ATI TEAS Practice Science Test

Correct Answer: A

Rationale: The correct answer is A: They are small and soluble. Small molecules can easily diffuse across cell membranes, while soluble molecules can dissolve in the cell's aqueous environment. This combination allows the signals to pass through the membrane and bind to intracellular receptors. Choice B (large and soluble) is incorrect because large molecules have difficulty crossing the membrane. Choices C (small and insoluble) and D (large and insoluble) are incorrect as they do not facilitate the passage of signals across the cell membrane for binding to intracellular receptors.

Correct Answer: A

Rationale: The correct answer is A: Forms neural circuits. Interneurons are responsible for forming connections between sensory neurons and motor neurons, creating neural circuits that allow for complex processing and coordination of signals within the central nervous system. They do not directly interact with effectors (choice B), send impulses to the CNS (choice C), or function as efferent nerve cells (choice D). Interneurons integrate and relay information within the CNS, playing a crucial role in coordinating various functions such as reflexes, sensory processing, and motor control.

Correct Answer: D

Rationale: The correct answer is D because a taxonomic system classifies living things based on their molecular traits, allowing for a more accurate and scientific approach to categorizing organisms. This system helps in understanding evolutionary relationships and genetic similarities among species. Choice A is incorrect as behavior is not the primary focus of taxonomy. Choice B is not the main purpose of a taxonomic system, although naming new organisms is a part of it. Choice C is incorrect as distinguishing living things from nonliving things is more related to biology in general rather than specifically to taxonomy.

Correct Answer: C

Rationale: The correct answer is C because fetal waste is passed down the umbilical cord to the mother's circulatory system. The developing fetus eliminates metabolic wastes primarily through the placenta, which acts as a filter between the fetal and maternal circulatory systems. Metabolic wastes from the fetus, such as carbon dioxide and urea, diffuse through the placenta into the mother's bloodstream for elimination by her kidneys and lungs. This process ensures that the fetus's metabolic wastes are effectively removed without burdening its own developing organs. Choices A, B, and D are incorrect: A: The developing fetus does produce metabolic wastes, which need to be eliminated for proper development. B: Fetal waste does not pass through the mother's digestive system; it would be harmful to both the mother and fetus. D: Fetal waste does not exit the mother's body via the vagina; this is not a mechanism for waste elimination in utero.

Correct Answer: D

Rationale: The correct answer is D: Oxygen. 1. Oxygen has 8 electrons in total, with 2 in the first shell and 6 in the second shell, following the 2-8-8 electron configuration rule. 2. Beryllium has 4 electrons with 2 in the first shell and 2 in the second shell. 3. Carbon has 6 electrons with 2 in the first shell and 4 in the second shell. 4. Helium has 2 electrons, filling the first shell. Therefore, Oxygen is the only element among the choices that fits the description of having 2 electrons in the first shell and 6 electrons in the second shell.