ATI TEAS Practice Science Test

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.

Correct Answer: C

Rationale: The independent variable is the factor that is intentionally changed by the researcher. In this study, the type of road salt used is the independent variable because it is what the researcher is manipulating to observe its effect on the deicing time. The researcher can control and vary the type of road salt to measure its impact on the deicing process. The other choices are not the independent variable because: A (Deicing time period) is the dependent variable, B (Road used for deicing) is not something that the researcher is intentionally changing, and D (Amount of road salt used) is a controlled variable that can be adjusted but not the main factor being manipulated.

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: B

Rationale: The correct answer is B: Negative feedback. In this scenario, the body's response to a fever is an example of negative feedback mechanism. Negative feedback works to maintain homeostasis by reversing the direction of a change, in this case, reducing the fever to bring the body back to its normal temperature. This mechanism helps to regulate and stabilize bodily functions. Summary: A: Equal feedback is not a recognized type of feedback mechanism in biological systems. C: Neutral feedback does not actively regulate a response but rather allows it to continue unchanged. D: Positive feedback would amplify the fever response rather than work to reduce it and is usually seen in processes that need to be amplified, not regulated like in this scenario.

Correct Answer: C

Rationale: Rationale: 1. Aluminum has 13 electrons. 2. Based on the electron configuration rule (2n^2), the first shell can hold 2 electrons, the second shell can hold 8 electrons, and the third shell can hold 3 electrons. 3. Therefore, in a neutral aluminum atom, electrons are typically distributed as follows: 2 in the first shell, 8 in the second shell, and 3 in the third shell. 4. Choice C correctly reflects this electron distribution, making it the correct answer. Summary: A: Incorrect because it does not follow the electron configuration rule for aluminum. B: Incorrect as it does not distribute electrons according to the electron capacity of each shell in an aluminum atom. D: Incorrect because it does not match the electron distribution based on the electron configuration rule for aluminum.