301. Match each regulatory system with the direction of its principal corrective action. A Column II entry is used once.
| Column I | Column II |
|---|
| P. Insulin | 1. Raises blood \(\mathrm{Ca^{2+}}\) |
| Q. Glucagon | 2. Lowers elevated blood pressure through vasodilation |
| R. PTH | 3. Lowers blood glucose |
| S. ANF | 4. Raises blood glucose |
ⓐ. P-3, Q-4, R-1, S-2
ⓑ. P-4, Q-3, R-2, S-1
ⓒ. P-3, Q-1, R-4, S-2
ⓓ. P-2, Q-4, R-1, S-3
Correct Answer: P-3, Q-4, R-1, S-2
Explanation: Insulin lowers blood glucose by promoting cellular uptake, utilisation and glycogenesis, giving P-3. Glucagon raises blood glucose through hepatic glycogenolysis and gluconeogenesis, so Q-4 is appropriate. PTH is hypercalcaemic and raises blood \(\mathrm{Ca^{2+}}\) through actions involving bone, kidney and intestine, producing R-1. ANF is released from the atrial wall when pressure rises and promotes vasodilation, contributing to a fall in blood pressure, completing S-2. The completed mapping links each hormone with the regulated variable and the direction of its corrective effect. Source, target and physiological direction provide independent checks on the completed mapping. The complete code follows from four biologically consistent pairings rather than from positional elimination alone.
302. An individual begins with elevated blood glucose, low blood \(\mathrm{Ca^{2+}}\) and elevated blood pressure. Insulin, PTH and ANF are released appropriately. Their target tissues respond normally except that vascular ANF receptors are non-functional. In three graphs plotting each regulated variable against time, which combined trend is most likely?
ⓐ. Blood glucose falls, blood calcium rises and blood pressure falls
ⓑ. Blood glucose rises, blood calcium falls and blood pressure falls
ⓒ. Blood glucose stays high, blood calcium stays low and blood pressure falls
ⓓ. Blood glucose falls, blood calcium rises and blood pressure remains elevated
Correct Answer: Blood glucose falls, blood calcium rises and blood pressure remains elevated
Explanation: Three separate hormone-to-target relations must be followed. Insulin acts on its responsive metabolic targets to increase glucose uptake, use and storage, so the initially high blood-glucose curve tends downward. PTH acts through bone, kidney and intestinal calcium handling, raising the initially low blood \(\mathrm{Ca^{2+}}\); its graph tends upward. Elevated pressure can stimulate ANF release from the atrial wall, but the vascular cells in this case lack functional ANF receptors. The hormone cannot produce its normal vasodilatory response through those targets, so the pressure-lowering influence is impaired and the pressure may remain elevated. Normal secretion does not guarantee a normal response when the relevant target cannot recognise the signal. The pressure trace alone would not reveal whether hormone release or target responsiveness had failed; the supplied receptor finding locates the interrupted step. The three curves thus separate intact glucose and calcium regulation from a specified receptor-level failure in pressure control.
303. After a carbohydrate-rich meal, insulin secretion rises normally, but insulin receptors on major target cells are blocked. Glucagon secretion remains possible. Which outcome is most likely?
ⓐ. Rapid correction of blood glucose through normal insulin action
ⓑ. Persistent hyperglycaemia follows loss of the glucose-lowering arm
ⓒ. Immediate fall in blood calcium through thyrocalcitonin action
ⓓ. Increased renal water conservation through blocked insulin receptors
Correct Answer: Persistent hyperglycaemia follows loss of the glucose-lowering arm
Explanation: Insulin is present, but blocked receptors prevent hepatocytes, adipocytes and other responsive cells from recognising the hormone effectively. Glucose uptake, utilisation and glycogenesis accordingly fail to rise normally after the meal. The glucose-lowering branch of pancreatic regulation is impaired, while the opposing glucagon pathway remains available. Blood glucose is therefore likely to remain elevated for longer than normal. The defect lies in target responsiveness rather than insulin secretion. Calcium regulation and renal water conservation involve different hormones and do not explain the post-meal glucose pattern. Following the pathway downstream from the altered step identifies the earliest affected response and any later consequence. Locating the defect at synthesis, transport, receptor recognition or target response determines which parts of the pathway remain functional. At the relevant step in the sequence, the outcome is predicted by separating the damaged endocrine link from neighbouring pathways that are explicitly described as functional.
