Practice Science TEAS Test

Correct Answer: C

Rationale: The correct answer is C: Iron (II). In heme, the central cation is Iron (II) because it forms a coordination complex with the porphyrin ring. Iron (II) has a +2 charge, allowing it to bind to the nitrogen atoms in the porphyrin ring. This binding is crucial for the proper functioning of heme in carrying oxygen in hemoglobin. Choice A (Cr III) is incorrect because chromium (III) does not typically bind to porphyrin rings in heme. Choice B (Cu II) is incorrect because copper (II) is not commonly found at the center of heme. Choice D (Iron III) is incorrect because in heme, iron is usually in the +2 oxidation state to efficiently bind and release oxygen. Iron (III) is not as effective in this role.

Correct Answer: D

Rationale: The independent variable is the factor that the researcher manipulates or controls. In this experiment, the independent variable is the dog food type as it is being purposely changed to observe its effect on the dependent variable. Time is not manipulated, dog weight and species are not changed intentionally, making them unsuitable as independent variables. The correct answer is D because it is the variable that is being tested and controlled in the experiment.

Correct Answer: B

Rationale: The correct answer is B: Cell membranes. Mesosomes are internal extensions of the cell membrane in prokaryotic cells. They are involved in cell division, DNA replication, and formation of respiratory enzymes. Choice A (Capsule) is incorrect because capsules are external structures surrounding the cell membrane. Choice C (Cell wall) is incorrect as mesosomes are not related to the cell wall, which provides structural support. Choice D (Chromatin body) is incorrect because chromatin bodies are found in eukaryotic cells, not prokaryotic cells where mesosomes are present.

Correct Answer: D

Rationale: The correct answer is D because the liver filters and detoxifies digestion byproducts. It processes nutrients from food, removes toxins, and metabolizes drugs. Choice A is incorrect because the liver produces bile, not just for digestion but also for waste elimination. Choice B is incorrect as the gallbladder stores bile. Choice C is incorrect as the liver converts waste ammonia into urea as part of the metabolic process, not specifically related to digestion.

Correct Answer: A

Rationale: Abduction is the movement away from the midline of the body. This is the correct answer because abduction refers to a lateral movement away from the body's midline, such as when raising your arms sideways. Option B is incorrect because it describes flexion, which decreases the angle of a joint. Option C is incorrect as it describes extension, increasing the angle of a joint. Option D is also incorrect as it describes adduction, moving towards the body's midline.