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Which factor affects the gravitational potential energy of an object the most?
- A. The mass of the object
- B. The distance from the ground
- C. The gravitational force
- D. The shape of the object
Correct Answer: B
Rationale: Gravitational potential energy is directly proportional to the height or distance from the ground. As the object is raised higher, its gravitational potential energy increases. While the mass of the object influences gravitational potential energy, the distance from the ground has a more significant impact on it. The gravitational force does not directly affect the gravitational potential energy; it is the force that causes the potential energy to change with height. The shape of the object also does not determine gravitational potential energy, as it is primarily determined by the object's position in a gravitational field.
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Bile, a yellowish-green fluid, is stored in the gallbladder and released into the small intestine during digestion. What is the primary function of bile in digestion?
- A. Break down carbohydrates
- B. Break down proteins
- C. Emulsify fats
- D. Neutralize stomach acid
Correct Answer: C
Rationale: The primary function of bile in digestion is to emulsify fats. Bile contains bile salts that help break down large fat globules into smaller droplets, increasing the surface area for enzymes to work on and aiding in the absorption of fats in the small intestine. Choices A, B, and D are incorrect because bile's main role is not to break down carbohydrates or proteins, nor to neutralize stomach acid; rather, it primarily assists in the digestion and absorption of fats through emulsification.
An uncharged atom has an electron configuration of 1s² 2s² 2pⶠ3s² and a mass number of 14. How many protons does it have?
- A. 14
- B. 6
- C. 8
- D. 12
Correct Answer: B
Rationale: The number of protons in an atom is determined by the atomic number, which is equal to the number of protons in the nucleus. The electron configuration given corresponds to carbon (C) with 6 protons. The atomic number of an element is the same as the number of protons in its nucleus, so in this case, the atom has 6 protons. Choices A, C, and D are incorrect because they do not correspond to the correct number of protons for an atom with the given electron configuration and mass number. Therefore, option B, 6 protons, is the correct answer.
What is the primary function of the small intestine?
- A. To absorb water
- B. To absorb nutrients
- C. To store waste
- D. To produce enzymes
Correct Answer: B
Rationale: The correct answer is B: "To absorb nutrients." The small intestine's primary function is to absorb nutrients from digested food. It plays a crucial role in the digestion and absorption of nutrients such as proteins, carbohydrates, fats, vitamins, and minerals, which are essential for the body's functions and energy production. Choice A, "To absorb water," is incorrect because the absorption of water primarily occurs in the large intestine. Choice C, "To store waste," is incorrect as waste is stored in the large intestine before elimination. Choice D, "To produce enzymes," is incorrect because while the small intestine does receive enzymes from other organs to aid in digestion, its primary role is not enzyme production.
Which hormone, produced by the thyroid gland, plays a key role in regulating calcium levels in the blood by promoting calcium release from bones and increasing calcium reabsorption in the kidneys?
- A. Calcitonin
- B. Parathyroid hormone (PTH)
- C. Thyroxine
- D. Insulin
Correct Answer: A
Rationale: Calcitonin, produced by the thyroid gland, is responsible for regulating calcium levels in the blood. It works by decreasing blood calcium levels through two main mechanisms: promoting calcium uptake by bones and decreasing calcium reabsorption in the kidneys. Parathyroid hormone (PTH), on the other hand, increases blood calcium levels by promoting calcium release from bones and increasing calcium absorption in the intestines. Thyroxine, another thyroid hormone, primarily regulates metabolism and has no direct influence on calcium levels. Insulin, produced by the pancreas, is involved in regulating blood sugar levels and is not related to calcium homeostasis.
In nuclear physics, the term 'magic number' refers to specific numbers of protons or neutrons that contribute to:
- A. Increased nuclear instability
- B. Enhanced radioactive decay rates
- C. Exceptional stability of the nucleus
- D. All of the above
Correct Answer: C
Rationale: In nuclear physics, the term 'magic number' refers to specific numbers of protons or neutrons that lead to exceptional stability of the nucleus. These 'magic numbers' correspond to completely filled nuclear energy levels, resulting in increased stability rather than instability. Choice A, 'Increased nuclear instability,' is incorrect as magic numbers actually contribute to stability. Choice B, 'Enhanced radioactive decay rates,' is also incorrect as magic numbers do not affect decay rates but rather stability. Therefore, the correct answer is choice C, as magic numbers contribute to the exceptional stability of the nucleus.