Correct Answer: (d)
Steroid hormones are lipophilic (lipid-soluble). This property allows them to diffuse directly across the plasma membrane of target cells. Once inside, they typically bind to intracellular receptors that move into the nucleus to act as transcription factors, directly influencing gene expression.
Q2. A patient with a pituitary tumor exhibits fatigue, weight loss, and low blood sugar. This is probably due to a lack of production of
Correct Answer: (b)
Adrenocorticotropic hormone (ACTH) triggers the adrenal cortex to release glucocorticoids like cortisol. Cortisol is vital for maintaining blood glucose levels. A lack of ACTH leads to low cortisol, causing hypoglycemia (low blood sugar) and chronic fatigue.
Q3. Mild vitamin D deficiency can lead to osteoporosis, or reduced bone mineral density. This is thought to be due to an association with increased levels of
Correct Answer: (b)
Vitamin D is necessary for calcium absorption from the gut. When Vitamin D is low, blood calcium drops, triggering the parathyroid glands to release more Parathyroid Hormone (PTH). PTH increases blood calcium by breaking down bone tissue, leading to a loss of bone density over time.
Q4. Hormones released from the pituitary gland have two different sources. Those that are produced by the neurons of the hypothalamus are released through the _____________, and those produced within the pituitary are released through the _____________.
Correct Answer: (b)
The posterior pituitary (neurohypophysis) stores and releases hormones produced by hypothalamic neurons (such as ADH and oxytocin). The anterior pituitary (adenohypophysis) synthesizes and secretes its own hormones (such as GH and ACTH).
Q5. Alcohol consumption causes a person to urinate more often because alcohol suppresses the release of the hormone
Correct Answer: (c)
Antidiuretic Hormone (ADH) normally acts on the kidneys to reabsorb water back into the blood. Alcohol inhibits ADH secretion from the posterior pituitary; without enough ADH, the kidneys reabsorb less water, leading to the production of larger volumes of dilute urine. (Note: Per the provided answer key, option C is selected).
Q6. Which of the following conditions is unrelated to the production of growth hormone?
Correct Answer: (a)
Blood calcium levels are regulated primarily by parathyroid hormone (PTH) and calcitonin. Growth hormone (GH) is associated with bone and tissue growth, and its imbalances lead to conditions like dwarfism or acromegaly.
Q7. Which of the following is true about lipophilic hormones?
Correct Answer: (b)
Lipophilic hormones do not dissolve well in the aqueous environment of the blood plasma. Therefore, they must travel through the circulatory system bound to specialized transport proteins to remain in solution until they reach their target cells.
Q8. You are designing a pesticide to disrupt the endocrine systems of arthropods without harming mammals. Which of the following substances should be the target of your investigations?
Correct Answer: (c)
Juvenile hormone is a crucial regulator of development, molting, and metamorphosis specifically in insects and other arthropods. Because mammals do not utilize this hormone, targeting it allows for a pesticide that is highly specific to pests with minimal risk to humans.
Q9. Second messengers are activated in response to
Correct Answer: (c)
Hydrophilic (water-soluble) hormones cannot cross the phospholipid bilayer of the cell membrane. To exert their effects, they bind to cell-surface receptors, which then trigger the production of intracellular second messengers (like cAMP) to relay the signal.
Q10. In the Irish Setter, the overall red coat color is controlled by the melanocortin receptor. When this receptor is bound by MSH, dark eumelanin is produced. When bound by an antagonist, red pheomelanin is made. The red color is likely due to a mutation in the
Correct Answer: (b)
If the red coat color is caused by the antagonist successfully out-competing MSH or MSH failing to bind, a mutation that prevents the receptor from binding MSH would leave the receptor constantly available to the antagonist, leading to the permanent production of red pigment.
Q11. Which of the following best describes hormones?
Correct Answer: (b)
Hormones are chemical signaling molecules produced by endocrine glands. Unlike local paracrine signals, hormones are secreted into the bloodstream to reach distant target organs and generally remain active in the body for a longer duration to regulate physiological processes.
Q12. An organ is classified as part of the endocrine system if it
Correct Answer: (d)
The defining functional characteristic of an endocrine organ or gland is that it secretes its chemical products (hormones) directly into the circulatory system (bloodstream) rather than through a duct system.
Q13. You think one of your teammates is using anabolic steroids to build muscle. Continued use of steroids can cause profound changes in cell function because these hormones act
Correct Answer: (a)
Anabolic steroids are synthetic variants of testosterone, a lipophilic steroid hormone. They pass into the cell and bind to intracellular androgen receptors, which then enter the nucleus to upregulate the transcription of genes responsible for muscle protein synthesis.
Q14. You experience a longer period than normal between meals. Your body’s response to this will be to produce
Correct Answer: (b)
During periods of fasting (between meals), blood glucose levels drop. The pancreas responds by secreting glucagon, which stimulates the liver to break down glycogen into glucose and release it into the blood, thereby raising blood sugar levels back to homeostatic levels.
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