ATI TEAS Practice Science Test

Correct Answer: B

Rationale: The correct answer is B: Cytoplasm. Pyruvate is an intermediate product of glycolysis, which occurs in the cytoplasm of the cell. The biochemist isolating pyruvate is working with the cytoplasm because that's where glycolysis takes place. Chloroplasts (A) are involved in photosynthesis, not glycolysis. Mitochondria (C) are responsible for aerobic respiration, where pyruvate is eventually transported to. The nucleus (D) contains the cell's genetic material and is not directly involved in pyruvate metabolism. Thus, the biochemist is likely isolating pyruvate from the cytoplasm.

Correct Answer: A

Rationale: The correct answer is A: Artificial/active immunity. The MMR vaccine provides artificial immunity because it is a vaccine created in a laboratory rather than acquired naturally. It induces active immunity by stimulating the body to produce its antibodies against measles, mumps, and rubella. This type of immunity is long-lasting and provides protection by training the immune system to recognize and fight off these diseases in the future. Choice B (Artificial/passive) is incorrect because passive immunity involves receiving pre-formed antibodies rather than activating the immune system to produce its antibodies, which is the case with the MMR vaccine. Choice C (Natural/active) is incorrect because natural immunity is acquired through exposure to the actual disease, not through vaccination. Choice D (Natural/passive) is incorrect because natural passive immunity is passed from mother to baby through breast milk or placenta, not through vaccination.

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: 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: 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.