Nokea
Which of the following is a common property of both acids and bases?
- A. React with metals to produce hydrogen gas
- B. Taste sour
- C. Turn blue litmus paper red
- D. Conduct electricity when dissolved in water
Correct Answer: D
Rationale: The correct answer is D. Both acids and bases can conduct electricity when dissolved in water. Acids ionize in water to produce H+ ions, which can carry an electric current, while bases ionize to produce OH- ions, which also conduct electricity. The other options are not common properties of both acids and bases. Reacting with metals to produce hydrogen gas is characteristic of acids, tasting sour is a property of acids, and turning blue litmus paper red is a property of bases, not a common property shared by both.
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In endocrine regulation, the feedback loop is a critical concept. In a negative feedback loop, high levels of a hormone can result in:
- A. Further stimulating the release of the same hormone
- B. Inhibiting the release of the hormone or its production
- C. Having no effect on the hormone's regulation
- D. Increasing the need for another hormone entirely
Correct Answer: B
Rationale: In a negative feedback loop, high levels of a hormone will inhibit the release of the hormone or its production. This mechanism is crucial for maintaining homeostasis by preventing excessive levels of hormones in the body. When a hormone reaches a certain concentration, it triggers the body to decrease its production or release, thereby ensuring a balance within the system. Choice A is incorrect because a negative feedback loop aims to counteract high hormone levels, not further stimulate them. Choice C is incorrect as high hormone levels do have an effect by triggering the feedback loop. Choice D is incorrect as the negative feedback loop operates within the same hormone system rather than increasing the need for an entirely different hormone.
Which hormone, produced by the adrenal glands, helps regulate the body's response to stress, including increasing blood pressure and suppressing the immune system?
- A. Aldosterone
- B. Epinephrine
- C. Cortisol
- D. Insulin
Correct Answer: C
Rationale: Cortisol is the correct answer. It is the hormone produced by the adrenal glands that helps regulate the body's response to stress. Cortisol plays a crucial role in increasing blood pressure and suppressing the immune system during stressful situations. Aldosterone, another hormone from the adrenal glands, primarily regulates salt and water balance in the body, not the stress response. Epinephrine, also known as adrenaline, is produced by the adrenal glands in response to stress, but its effects are more immediate and short-lived compared to cortisol. Insulin, produced by the pancreas, regulates blood sugar levels and is not directly involved in the body's response to stress.
Which of the following is NOT a function of the endoplasmic reticulum (ER)?
- A. Synthesis of lipids (fats)
- B. Transport of materials within the cell
- C. Detoxification of harmful substances
- D. Breakdown of cellular waste products
Correct Answer: D
Rationale: The endoplasmic reticulum (ER) is not involved in the breakdown of cellular waste products; this function is primarily carried out by lysosomes. The ER is responsible for the synthesis of lipids (fats), transport of materials within the cell, and detoxification of harmful substances. Lysosomes are the organelles responsible for breaking down cellular waste products through processes like autophagy. Therefore, option D is the correct answer as it does not align with the known functions of the endoplasmic reticulum.
Which blood type is considered a universal donor?
- A. A
- B. B
- C. AB
- D. O
Correct Answer: D
Rationale: Blood type O is considered the universal donor because individuals with type O blood can donate red blood cells to individuals with any ABO blood type (A, B, AB, or O) without causing an adverse reaction. Type O blood lacks A or B antigens on the surface of red blood cells, minimizing the risk of an immune response when transfused into individuals with different blood types. Therefore, type O blood is in high demand for blood transfusions in emergency situations when the recipient's blood type is unknown or when there is a shortage of specific blood types. Choices A, B, and AB are not considered universal donors. Individuals with blood types A, B, or AB can only donate to individuals with compatible blood types to avoid adverse reactions since they have A and/or B antigens on the surface of their red blood cells, making them incompatible with all blood types.
In nuclear fusion, where does the released energy originate from?
- A. The fission of heavy nuclei
- B. The binding energy released during the fusion of light nuclei
- C. Electronic transitions within atoms
- D. Matter-antimatter annihilation
Correct Answer: B
Rationale: The correct answer is B: 'The binding energy released during the fusion of light nuclei.' Nuclear fusion involves the combination of light nuclei to form a heavier nucleus, releasing energy in the process. This energy arises from the binding energy that keeps the nucleus intact. As lighter nuclei fuse, they create a more stable nucleus, and the excess energy is emitted as radiation. This fundamental process is the primary source of energy in stars and holds promise as a potential future energy source on Earth. Choices A, C, and D are incorrect. Choice A, 'The fission of heavy nuclei,' is related to nuclear fission, not fusion. Choice C, 'Electronic transitions within atoms,' refers to energy release in atomic transitions, not nuclear fusion. Choice D, 'Matter-antimatter annihilation,' is a process where matter and antimatter collide, converting their mass into energy, but it is not the energy source for nuclear fusion.