304. Assertion: Opposing hormonal effects can stabilise a regulated physiological variable.
Reason: Insulin lowers blood glucose while glucagon raises it, and PTH raises blood calcium while thyrocalcitonin lowers it.
ⓐ. Both Assertion and Reason are true, and Reason correctly explains Assertion
ⓑ. Both Assertion and Reason are true, but Reason does not explain the Assertion
ⓒ. Assertion is true, but Reason is false
ⓓ. Assertion is false, but Reason is true
Correct Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion
Explanation: The assertion is true since homeostasis often depends on signals capable of correcting deviations in opposite directions. Insulin and glucagon form an antagonistic pair for blood-glucose regulation. Insulin favours uptake and storage, whereas glucagon favours hepatic glucose release. PTH and thyrocalcitonin similarly act in opposing directions on blood calcium. The reason supplies two valid examples of the principle stated in the assertion and explains how hormonal antagonism helps prevent prolonged deviation of a regulated variable. Both statements are true, and the reason has a direct explanatory relationship with the assertion. Both truth values must be judged independently before the explanatory link between the statements is tested. On comparing the stated claims, the conclusion depends on both factual accuracy and the direction of the biological relationship between the statements.
305. Compare the growth-hormone profiles.
| Row | Hormonal condition | Life stage | Expected disorder |
|---|
| P | GH excess | Growing period | Gigantism |
| Q | GH deficiency | Growing period | Pituitary dwarfism |
| R | GH excess | Adulthood | Gigantism |
The row requiring correction is:
ⓐ. P
ⓑ. Q
ⓒ. R
ⓓ. P and Q
Correct Answer: R
Explanation: Row P correctly links excessive GH during the growing period with gigantism. Row Q correctly links deficient GH during growth with pituitary dwarfism. Row R contains the error. Excessive GH after major body growth is complete produces acromegaly rather than gigantism. Adult tissues remain responsive, but the manifestation shifts toward progressive enlargement and disfigurement of structures such as the face. The table demonstrates that diagnosis requires both the direction of GH abnormality and the life stage at which it occurs. Hormone concentration alone does not distinguish all three growth disorders. The comparison is resolved by combining all reported variables and identifying the row that fits the endocrine mechanism. Across all listed entries, the complete row pattern must be interpreted rather than a single cell read in isolation.
306. Three individuals show the following findings.
Case P: enlarged thyroid, protruding eyeballs, increased basal metabolic rate and weight loss.
Case Q: excessive urinary water loss and dehydration after impaired ADH release.
Case R: prolonged hyperglycaemia, glycosuria and increased ketone bodies.
The correct identification is:
ⓐ. P diabetes mellitus, Q Graves’ disease, R diabetes insipidus
ⓑ. P Graves’ disease, Q diabetes insipidus, R diabetes mellitus
ⓒ. P iodine-deficiency goitre, Q Addison’s disease, R acromegaly
ⓓ. P cretinism, Q diabetes mellitus, R Graves’ disease
Correct Answer: P Graves’ disease, Q diabetes insipidus, R diabetes mellitus
Explanation: Case P combines thyroid enlargement with exophthalmos, increased basal metabolic rate and weight loss, identifying Graves’ disease. Case Q describes failure of ADH-dependent renal water conservation, producing excessive urination and dehydration; this is diabetes insipidus. Case R centres on deficient insulin action and prolonged hyperglycaemia, with glycosuria and ketone-body formation, identifying diabetes mellitus. The three disorders affect different regulated variables: thyroid metabolism, water balance and glucose homeostasis. Their similar endocrine origin does not make their hormones, target tissues or manifestations interchangeable. The relevant mechanism explains both the observed effect and the selectivity of that effect within the endocrine system. For the specified alteration, the interpretation uses every stated condition while avoiding assumptions about tissues or signals that were not altered.
