ATI TEAS Science 2026/2027 | ACTUAL-Style ATI
TEAS Science Practice Questions & Answers, TEAS 7
Science Exam Prep, Verified Answers, Detailed
Rationales, Human Anatomy & Physiology, Biology,
Chemistry, Scientific Reasoning, Cells, Tissues, Body
Systems, Genetics, DNA, Metabolism, Biochemistry,
Microbiology, Scientific Method, Experimental Design
& High-Yield TEAS Science Study Guide
Question 1: Which organelle is the primary site of adenosine
triphosphate (ATP) production via oxidative phosphorylation?
A. Ribosome
B. Golgi apparatus
C. Mitochondrion
D. Lysosome
CORRECT ANSWER: C. Mitochondrion
Rationale: The inner mitochondrial membrane houses the electron
transport chain and ATP synthase, coupling the oxidation of NADH and
FADH₂ to the phosphorylation of ADP, generating the majority of cellular
ATP. Ribosomes synthesize proteins, the Golgi apparatus modifies and
packages proteins, and lysosomes digest waste materials.
Question 2: The pulmonary artery transports blood from the right
ventricle to the lungs. What type of blood does it carry?
A. Oxygenated blood
B. Deoxygenated blood
C. Mixed oxygenated and deoxygenated blood
D. Nutrient-rich blood
CORRECT ANSWER: B. Deoxygenated blood
Rationale: The pulmonary artery is the only artery in the body that carries
deoxygenated blood, moving it to the pulmonary capillaries where gas
exchange oxygenates the blood. All other arteries carry oxygenated blood
away from the heart.
Question 3: Which layer of the skin contains blood vessels, nerve
endings, and hair follicles?
,A. Epidermis
B. Dermis
C. Hypodermis
D. Stratum corneum
CORRECT ANSWER: B. Dermis
Rationale: The dermis is the middle layer of the skin, rich in connective
tissue, blood vessels, sensory receptors, and appendages such as hair
follicles and glands. The epidermis is avascular, the hypodermis is the
deepest layer containing fat, and the stratum corneum is the outermost
epidermal layer.
Question 4: In a neuron at rest, the intracellular concentration of
which ion is higher than the extracellular concentration,
contributing to the resting membrane potential?
A. Sodium (Na⁺)
B. Chloride (Cl⁻)
C. Potassium (K⁺)
D. Calcium (Ca²⁺)
CORRECT ANSWER: C. Potassium (K⁺)
Rationale: Resting neurons maintain a high internal K⁺ concentration due to
Na⁺/K⁺-ATPase pumps, and leak channels allow K⁺ efflux, making the
interior negative relative to the outside. Sodium and chloride are higher
extracellularly, and calcium is primarily extracellular.
Question 5: What is the role of the enzyme helicase in DNA
replication?
A. Adding RNA primers
B. Unwinding the double helix
C. Joining Okazaki fragments
D. Synthesizing new DNA strands
CORRECT ANSWER: B. Unwinding the double helix
Rationale: Helicase breaks the hydrogen bonds between complementary
bases, separating the two strands to form the replication fork, allowing each
strand to serve as a template. Primase adds RNA primers, ligase joins
Okazaki fragments, and DNA polymerase synthesizes new strands.
,Question 6: A researcher manipulates the amount of light in a
growth chamber to study its effect on plant height. Which variable
is the independent variable?
A. Plant species
B. Growth chamber temperature
C. Amount of light
D. Plant height
CORRECT ANSWER: C. Amount of light
Rationale: The independent variable is the factor intentionally changed
(light amount); plant height is the dependent variable measured in
response. Plant species and temperature would be controlled variables kept
constant to prevent confounding results.
Question 7: Which of the following is a function of the large
intestine?
A. Secretion of digestive enzymes
B. Absorption of amino acids
C. Water and electrolyte reabsorption
D. Emulsification of fats
CORRECT ANSWER: C. Water and electrolyte reabsorption
Rationale: The large intestine absorbs water, sodium, and other electrolytes
from indigestible food matter, forming solid feces for elimination. Digestive
enzymes are secreted by the pancreas and small intestine, amino acids are
absorbed in the small intestine, and fats are emulsified by bile in the small
intestine.
Question 8: In the cardiac cycle, what does the QRS complex on an
electrocardiogram represent?
A. Atrial depolarization
B. Ventricular repolarization
C. Ventricular depolarization
D. Atrial repolarization
CORRECT ANSWER: C. Ventricular depolarization
Rationale: The QRS complex corresponds to depolarization of the
ventricles, which triggers ventricular contraction (systole). Atrial
, repolarization is masked by this larger electrical event, the P wave
represents atrial depolarization, and the T wave represents ventricular
repolarization.
Question 9: Which gland secretes melatonin, regulating the sleep-
wake cycle?
A. Pituitary gland
B. Pineal gland
C. Thyroid gland
D. Adrenal gland
CORRECT ANSWER: B. Pineal gland
Rationale: The pineal gland produces melatonin in response to darkness,
helping to synchronize circadian rhythms and sleep patterns. The pituitary
regulates other endocrine glands, the thyroid controls metabolism, and the
adrenal glands produce cortisol and adrenaline.
Question 10: Which of the following is improved when repeated
trials of an experiment have consistent results?
A. Validity
B. Reliability
C. Independent variables
D. Dependent variables
CORRECT ANSWER: B. Reliability
Rationale: Reliability speaks to the repeatability or consistency of an
experiment. When repeated trials yield consistent results, the experiment
demonstrates high reliability. Validity refers to whether the experiment
measures what it is intended to measure.
Question 11: Which of the following diseases is primarily caused by
a toxin produced by a microorganism?
