ATI TEAS 7 Science

Correct Answer: D

Rationale: The correct answer is D because water's unique polarity allows it to dissolve a wide range of substances. Water's polar covalent bonds enable it to form hydrogen bonds with other molecules, facilitating dissolution. Water's ability to dissolve various substances is crucial for biological processes such as nutrient absorption and waste removal. Choice A is incorrect because water is neutral in terms of its pH, not inherently having a neutral pH. Choice B is incorrect because water actually has a high specific heat capacity, which is why it can absorb and release large amounts of heat without significant temperature changes. Choice C is incorrect because while water does have polar covalent bonds, this property alone does not fully characterize water as much as its dissolving capabilities do.

Correct Answer: A

Rationale: Diastole is the correct answer because it specifically refers to the relaxation phase of the heart muscle. During diastole, the heart fills with blood before contracting in systole. Systole is the contraction phase, not relaxation. Asystole is the absence of heart contractions, not relaxation. Cardiastole is not a recognized term in relation to the heart's relaxation. Therefore, diastole is the most appropriate term for describing the relaxation of the heart muscle.

Correct Answer: B

Rationale: The correct answer is B: In a covalent bond, the shared electrons spend more time closer to the more electronegative atom. This is because the more electronegative atom attracts the electrons more strongly, causing them to be closer to that atom. This creates a partial negative charge on the more electronegative atom and a partial positive charge on the other atom. This distribution of electron density contributes to the stability of the covalent bond. Choices A, C, and D are incorrect because: A: Are completely transferred to one atom - This describes an ionic bond, not a covalent bond. C: Remain equidistant between the two atoms - Shared electrons in a covalent bond are not equidistant but are closer to one atom. D: Do not influence the bond strength - The distribution of shared electrons significantly influences the strength and properties of a covalent bond.

Correct Answer: C

Rationale: The correct answer is C: Control sleep-wake cycles. Melatonin is primarily responsible for regulating our sleep-wake cycles, also known as the circadian rhythm. This hormone is released by the pineal gland in response to darkness, signaling to the body that it is time to sleep. Melatonin helps to synchronize our internal body clock with the natural day-night cycle. Choice A (Regulate blood pressure) is incorrect because melatonin does not play a direct role in regulating blood pressure. Choice B (Stimulate the digestive system) is incorrect as melatonin is not involved in stimulating the digestive system. Choice D (Maintain bone density) is also incorrect as melatonin's primary function is not related to bone density regulation.

Correct Answer: B

Rationale: The correct answer is B: The ability to maintain a stable internal environment. Homeostasis is the body's ability to regulate and maintain a stable internal environment despite external changes. This includes maintaining stable levels of temperature, pH, and nutrients. Choice A is incorrect because homeostasis is not solely about body temperature. Choice C is incorrect as it does not encompass the overall concept of homeostasis. Choice D is incorrect because although regulating blood glucose levels is part of homeostasis, it does not fully capture the broad scope of maintaining a stable internal environment.