307. Evaluate the disorder assignments.
| Row | Disorder | Primary endocrine relation |
|---|
| P | Addison’s disease | Adrenal-cortical hyposecretion |
| Q | Graves’ disease | Excessive thyroid activity |
| R | Diabetes insipidus | Impaired ADH synthesis or release |
| S | Acromegaly | Adult growth-hormone deficiency |
The row requiring correction is:
ⓐ. P
ⓑ. Q
ⓒ. R
ⓓ. S
Correct Answer: S
Explanation: Addison’s disease is associated with underproduction of adrenal-cortical hormones, so P is valid. Graves’ disease is a hyperthyroid condition, making Q correct. Diabetes insipidus follows impaired ADH synthesis, release or action and is correctly represented by R. Row S reverses the growth-hormone abnormality. Acromegaly results from excessive GH secretion in adults, not deficiency. Adult GH deficiency does not produce the progressive facial and tissue enlargement characteristic of acromegaly. Correct classification requires the disorder, hormone, secretion direction and life-stage qualifier to agree within the same row. Reading across each row preserves the source, signal, target and direction of physiological response. Cross-row comparison distinguishes a complete biological pattern from a partly correct assignment.
308. Comparable thyroid-hormone deficiency occurs in two situations. In Case P it affects a fetus during maternal hypothyroidism; in Case Q it develops in a non-pregnant adult. Which distinction is most appropriate?
ⓐ. P produces exophthalmic Graves’ disease during fetal life, while Q produces growth-hormone-dependent gigantism
ⓑ. P produces diabetes insipidus through ADH deficiency, while Q produces growth-hormone-dependent acromegaly
ⓒ. P may impair normal growth and neural maturation, while Q may disturb metabolism and menstrual-cycle regularity
ⓓ. P increases fetal basal metabolic rate and neural maturation, while Q causes exophthalmos and weight loss
Correct Answer: P may impair normal growth and neural maturation, while Q may disturb metabolism and menstrual-cycle regularity
Explanation: Thyroid hormones are especially important for fetal growth and maturation of the central neural system. Deficiency during pregnancy can produce severe developmental consequences, including stunted growth and intellectual impairment. In an adult, hypothyroidism more prominently affects metabolic regulation and may make the menstrual cycle irregular. The hormonal direction is similar in both cases, but the physiological stage changes the vulnerable processes and resulting manifestations. Exophthalmos and increased basal metabolic rate indicate hyperthyroidism, while gigantism and acromegaly involve growth-hormone excess rather than thyroid-hormone deficiency. Age and physiological stage accordingly modify the manifestation of the same hormonal deficiency, even though the direction of endocrine change is comparable. The comparison distinguishes hormone availability from target responsiveness, which can fail at different stages of one pathway. Under the selective defect, the unchanged conditions exclude a general endocrine failure and make the specified alteration the decisive variable.
309. Which disorder profile is completely consistent?
| Profile | Hormonal condition | Physiological context | Outcome |
|---|
| P | Maternal hypothyroidism | Fetal development | Cretinism-related manifestations |
| Q | Adult GH excess | After major growth | Gigantism |
| R | Insulin deficiency | Glucose regulation | Diabetes insipidus |
| S | Adrenal-cortical hyposecretion | Carbohydrate metabolism | Graves’ disease |
ⓐ. P
ⓑ. Q
ⓒ. R
ⓓ. S
Correct Answer: P
Explanation: Profile P correctly links maternal hypothyroidism with impaired fetal growth and nervous-system maturation and the manifestations associated with cretinism. Profile Q assigns gigantism to adult GH excess, but the appropriate adult disorder is acromegaly. Profile R links insulin deficiency with diabetes insipidus, although inadequate insulin action produces diabetes mellitus. Profile S correctly identifies adrenal-cortical hyposecretion as a metabolic defect but assigns the thyroid disorder Graves’ disease instead of Addison’s disease. Only P maintains agreement among the endocrine abnormality, physiological context and resulting disorder. Every profile must align the hormonal abnormality, developmental or adult context and expected manifestation; one inconsistent column invalidates the entire row. Every column contributes to the inference, so a partly matching row cannot support the final conclusion. When the pathway is traced, the strongest conclusion accounts for every reported observation without assuming changes in unmeasured pathways.
