Q77 - Tracing Endocrine Feedback Loops with Sensitivity-Altering Drugs
A set of experiments on the regulation of hormone secretion and effects of various drugs on the activities of endocrine glands were conducted on rats. Rats were divided to different groups and each group was injected with a hormone or a drug. Some physiological parameters were collected and analysed.
Using the information and data, determine which of the statements are true or which are false.
A. The group of rats injected with the drug that reduces the sensitivity of hypothalamus to cortisol resulted in higher plasma levels of both glucose and insulin than those in the group of rats injected with the drug that reduces the sensitivity of adrenocorticotropic hormone (ACTH) receptors.
B. The group of rats injected with the drug that increases the sensitivity of hypothalamus to thyroxine resulted in higher metabolic rate and body temperature than those in the group of rats injected with the drug that increases the sensitivity of target cells to thyrotropin-releasing hormone (TRH).
C. The group of rats injected with propylthiouracil (which blocks thyroid hormone synthesis) resulted in smaller thyroid gland and body weight than those in the group of rats injected with placebo.
D. The group of rats injected with thyroid stimulating hormone (TSH) had smaller pituitary gland and bigger adrenal glands compared with the group of rats injected with corticotrophin-releasing hormone (CRH).
Question reproduced from IBO 2016, Theoretical Paper B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)