ATI TEAS Practice Science Test

Correct Answer: A

Rationale: The correct answer is A: Diffusion. Gas exchange in the respiratory system occurs through diffusion, where oxygen moves from the alveoli in the lungs to the blood and carbon dioxide moves from the blood to the alveoli. This process is driven by a concentration gradient, allowing for the exchange of gases between the air and blood. Exhalation (choice B) is the process of expelling air from the lungs, not the mechanism of gas exchange. Inspiration (choice C) is the process of inhaling air into the lungs, but it is not directly involved in gas exchange. Ventilation (choice D) refers to the movement of air into and out of the lungs and is necessary for gas exchange to occur but is not the actual mechanism of gas exchange itself.

Correct Answer: D

Rationale: The correct answer is D because it specifically refers to the process of selective permeability by stating that sodium ions must travel through ion channels to enter the cell. This demonstrates that the cell membrane allows certain substances to pass through while blocking others. Receptors on the cell's surface (A) and cell communication (B) are related to cell function but do not directly confirm selective permeability. Environmental changes affecting cell size (C) are more about cell response than membrane permeability. In summary, choice D is correct because it directly addresses the concept of selective permeability, while the other choices do not provide direct evidence of this property.

Correct Answer: A

Rationale: The correct answer is A: Cranial and spinal. The dorsal cavity is divided into two subdivisions: the cranial cavity, which contains the brain, and the spinal cavity, which houses the spinal cord. This division corresponds to the anatomical locations of these structures within the back of the human body. Explanation: 1. The cranial cavity is located in the skull, specifically protecting the brain. 2. The spinal cavity runs through the vertebral column, safeguarding the spinal cord. 3. These subdivisions are anatomically and functionally distinct, housing vital components of the central nervous system. Summary: B: Dorsal and ventral - Incorrect. Dorsal and ventral refer to the front and back sides of the body, not specific cavities within the back. C: Lateral and proximal - Incorrect. Lateral and proximal describe directions in relation to the body, not cavities within the back. D: Inferior and superior - Incorrect. Inferior and superior

Correct Answer: C

Rationale: The correct order is C: Thrombocytes, erythrocytes, and leukocytes. Thrombocytes (platelets) are the smallest, followed by erythrocytes (red blood cells), then leukocytes (white blood cells). This order is based on the size of these blood cell types, with thrombocytes being the smallest and leukocytes being the largest. Thrombocytes play a crucial role in blood clotting, erythrocytes are responsible for oxygen transport, and leukocytes are essential for immune function. Incorrect choices: A: Incorrect order; leukocytes are the largest, not the smallest. B: Incorrect order; thrombocytes are the smallest, not the largest. D: Incorrect order; leukocytes are larger than erythrocytes, so the order is incorrect.

Correct Answer: D

Rationale: The correct answer is D: Melanocyte-stimulating hormone. Melanocyte-stimulating hormone stimulates the melanocytes in the skin to produce melanin, the pigment responsible for skin color. This hormone darkens the skin by increasing melanin production. A: Follicle-stimulating hormone is involved in reproductive functions, not skin color changes. B: Growth-stimulating hormone primarily affects growth and development, not skin color. C: Thyroid-stimulating hormone regulates thyroid function, not skin color.