310. Match each source cell with its hormone and principal target or effect. A Column II entry is used once.
| Column I | Column II |
|---|
| P. Pancreatic \(\beta\)-cell | 1. Erythropoietin acting on blood-forming tissue |
| Q. Leydig cell | 2. Insulin promoting glucose uptake |
| R. Juxtaglomerular kidney cell | 3. Testosterone acting on male reproductive tissues |
| S. Hypothalamic neurosecretory cell producing ADH | 4. Vasopressin acting on distal renal tubules |
ⓐ. P-3, Q-2, R-4, S-1
ⓑ. P-2, Q-4, R-1, S-3
ⓒ. P-1, Q-3, R-2, S-4
ⓓ. P-2, Q-3, R-1, S-4
Correct Answer: P-2, Q-3, R-1, S-4
Explanation: Pancreatic \(\beta\)-cells secrete insulin, which promotes glucose uptake and utilisation, giving P-2. Leydig cells produce testosterone and other androgens that act on male reproductive tissues, so Q-3 is appropriate. Juxtaglomerular kidney cells release erythropoietin, which stimulates erythropoiesis, producing R-1. Hypothalamic neurosecretory cells synthesise ADH, which is stored and released from pars nervosa and acts on distal renal tubules, completing S-4. The mapping integrates source cell, hormone identity and target effect rather than relying only on gland names. A single misplaced entry changes the mapping even when the remaining associations appear familiar. Source, target and physiological direction provide independent checks on the completed mapping. When all pairings are checked, the complete code follows from four biologically consistent pairings rather than from positional elimination alone.
311. Hormone H is a peptide released from pancreatic islet cells. It acts mainly on hepatocytes through a membrane-receptor pathway and increases hepatic glycogenolysis and gluconeogenesis. Hormone H is:
ⓐ. insulin
ⓑ. glucagon
ⓒ. cortisol
ⓓ. thyroxine
Correct Answer: glucagon
Explanation: The source, chemical class, receptor mechanism and metabolic actions all identify glucagon. It is a peptide hormone secreted by pancreatic \(\alpha\)-cells and acts mainly on hepatocytes. As a peptide signal, it uses a membrane-bound receptor and intracellular signalling pathway. Its hepatic actions include stimulation of glycogenolysis and gluconeogenesis, both of which increase blood-glucose concentration. Insulin is also a pancreatic peptide but promotes glucose uptake and glycogenesis. Cortisol is an adrenal steroid, while thyroxine is an iodothyronine with an intracellular-receptor mechanism. The combined evidence supports glucagon rather than a single-clue identification.
312. Study the integrated hormone profiles.
| Row | Hormone | Source | Chemical class and receptor | Principal effect |
|---|
| P | Insulin | Pancreatic \(\beta\)-cell | Peptide acting through a membrane receptor | Lowers blood glucose |
| Q | Cortisol | Adrenal medulla | Steroid acting through an intracellular receptor | Anti-inflammatory action |
| R | Estrogen | Growing ovarian follicle | Peptide acting through a membrane receptor | Uterine development |
| S | ADH | Synthesised in pars nervosa | Peptide acting through a membrane receptor | Renal water conservation |
The completely consistent row is:
ⓐ. P
ⓑ. Q
ⓒ. R
ⓓ. S
Correct Answer: P
Explanation: Row P correctly links insulin with pancreatic \(\beta\)-cells, peptide chemistry, membrane-receptor action and a hypoglycaemic effect. Row Q contains a source error because cortisol arises from the adrenal cortex, not the medulla. Row R correctly gives the ovarian source and uterine effect of estrogen but misclassifies the steroid as a peptide using a membrane receptor. Row S correctly describes ADH chemistry and renal action but assigns synthesis to pars nervosa. ADH is synthesised in hypothalamic neurosecretory cells and only stored and released by pars nervosa. Only P is consistent across all four biological layers. Across all listed entries, the complete row pattern must be interpreted rather than a single cell read in isolation.
