Nokea
Chemical signals that affect the behavior of other glands and tissues are _____.
- A. enzymes.
- B. hormones.
- C. carbohydrates.
- D. metabolites.
Correct Answer: B
Rationale: The correct answer is B: hormones. Hormones are chemical signals produced by glands that travel through the bloodstream to affect the behavior of other glands and tissues. Enzymes (choice A) are catalysts for chemical reactions, not signaling molecules. Carbohydrates (choice C) are energy sources and structural components, not signaling molecules. Metabolites (choice D) are the byproducts of metabolism, not signaling molecules. Hormones are specifically designed to regulate physiological processes in the body by acting on target cells, making them the most fitting choice among the options provided.
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Which of the following inhibits the secretion of growth hormone by the anterior pituitary?
- A. Sleep
- B. Stress
- C. Puberty
- D. Somatomedins
Correct Answer: D
Rationale: The correct answer is D: Somatomedins. Somatomedins, also known as insulin-like growth factors (IGFs), inhibit the secretion of growth hormone by negative feedback on the anterior pituitary. When somatomedins are present in sufficient levels, they signal to the pituitary gland to decrease the secretion of growth hormone.
A: Sleep does not directly inhibit the secretion of growth hormone. In fact, growth hormone is predominantly secreted during sleep.
B: Stress can stimulate the secretion of growth hormone, rather than inhibit it.
C: Puberty is a stage of development where growth hormone secretion is typically increased, not inhibited.
Which is a water soluble vitamin?
- A. D
- B. B12
- C. A
- D. K
Correct Answer: B
Rationale: The correct answer is B: B12. Vitamin B12 is water-soluble because it dissolves in water, allowing it to be easily absorbed and transported in the bloodstream. It plays a crucial role in nerve function, red blood cell production, and DNA synthesis. Vitamins D, A, and K are fat-soluble vitamins, meaning they are absorbed along with fats in the diet and are stored in the body's fat tissues. Since they are not water-soluble, they require bile for absorption and are stored in the body for longer periods. Hence, B12 is the only water-soluble vitamin among the given choices.
In its action in cells, aldosterone
- A. increases transport of ENaCs from the cytoplasm to the cell membrane
- B. does not act on the cell membrane
- C. binds to a receptor excluded from the nucleus
- D. may activate a heat shock protein
Correct Answer: A
Rationale: The correct answer is A because aldosterone increases the transport of epithelial sodium channels (ENaCs) from the cytoplasm to the cell membrane. This process leads to enhanced sodium reabsorption in the kidneys, promoting water retention and increasing blood pressure. Choices B and C are incorrect as aldosterone does act on the cell membrane and binds to a receptor located in the cytoplasm, which then translocates to the nucleus. Choice D is incorrect as aldosterone does not directly activate heat shock proteins.
What is the most critical need for the child with newly diagnosed cretinism?
- A. Thyroidectomy
- B. Administration of a radioactive cocktail of 131I (radioactive iodine)
- C. Replacement dose of thyroid hormones
- D. Replacement dose of calcitonin
Correct Answer: C
Rationale: The correct answer is C: Replacement dose of thyroid hormones. In newly diagnosed cretinism, there is a deficiency of thyroid hormones, leading to developmental delays and other health issues. Administering replacement thyroid hormones is crucial to normalize hormone levels and support proper growth and development. Thyroidectomy (choice A) is not necessary in this case as the goal is to supplement the missing hormones. Option B, the administration of radioactive iodine cocktail, is used to treat hyperthyroidism, not hypothyroidism. Choice D, replacement dose of calcitonin, is not relevant as calcitonin is involved in calcium regulation, not thyroid hormone production. Thus, the most critical need for the child with newly diagnosed cretinism is the replacement dose of thyroid hormones to address the underlying hormonal deficiency.
What is the formula of aluminium sulfate?
- A. Al2(SO4)3
- B. Al2(SO3)4
- C. Al4(SO4)2
- D. Al4(SO3)2
Correct Answer: A
Rationale: The correct formula for aluminium sulfate is Al2(SO4)3. This is because aluminium has a 3+ charge while sulfate has a 2- charge, requiring two aluminium ions to balance three sulfate ions. Choice B (Al2(SO3)4) is incorrect because sulfate ions have a 2- charge, not sulfite ions (SO3). Choices C (Al4(SO4)2) and D (Al4(SO3)2) have incorrect subscripts for the elements, not following the correct charge balance.