its somatic cells. How many chromosomes will its gametes contain?

• A. 40
• B. 10
• C. 80
• D. 20 (correct)

Explanation: Meiosis halves the chromosome number, so gametes carry 40 divided by 2, or 20 chromosomes. Keeping 40 would make fertilization double the count, and the other values do not follow from halving the diploid number, so 20 is correct.

Question 17. Biology medium

An organism with the genotype Aa has two different versions of a gene. Which term describes this condition?

• A. Heterozygous (correct)
• B. Haploid
• C. Phenotypic
• D. Homozygous

Explanation: Heterozygous means carrying two different alleles of a gene, such as A and a. Homozygous means two identical alleles, phenotypic refers to the observable traits, and haploid describes a single set of chromosomes, so heterozygous is the correct term.

Question 18. Biology easy

Which molecules are the building blocks that join together to form proteins?

• A. Nucleotides
• B. Amino acids (correct)
• C. Fatty acids
• D. Monosaccharides

Explanation: Proteins are chains of amino acids linked by peptide bonds, so amino acids are their monomers. Nucleotides form nucleic acids, monosaccharides form carbohydrates, and fatty acids form lipids, so amino acids are the building blocks of proteins.

Question 19. Chemistry medium

Which two atoms are isotopes of each other?

• A. An atom with 6 protons and 6 electrons, and an identical atom with 6 protons and 6 electrons
• B. An atom with 6 protons and 7 neutrons, and an atom with 7 protons and 6 neutrons
• C. An atom with 6 protons and 6 neutrons, and an atom with 6 protons and 8 neutrons (correct)
• D. An atom with 12 protons and 12 neutrons, and an atom with 6 protons and 6 neutrons

Explanation: Isotopes of one element share the same proton number but differ in neutron number, so 6-proton atoms with 6 versus 8 neutrons are isotopes of carbon. The first distractor pairs different elements, the second pairs carbon with magnesium, and the third lists two identical atoms, so only the first pair is isotopic.

Question 20. Chemistry easy

Which state of matter has both a definite shape and a definite volume?

• A. Liquid
• B. Plasma
• C. Gas
• D. Solid (correct)

Explanation: Solids keep a fixed shape and volume because their particles vibrate in a rigid, ordered arrangement. Liquids have definite volume but take the shape of their container, and gases and plasma expand to fill any container, so solid is the state with both definite properties.

Question 21. Chemistry medium

At standard laboratory temperature, a solution with a pH of 7 is classified as

• A. Neutral (correct)
• B. Weakly basic
• C. Strongly basic
• D. Strongly acidic

Explanation: On the pH scale, 7 is neutral, with equal hydrogen and hydroxide activity, as in pure water. Values below 7 are acidic and values above 7 are basic, so labeling pH 7 as acidic or basic misplaces it on the scale.

Question 22. Chemistry medium

What is the molar mass of methane (CH4)? (C = 12.0 g/mol, H = 1.0 g/mol)

• A. 20.0 g/mol
• B. 16.0 g/mol (correct)
• C. 18.0 g/mol
• D. 13.0 g/mol

Explanation: One carbon atom (12.0) plus four hydrogen atoms (4.0) totals 16.0 g/mol. The 13.0 value adds only one hydrogen, 18.0 is the molar mass of water, and 20.0 overcounts the hydrogens, so 16.0 g/mol is the correct molar mass of methane.

Question 23. Chemistry hard

How many moles of carbon dioxide are present in 88.0 g of CO2? (Molar mass of CO2 = 44.0 g/mol)

• A. 4.0 moles
• B. 1.0 mole
• C. 2.0 moles (correct)
• D. 0.5 mole

Explanation: Dividing the mass by the molar mass, 88.0 g divided by 44.0 g/mol, gives 2.0 moles. One mole would weigh 44.0 g, half a mole would weigh 22.0 g, and four moles would weigh 176.0 g, so 2.0 moles is the only value that matches 88.0 g.

Question 24. Chemistry easy

How many milligrams are in 0.004 grams?

• A. 0.4 mg
• B. 400 mg
• C. 40 mg
• D. 4 mg (correct)

Explanation: One gram equals 1,000 milligrams, so 0.004 g multiplied by 1,000 is 4 mg. The value 0.4 mg divides instead of multiplying, and 40 mg and 400 mg misplace the decimal point, so 4 mg is the correct conversion.

Question 25. Scientific Reasoning medium

In an experiment testing how light affects seedling growth, every group is kept at the same temperature, watering, and soil. These matched conditions are the

• A. controlled variables (correct)
• B. experimental errors
• C. independent variables
• D. dependent variables

Explanation: Controlled variables are held constant across all groups so that only the independent variable differs. The independent variable is the light being changed on purpose, the dependent variable is the measured growth, and matched conditions are not errors, so controlled variables is the correct label.

Question 26. Scientific Reasoning easy

Which characteristic is required for a statement to qualify as a scientific hypothesis?

• A. It must never be revised
• B. It must be testable through observation or experiment (correct)
• C. It must agree with popular opinion
• D. It must already be proven true

Explanation: A hypothesis must generate testable predictions that can be supported or refuted by evidence. Being proven true is the goal of testing and cannot be known in advance, and popular opinion or inflexibility have no place in science, so testability is the defining feature.

Question 27. Scientific Reasoning medium

Why is a larger sample size generally preferred in a research study?

• A. It automatically proves causation
• B. It makes a control group unnecessary
• C. It reduces the influence of random variation on the results (correct)
• D. It guarantees the hypothesis is correct

Explanation: Larger samples average out random fluctuations, making estimates more reliable and more representative of the population. Sample size cannot guarantee a correct hypothesis, replace a control group, or prove causation, so reducing random variation is the key benefit.

Question 28. Scientific Reasoning medium

A thermometer consistently reads 0.5 degrees higher than the true temperature of a standard bath. This consistent offset is an example of

• A. a placebo effect
• B. a confounding variable
• C. random error
• D. systematic error (correct)

Explanation: A reproducible, same-direction deviation from the true value is systematic error, usually caused by miscalibration. Random error scatters readings unpredictably around the value, and placebo effects and confounding variables apply to studies of people rather than to instrument readings, so systematic error is correct.

Question 29. Scientific Reasoning hard

In a data set containing a few extreme outliers, why might a researcher prefer the median over the mean as a summary?

• A. The median is resistant to extreme values that would pull the mean away from the typical case (correct)
• B. The median is always larger than the mean
• C. The mean cannot be computed from ranked data
• D. The median ignores every value except the middle one

Explanation: The median depends on the position of values rather than their magnitude, so extreme outliers barely move it, while the mean is dragged toward them. The median is not always larger, a mean can be computed from any numeric data, and the median still reflects the ordered values, so resistance to outliers is the reason.

Question 30. Scientific Reasoning hard

Which action most directly improves the internal validity of an experiment testing a new diet's effect on weight loss?

• A. Measuring each group with a different scale
• B. Controlling diet and exercise so the groups differ only in the treatment being tested (correct)
• C. Reporting only the results that support the hypothesis
• D. Letting participants choose their own group

Explanation: Holding extraneous factors such as exercise constant ensures that any weight difference stems from the diet, which strengthens internal validity. Using different scales, allowing self-selection, and selective reporting introduce bias and error, so controlling the confounding factors is the correct move.