313. A hormone enters its target cell, binds a nuclear receptor and alters gene expression. When transcription is experimentally blocked, new protein production and the physiological response decline. The strongest conclusion is:
ⓐ. The hormone normally acts only through an extracellular second messenger
ⓑ. The receptor is unnecessary once the hormone crosses the membrane
ⓒ. The response depends on an intracellular receptor and genome-linked pathway
ⓓ. The hormone acts through a membrane receptor before entering the nucleus
Correct Answer: The response depends on an intracellular receptor and genome-linked pathway
Explanation: Entry into the target cell and binding to a nuclear receptor identify an intracellular-receptor mechanism. The loss of new protein production after transcription is blocked places gene expression between receptor activation and the final physiological response. The hormone-receptor complex normally influences the genome, alters messenger RNA production and changes protein synthesis. The response does not depend primarily on an extracellular second messenger, and receptor binding remains an essential recognition step. The experimental sequence connects chemical entry, intracellular recognition, transcription and protein-dependent action within one genome-linked mechanism. A selective block produces a selective consequence; it does not justify loss of every function performed by the organ. Since the remaining components are stated to be intact, the predicted change should be limited to the disrupted link and its direct downstream consequences. At the relevant step in the sequence, following the pathway downstream from the altered step identifies the earliest affected response and any later consequence.
314. Which symbolic relationship is biologically consistent?
ⓐ. \(\text{high blood glucose}\rightarrow\text{glucagon}\uparrow\rightarrow\text{hepatic glycogenesis}\uparrow\rightarrow\text{blood glucose}\downarrow\)
ⓑ. \(\text{low blood glucose}\rightarrow\text{glucagon}\uparrow\rightarrow\text{hepatic glucose output}\uparrow\rightarrow\text{blood glucose}\uparrow\)
ⓒ. \(\text{low blood calcium}\rightarrow\text{TCT}\uparrow\rightarrow\text{bone demineralisation}\uparrow\rightarrow\text{blood calcium}\uparrow\)
ⓓ. \(\text{high blood pressure}\rightarrow\text{ANF}\downarrow\rightarrow\text{vasoconstriction}\rightarrow\text{blood pressure}\downarrow\)
Correct Answer: \(\text{low blood glucose}\rightarrow\text{glucagon}\uparrow\rightarrow\text{hepatic glucose output}\uparrow\rightarrow\text{blood glucose}\uparrow\)
Explanation: Low blood glucose stimulates glucagon secretion from pancreatic \(\alpha\)-cells. Glucagon acts mainly on the liver, where it promotes glycogenolysis and gluconeogenesis. Both processes increase hepatic glucose output, so glucose enters the circulation and the reduced blood-glucose level rises toward the regulated range. The biologically consistent relation is:
\[
\text{low blood glucose}\rightarrow\text{glucagon}\uparrow\rightarrow\text{hepatic glucose output}\uparrow\rightarrow\text{blood glucose}\uparrow
\]
Each arrow has a defined meaning: the initial disturbance changes hormone secretion, the hormone alters a target-organ process, and that process changes the regulated variable in the corrective direction. This is an antagonistic homeostatic relation with insulin, which favours glucose uptake and glycogenesis when blood glucose is high. The sequence must preserve both the direction of the initiating change and the normal metabolic action of glucagon; reversing either one breaks the regulatory logic.
