Nokea
Steroid hormones function by binding to receptor proteins within the ________. Once the hormone binds to a receptor, it activates ______.
- A. nucleus: a second messenger
- B. nucleus: particular genes
- C. plasma membrane: a second messenger
- D. plasma membrane: particular genes
Correct Answer: B
Rationale: The correct answer is B because steroid hormones bind to receptor proteins in the nucleus, forming a hormone-receptor complex that directly influences the expression of specific genes. This process leads to the activation or repression of particular genes, resulting in changes in cellular functions. Choices A and C are incorrect because steroid hormones do not bind to receptors in the plasma membrane or use second messengers for signal transduction. Choice D is incorrect as steroid hormones do not directly regulate genes at the plasma membrane level.
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Atrial natriuretic hormone (ANH) is produced by cells of the ___.
- A. kidney tubules.
- B. right atrium of the heart.
- C. adrenal cortex.
- D. pancreas.
Correct Answer: B
Rationale: The correct answer is B: right atrium of the heart. Atrial natriuretic hormone (ANH) is produced by specialized cells in the right atrium of the heart called atrial myocytes. When the heart senses an increase in blood volume or pressure, these cells release ANH to help regulate fluid and electrolyte balance by promoting sodium and water excretion by the kidneys. Choices A, C, and D are incorrect because ANH is not produced by the kidney tubules, adrenal cortex, or pancreas. The primary site of ANH production is specifically within the cardiac atria.
Iodination of thyroid hormones is mediated by __________.
- A. lysosomes in the cell
- B. the Golgi apparatus
- C. colloid endocytosis
- D. peroxidase enzymes
Correct Answer: D
Rationale: The correct answer is D: peroxidase enzymes. Peroxidase enzymes are responsible for catalyzing the iodination process of thyroid hormones in the thyroid gland. They facilitate the incorporation of iodine atoms into tyrosine residues within thyroglobulin to form thyroid hormones T3 and T4. Lysosomes (choice A) are involved in cellular waste disposal, not iodination. The Golgi apparatus (choice B) is responsible for processing and packaging proteins, not iodination. Colloid endocytosis (choice C) is the process of internalizing colloid-containing vesicles in thyroid follicular cells, but it is not directly involved in iodination.
A newly developed pesticide has been observed to bind to an intracellular hormone receptor. If ingested, residue from this pesticide could disrupt levels of .
- A. melatonin
- B. thyroid hormone
- C. growth hormone
- D. insulin
Correct Answer: B
Rationale: Step-by-step rationale for why choice B (thyroid hormone) is correct:
1. Thyroid hormone is a key hormone that regulates metabolism and growth.
2. Intracellular hormone receptors are specific to certain hormones.
3. Disruption of thyroid hormone levels can lead to metabolic disorders.
4. Pesticide binding to the thyroid hormone receptor can interfere with its normal function.
Summary of why other choices are incorrect:
A: Melatonin regulates sleep-wake cycles, not metabolism.
C: Growth hormone regulates growth and development, not metabolism.
D: Insulin regulates blood sugar levels, not metabolism.
Gluconeogenesis occurs in the liver due to the action of ________.
- A. aldosterone
- B. insulin
- C. secretin
- D. cortisol
Correct Answer: D
Rationale: The correct answer is D: cortisol. Gluconeogenesis is the process of synthesizing glucose from non-carbohydrate sources, primarily in the liver. Cortisol plays a key role in stimulating gluconeogenesis by promoting the breakdown of proteins and fats to generate substrates for glucose production. Aldosterone, insulin, and secretin do not directly stimulate gluconeogenesis. Aldosterone regulates electrolyte balance, insulin promotes glucose uptake and storage, and secretin stimulates pancreatic enzyme secretion. Cortisol is the hormone responsible for activating gluconeogenesis in the liver.
The pituitary hormone that stimulates the male testes to produce sperm and stimulates the development of the follicle in the female on a monthly cycle is:
- A. growth hormone
- B. luteinizing hormone
- C. prolactin
- D. follicle-stimulating hormone
Correct Answer: D
Rationale: The correct answer is D: follicle-stimulating hormone (FSH). FSH is produced by the pituitary gland and plays a crucial role in both male and female reproductive systems. In males, FSH stimulates the testes to produce sperm. In females, FSH stimulates the development of ovarian follicles, which contain eggs. This hormone is essential for the process of ovulation and the menstrual cycle.
A: Growth hormone is not directly involved in the reproductive system but rather promotes overall growth and development.
B: Luteinizing hormone (LH) is responsible for ovulation and the production of testosterone in males. It does not directly stimulate sperm production or follicle development.
C: Prolactin is primarily involved in milk production and has no direct role in sperm production or follicle development.