Mock Exam 5
VCE Biology Units 3 & 4 | Homeostasis and Regulation
✎ 120 marks total • approximately 150 minutes. Complete ALL questions on paper before opening the Model Answers lesson. Reading time: 15 minutes (recommended). No notes.
SECTION A — MULTIPLE CHOICE (40 marks)
Question 1 (1 mark)
Homeostasis is best defined as:
✎ Circle your answer
A) the maintenance of a relatively stable internal environment within tolerable limits despite external changes
B) the maintenance of an absolutely constant internal environment with no variation at all
C) the complete elimination of internal environmental change
D) the process by which cells communicate with each other via signalling molecules
Question 2 (1 mark)
Which of the following is NOT a component of a negative feedback loop?
✎ Circle your answer
A) receptor/sensor
B) mutation
C) effector
D) control centre / integrator
Question 3 (1 mark)
In a negative feedback loop, the effector response acts to:
✎ Circle your answer
A) amplify the original stimulus
B) permanently alter the set point
C) reverse or counteract the original change, returning the variable towards the set point
D) increase the deviation from the set point
Question 4 (1 mark)
Positive feedback loops differ from negative feedback loops in that positive feedback:
✎ Circle your answer
A) returns the system to its set point
B) is the primary mechanism maintaining everyday homeostasis
C) never occurs in the human body
D) amplifies the initial stimulus/change, moving the variable further from the set point
Question 5 (1 mark)
Which of the following is an example of positive feedback?
✎ Circle your answer
A) oxytocin release intensifying uterine contractions during labour
B) blood glucose regulation by insulin and glucagon
C) thermoregulation by shivering
D) ADH release when blood is dilute
Question 6 (1 mark)
The hypothalamus acts as the control centre for thermoregulation because it:
✎ Circle your answer
A) directly generates heat via muscle contraction
B) contains thermoreceptors, compares core temperature with a set point (approximately 37 degrees Celsius), and coordinates effector responses
C) is located in the skin, where it detects external temperature only
D) only responds to hormonal signals, not neural ones
Question 7 (1 mark)
When core body temperature rises above the set point, which effector response is most appropriate?
✎ Circle your answer
A) vasoconstriction of skin arterioles
B) piloerection (hair erector muscles contract)
C) vasodilation of skin arterioles and increased sweat gland secretion
D) shivering thermogenesis
Question 8 (1 mark)
Shivering thermogenesis generates heat by:
✎ Circle your answer
A) increasing blood flow to the skin surface
B) reducing metabolic rate
C) evaporating sweat from the skin surface
D) involuntary, rapid skeletal muscle contractions that release heat as a by-product of cellular respiration
Question 9 (1 mark)
Vasoconstriction of skin arterioles in response to cold helps conserve heat by:
✎ Circle your answer
A) diverting blood away from the skin surface, reducing heat loss via radiation and convection
B) increasing blood flow to the skin surface
C) increasing sweat gland secretion
D) causing hair to lie flat against the skin
Question 10 (1 mark)
Which of the following is a behavioural (not physiological) thermoregulatory response?
✎ Circle your answer
A) vasodilation
B) putting on extra clothing when cold
C) shivering
D) sweating
Question 11 (1 mark)
Ectotherms differ from endotherms in that ectotherms:
✎ Circle your answer
A) generate most body heat internally via metabolism
B) always maintain a constant body temperature regardless of environment
C) rely mainly on external heat sources and behaviour to regulate body temperature
D) cannot tolerate any environmental temperature change
Question 12 (1 mark)
Compared with hormonal responses, nervous responses are generally:
✎ Circle your answer
A) slower and longer lasting
B) transmitted only via the bloodstream
C) identical in mechanism to hormonal responses
D) faster acting, more localised/specific, and shorter in duration
Question 13 (1 mark)
Hormonal (endocrine) responses, compared with nervous responses, are typically:
✎ Circle your answer
A) slower to initiate but longer lasting, transmitted via the bloodstream to distant target cells
B) faster, transmitted via electrical impulses along neurons
C) restricted to a single target cell
D) always inhibitory in effect
Question 14 (1 mark)
A neurotransmitter released at a synapse acts on:
✎ Circle your answer
A) any cell in the body
B) only cells with the complementary receptor on the immediate postsynaptic membrane
C) only cells in the bloodstream
D) the presynaptic neuron that released it
Question 15 (1 mark)
A hormone released into the bloodstream will only affect:
✎ Circle your answer
A) all body cells equally, regardless of receptors
B) only the endocrine gland that secreted it
C) target cells possessing specific complementary receptors for that hormone
D) no cells until it reaches the brain
Question 16 (1 mark)
The reflex arc pathway for a withdrawal reflex, in correct order, is:
✎ Circle your answer
A) effector then receptor then sensory neuron then motor neuron
B) motor neuron then receptor then effector
C) receptor then effector then sensory neuron
D) receptor then sensory neuron then interneuron (spinal cord) then motor neuron then effector
Question 17 (1 mark)
Blood glucose concentration is regulated primarily by which two antagonistic hormones?