315. An individual has low cortisol and aldosterone, impaired carbohydrate regulation, weakness, reduced renal sodium and water conservation and low blood-pressure support. Adrenal-medullary catecholamine release during a sudden threat remains functional. The most appropriate interpretation is:
ⓐ. Isolated adrenal-medullary failure producing Graves’ disease
ⓑ. Posterior-pituitary failure producing diabetes mellitus
ⓒ. Thyroid hyperactivity producing Addison’s disease
ⓓ. Adrenal-cortical failure with intact medullary responses
Correct Answer: Adrenal-cortical failure with intact medullary responses
Explanation: Low cortisol and aldosterone indicate failure of the adrenal cortex. Reduced glucocorticoid action explains disturbed carbohydrate regulation and weakness, while reduced mineralocorticoid action weakens renal sodium and water conservation and blood-pressure support. This pattern is consistent with Addison’s disease. The preserved catecholamine response shows that the central adrenal medulla remains functional and can still support rapid fight-or-flight adjustments. The case separates two tissues within one gland and demonstrates that cortical hypofunction does not automatically eliminate every adrenal response. The complete diagnosis is adrenal-cortical failure with relative preservation of medullary activity. The decisive clue is the full biological relationship, not merely the occurrence of a familiar endocrine term. For the specified alteration, the mechanism remains consistent only when the messenger, target and direction of response are all assigned correctly.
316. Use the endocrine map described below. Structure P lies on the dorsal forebrain and secretes melatonin. Structure Q consists of small glands on the posterior thyroid surface and secretes PTH. Structure R is the outer region of a gland above the kidney and secretes steroid hormones. Structure S consists of scattered endocrine cell groups within the pancreas. The correct identification is:
ⓐ. P pineal, Q parathyroids, R adrenal cortex, S pancreatic islets
ⓑ. P pituitary, Q thyroid follicles, R adrenal medulla, S pancreatic ducts
ⓒ. P hypothalamus, Q thymus, R adrenal cortex, S exocrine acini
ⓓ. P pineal, Q pituitary, R thyroid cortex, S seminiferous tubules
Correct Answer: P pineal, Q parathyroids, R adrenal cortex, S pancreatic islets
Explanation: The pineal gland occupies the dorsal forebrain and secretes melatonin, identifying P. Four parathyroid glands occur on the posterior thyroid surface and secrete PTH, identifying Q. The adrenal cortex forms the outer region of each adrenal gland above the kidney and produces steroid hormones, so R is the cortex. Pancreatic islets are scattered endocrine cell groups within the predominantly exocrine pancreas, identifying S. The mapping integrates location, tissue organisation and hormonal output across four distinct endocrine structures rather than relying on a single anatomical clue. The stated qualifier limits the conclusion to the specified hormone, tissue and physiological condition. In this biological context, the decisive clue is the full biological relationship, not merely the occurrence of a familiar endocrine term.
317. Evaluate these statements about endocrine coordination.
I. A hormone affects only cells possessing an appropriate receptor.
II. A multifunctional organ may contain specialised hormone-producing cells.
III. Pars nervosa synthesises oxytocin and ADH before releasing them.
IV. Opposing hormonal actions can contribute to homeostasis.
ⓐ. I and III only
ⓑ. II, III and IV only
ⓒ. I, II and IV only
ⓓ. I, II, III and IV
Correct Answer: I, II and IV only
Explanation: Statement I expresses the target-tissue principle: receptor possession determines whether a cell can recognise and respond to a hormone. Statement II is supported by endocrine contributions from the heart, kidney, gastrointestinal tract and pancreas, all of which perform additional major functions. Statement III is false because oxytocin and ADH are synthesised in hypothalamic neurosecretory cells and transported to pars nervosa for storage and release. Statement IV is valid, as shown by insulin-glucagon and PTH-thyrocalcitonin antagonism. The valid combination integrates receptor specificity, endocrine organisational diversity, source-release accuracy and homeostatic regulation. The set is established by checking every claim against the relevant source–target–effect pathway. After each claim is checked, the final combination reflects complete biological consistency across the listed statements rather than recognition of one familiar term.
