Nokea
How does AIDS impair the immune system?
- A. AIDS targets and destroys Helper T-Cells, preventing the activation of Cytotoxic T-Cells or B-Cells.
- B. IgE stimulates mast cells to release excessive histamine.
- C. IgE inhibits mast cells from releasing sufficient histamine.
- D. Helper T-Cells deceive the body into attacking itself.
Correct Answer: A
Rationale: AIDS targets and destroys Helper T-Cells, which play a crucial role in coordinating the immune response. By affecting these cells, AIDS prevents the activation of other important immune cells like Cytotoxic T-Cells or B-Cells. This disruption in the immune system's communication and response mechanisms leads to immune system failure and increased vulnerability to infections. Choices B and C are incorrect because they refer to the role of IgE in allergic reactions, which is not directly related to how AIDS impairs the immune system. Choice D is also incorrect as Helper T-Cells being destroyed in AIDS is not about deceiving the body into attacking itself, but rather the direct impact on immune system function.
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Which of the following glands is responsible for regulating the body's metabolism?
- A. Pituitary gland
- B. Thyroid gland
- C. Adrenal gland
- D. Pineal gland
Correct Answer: B
Rationale: The correct answer is B: Thyroid gland. The thyroid gland is responsible for regulating the body's metabolism by producing hormones like thyroxine. These hormones play a key role in controlling the body's metabolic rate and energy production. Choice A, the pituitary gland, is often referred to as the 'master gland' but is not primarily responsible for regulating metabolism. Choice C, the adrenal gland, is involved in producing hormones like adrenaline and cortisol, which are crucial for the body's stress response but not primarily for metabolism. Choice D, the pineal gland, is responsible for producing melatonin, which regulates sleep-wake cycles and not directly related to metabolic regulation.
According to the periodic table, which of the following elements is the least reactive?
- A. Fluorine
- B. Silicon
- C. Neon
- D. Gallium
Correct Answer: C
Rationale: Neon is the least reactive among the given elements because it belongs to the noble gases group in the periodic table. Noble gases have a full valence shell of electrons, making them highly stable and least likely to react with other elements. Fluorine is the most reactive non-metal due to its high electronegativity. Silicon is a metalloid with moderate reactivity, falling between metals and nonmetals. Gallium is a metal with higher reactivity compared to Neon, but it is not as reactive as Fluorine.
What term describes the front of the body, for example, the kneecap?
- A. Posterior
- B. Anterior
- C. Superior
- D. Inferior
Correct Answer: B
Rationale: The correct answer is 'B: Anterior.' In anatomy, 'anterior' refers to the front of the body, like the kneecap. On the other hand, 'posterior' describes the back of the body. Choices 'C: Superior' and 'D: Inferior' relate to structures being above or below a reference point, respectively, and are not used to describe the front or back of the body. Therefore, 'Anterior' is the most appropriate term given the context provided in the question.
A patient's body is not properly filtering blood. Which of the following body parts is most likely malfunctioning?
- A. Medulla
- B. Heart
- C. Nephrons
- D. Renal cortex
Correct Answer: C
Rationale: Nephrons are the functional units of the kidneys responsible for filtering blood and removing waste products to form urine. If a patient's body is not properly filtering blood, it is most likely due to dysfunction or impairment in the nephrons of the kidneys. The heart is responsible for pumping blood, not filtering it, making choice B incorrect. The medulla and renal cortex are specific parts of the kidney but do not directly perform the filtration function carried out by the nephrons, making choices A and D incorrect.
What is the electrical charge of the nucleus?
- A. A nucleus always has a positive charge.
- B. A stable nucleus has a positive charge, but a radioactive nucleus may have no charge and instead be neutral.
- C. A nucleus always has no charge and is instead neutral.
- D. A stable nucleus has no charge and is instead neutral, but a radioactive nucleus may have a charge.
Correct Answer: A
Rationale: A nucleus always has a positive charge. This is because the nucleus is composed of positively charged protons, along with neutral neutrons. The positive charge of the protons is balanced by the negative charge of the surrounding electrons in an atom, resulting in an overall neutral charge for the atom as a whole. Therefore, choice A is correct as it accurately reflects the positive charge of the nucleus due to the presence of protons. Choices B, C, and D are incorrect because they do not accurately represent the fundamental composition and charge distribution within an atom's nucleus. A stable nucleus consists of positively charged protons and neutral neutrons, leading to an overall positive charge, and not a neutral charge as suggested in the incorrect choices.