A. Cholera
B. Leprosy
C. Acne
D. HIV
CORRECT ANSWER: A. Cholera
TEAS Science Practice Questions & Answers, TEAS 7
Science Exam Prep, Verified Answers, Detailed
Rationales, Human Anatomy & Physiology, Biology,
Chemistry, Scientific Reasoning, Cells, Tissues, Body
Systems, Genetics, DNA, Metabolism, Biochemistry,
Microbiology, Scientific Method, Experimental Design
& High-Yield TEAS Science Study Guide
Question 1: Which organelle is the primary site of adenosine
triphosphate (ATP) production via oxidative phosphorylation?
A. Ribosome
B. Golgi apparatus
C. Mitochondrion
D. Lysosome
CORRECT ANSWER: C. Mitochondrion
Rationale: The inner mitochondrial membrane houses the electron
transport chain and ATP synthase, coupling the oxidation of NADH and
FADH₂ to the phosphorylation of ADP, generating the majority of cellular
ATP. Ribosomes synthesize proteins, the Golgi apparatus modifies and
packages proteins, and lysosomes digest waste materials.
Question 2: The pulmonary artery transports blood from the right
ventricle to the lungs. What type of blood does it carry?
A. Oxygenated blood
B. Deoxygenated blood
C. Mixed oxygenated and deoxygenated blood
D. Nutrient-rich blood
CORRECT ANSWER: B. Deoxygenated blood
Rationale: The pulmonary artery is the only artery in the body that carries
deoxygenated blood, moving it to the pulmonary capillaries where gas
exchange oxygenates the blood. All other arteries carry oxygenated blood
away from the heart.
Question 3: Which layer of the skin contains blood vessels, nerve
endings, and hair follicles?
,A. Epidermis
B. Dermis
C. Hypodermis
D. Stratum corneum
CORRECT ANSWER: B. Dermis
Rationale: The dermis is the middle layer of the skin, rich in connective
tissue, blood vessels, sensory receptors, and appendages such as hair
follicles and glands. The epidermis is avascular, the hypodermis is the
deepest layer containing fat, and the stratum corneum is the outermost
epidermal layer.
Question 4: In a neuron at rest, the intracellular concentration of
which ion is higher than the extracellular concentration,
contributing to the resting membrane potential?
A. Sodium (Na⁺)
B. Chloride (Cl⁻)
C. Potassium (K⁺)
D. Calcium (Ca²⁺)
CORRECT ANSWER: C. Potassium (K⁺)
Rationale: Resting neurons maintain a high internal K⁺ concentration due to
Na⁺/K⁺-ATPase pumps, and leak channels allow K⁺ efflux, making the
interior negative relative to the outside. Sodium and chloride are higher
extracellularly, and calcium is primarily extracellular.
Question 5: What is the role of the enzyme helicase in DNA
replication?
A. Adding RNA primers
B. Unwinding the double helix
C. Joining Okazaki fragments
D. Synthesizing new DNA strands
CORRECT ANSWER: B. Unwinding the double helix
Rationale: Helicase breaks the hydrogen bonds between complementary
bases, separating the two strands to form the replication fork, allowing each
strand to serve as a template. Primase adds RNA primers, ligase joins
Okazaki fragments, and DNA polymerase synthesizes new strands.
,Question 6: A researcher manipulates the amount of light in a
growth chamber to study its effect on plant height. Which variable
is the independent variable?
A. Plant species
B. Growth chamber temperature
C. Amount of light
D. Plant height
CORRECT ANSWER: C. Amount of light
Rationale: The independent variable is the factor intentionally changed
(light amount); plant height is the dependent variable measured in
response. Plant species and temperature would be controlled variables kept
constant to prevent confounding results.
Question 7: Which of the following is a function of the large
intestine?
A. Secretion of digestive enzymes
B. Absorption of amino acids
C. Water and electrolyte reabsorption
D. Emulsification of fats
CORRECT ANSWER: C. Water and electrolyte reabsorption
Rationale: The large intestine absorbs water, sodium, and other electrolytes
from indigestible food matter, forming solid feces for elimination. Digestive
enzymes are secreted by the pancreas and small intestine, amino acids are
absorbed in the small intestine, and fats are emulsified by bile in the small
intestine.
Question 8: In the cardiac cycle, what does the QRS complex on an
electrocardiogram represent?
A. Atrial depolarization
B. Ventricular repolarization
C. Ventricular depolarization
D. Atrial repolarization
CORRECT ANSWER: C. Ventricular depolarization
Rationale: The QRS complex corresponds to depolarization of the
ventricles, which triggers ventricular contraction (systole). Atrial
, repolarization is masked by this larger electrical event, the P wave
represents atrial depolarization, and the T wave represents ventricular
repolarization.
Question 9: Which gland secretes melatonin, regulating the sleep-
wake cycle?
A. Pituitary gland
B. Pineal gland
C. Thyroid gland
D. Adrenal gland
CORRECT ANSWER: B. Pineal gland
Rationale: The pineal gland produces melatonin in response to darkness,
helping to synchronize circadian rhythms and sleep patterns. The pituitary
regulates other endocrine glands, the thyroid controls metabolism, and the
adrenal glands produce cortisol and adrenaline.
Question 10: Which of the following is improved when repeated
trials of an experiment have consistent results?
A. Validity
B. Reliability
C. Independent variables
D. Dependent variables
CORRECT ANSWER: B. Reliability
Rationale: Reliability speaks to the repeatability or consistency of an
experiment. When repeated trials yield consistent results, the experiment
demonstrates high reliability. Validity refers to whether the experiment
measures what it is intended to measure.
Question 11: Which of the following diseases is primarily caused by
a toxin produced by a microorganism?
A. Cholera
B. Leprosy
C. Acne
D. HIV
CORRECT ANSWER: A. Cholera