318. An action potential in a hypothalamic neurosecretory cell triggers release of ADH from pars nervosa. ADH then travels through the blood and acts on receptor-bearing distal renal tubules. This pathway best demonstrates that:
ⓐ. neural activity can initiate an endocrine signal that coordinates a distant target
ⓑ. ADH is a neurotransmitter restricted to a single synaptic cleft
ⓒ. the same hypothalamic neuron must directly innervate every renal tubule
ⓓ. pars nervosa synthesises ADH independently of the hypothalamus
Correct Answer: neural activity can initiate an endocrine signal that coordinates a distant target
Explanation: The initiating event is electrical activity in a hypothalamic neuron, but the final communication step is hormonal. ADH is synthesised in hypothalamic neurosecretory cells, transported along their axons and stored and released from pars nervosa. Once released, it enters the circulation and reaches distal renal tubules that possess the appropriate receptors, where it promotes water reabsorption. The renal target does not need a direct axonal connection with the hypothalamic neuron. This sequence shows a true neural-endocrine integration: neuronal activity controls hormone release, and the circulating hormone extends that control to distant cells. Pars nervosa serves as the storage-and-release region rather than the site of ADH synthesis. The pathway combines the speed and precision of neural initiation with the distribution of an endocrine messenger.
319. An invertebrate has a relatively simple endocrine organisation made of scattered secretory cells. These cells release trace, non-nutrient chemicals that act on receptor-bearing targets and coordinate physiological functions. Which conclusion is most accurate?
ⓐ. The chemicals cannot be hormones because the animal lacks numerous vertebrate endocrine glands
ⓑ. The chemicals are nutrients because they arise from scattered cells rather than a separate gland
ⓒ. They qualify as hormonal coordinators despite the simple organisation of the endocrine system
ⓓ. Endocrine coordination is absent because only neural signals can act in invertebrates
Correct Answer: They qualify as hormonal coordinators despite the simple organisation of the endocrine system
Explanation: Relative simplicity of endocrine organisation does not mean absence of chemical coordination. The described signals meet the functional features of hormones: they are non-nutrient chemicals produced in trace amounts, they act as intercellular messengers and their effects depend on responsive target cells. The modern definition does not require every hormone to arise from a large, separate endocrine gland or to occur only in vertebrates with numerous endocrine structures. Scattered hormone-producing cells can still coordinate physiological activity. The invertebrate-vertebrate comparison concerns relative complexity and number of chemical coordinators, not an absolute boundary between hormonal and non-hormonal animals. Combining organisational simplicity with the messenger-based definition supports classification of the chemicals as hormones while preserving the broader observation that vertebrate endocrine coordination commonly involves many chemical signals and organised glands.
320. An endocrine map gives four location assignments: P, pineal gland on the dorsal forebrain; Q, thyroid around the trachea in the neck; R, thymus behind the sternum in the thorax; and S, adrenal gland in the pelvic region beside an ovary. Which correction is required?
ⓐ. P should be moved from the forebrain to the neck
ⓑ. Q should be moved from the neck to the thorax
ⓒ. R should be moved from the thorax to the cranial cavity
ⓓ. S should be placed above a kidney in the abdominal region
Correct Answer: S should be placed above a kidney in the abdominal region
Explanation: The pineal gland is situated on the dorsal side of the forebrain, so P is correctly placed in the cranial region. The thyroid occupies the neck, with its lobes positioned on either side of the trachea, and the thymus lies in the thorax behind the sternum and between the lungs. The adrenal assignment is the inconsistent one. Humans possess a pair of adrenal glands, with one gland located above each kidney in the abdominal region. Ovaries occupy the abdominal-pelvic region, but an adrenal gland is not positioned beside an ovary as part of the pelvic endocrine arrangement. Correcting S restores the body-region relation without disturbing the other three labels. The correction follows from linking each gland to a distinctive anatomical landmark rather than relying only on a superior-to-inferior sequence.