✎ Circle your answer
A) insulin and glucagon
B) ADH and aldosterone
C) oestrogen and testosterone
D) adrenaline and cortisol
Question 18 (1 mark)
Insulin is secreted by:
✎ Circle your answer
A) alpha cells of the pancreatic islets, in response to low blood glucose
B) beta cells of the pancreatic islets, in response to high blood glucose
C) the liver, in response to low blood glucose
D) the adrenal cortex, in response to stress
Question 19 (1 mark)
Insulin lowers blood glucose concentration by promoting:
✎ Circle your answer
A) glycogenolysis in the liver
B) gluconeogenesis
C) glucose uptake into body cells and conversion of glucose to glycogen (glycogenesis)
D) breakdown of fats to glucose
Question 20 (1 mark)
Glucagon, secreted by alpha cells in response to low blood glucose, acts on the liver to:
✎ Circle your answer
A) increase glycogenesis
B) increase insulin secretion
C) decrease blood glucose further
D) stimulate glycogenolysis and gluconeogenesis, releasing glucose into the blood
Question 21 (1 mark)
Blood glucose regulation is an example of a:
✎ Circle your answer
A) negative feedback loop involving antagonistic hormones
B) positive feedback loop
C) purely nervous reflex with no hormonal involvement
D) one-way, non-regulated pathway
Question 22 (1 mark)
Type 1 diabetes mellitus results from:
✎ Circle your answer
A) target cell insulin receptors becoming unresponsive (insulin resistance)
B) autoimmune destruction of insulin-secreting beta cells, leading to little or no insulin production
C) excess glucagon secretion only
D) overproduction of insulin
Question 23 (1 mark)
Type 2 diabetes mellitus is characterised by:
✎ Circle your answer
A) complete absence of beta cells from birth
B) autoimmune destruction of alpha cells
C) insulin resistance in target cells and/or relatively insufficient insulin secretion, often linked to lifestyle factors
D) excessive glucagon receptor sensitivity in the pancreas
Question 24 (1 mark)
After a meal, which sequence correctly describes the response to rising blood glucose?
✎ Circle your answer
A) rising glucose detected by alpha cells then glucagon released then blood glucose rises further
B) falling glucose then insulin released then blood glucose rises
C) rising glucose then ADH released then blood glucose falls
D) rising glucose detected by beta cells then insulin released then glucose uptake by cells increases then blood glucose falls
Question 25 (1 mark)
Osmoregulation refers to the control of:
✎ Circle your answer
A) water and solute (osmotic) balance in body fluids
B) body temperature
C) blood glucose concentration
D) blood pH only
Question 26 (1 mark)
The functional unit of the kidney responsible for filtration and reabsorption is the:
✎ Circle your answer
A) ureter
B) nephron
C) bladder
D) renal pelvis
Question 27 (1 mark)
Filtration of blood plasma occurs at the:
✎ Circle your answer
A) loop of Henle
B) collecting duct
C) glomerulus (into Bowman’s capsule)
D) ureter
Question 28 (1 mark)
The loop of Henle’s countercurrent multiplier mechanism is important because it:
✎ Circle your answer
A) filters blood cells out of urine
B) produces insulin
C) has no role in water reabsorption
D) establishes a concentration (osmotic) gradient in the renal medulla, enabling production of concentrated urine
Question 29 (1 mark)
Antidiuretic hormone (ADH) is released by the posterior pituitary in response to:
✎ Circle your answer
A) high blood osmolality (concentrated blood), detected by hypothalamic osmoreceptors
B) low blood osmolality (dilute blood)
C) high blood glucose
D) low core body temperature
Question 30 (1 mark)
ADH acts on the kidney to:
✎ Circle your answer
A) decrease permeability of the collecting duct to water, producing dilute urine
B) increase permeability of the distal tubule/collecting duct to water, increasing water reabsorption and producing concentrated urine
C) stop filtration at the glomerulus entirely
D) increase glucose reabsorption only
Question 31 (1 mark)
If a person drinks a large volume of water, blood osmolality falls. This will result in:
✎ Circle your answer
A) increased ADH secretion and concentrated urine
B) increased glucagon secretion
C) decreased ADH secretion, reduced water reabsorption, and dilute, larger-volume urine
D) no change in urine output
Question 32 (1 mark)
Dehydration would be expected to cause:
✎ Circle your answer
A) decreased ADH secretion and dilute urine
B) increased insulin secretion
C) decreased blood osmolality
D) increased ADH secretion, increased water reabsorption, and concentrated, reduced-volume urine
Question 33 (1 mark)
Osmoreceptors that detect blood osmolality are located primarily in the:
✎ Circle your answer
A) hypothalamus
B) skin
C) pancreas
D) adrenal medulla
Question 34 (1 mark)
Fever is best described as:
✎ Circle your answer
A) an uncontrolled, pathological rise in body temperature due to failure of thermoregulation
B) a regulated rise in the hypothalamic set point in response to pyrogens, as part of the immune response
C) always harmful and never adaptive
D) caused only by external heat sources
Question 35 (1 mark)
During the onset of fever, a patient often feels cold and shivers because:
✎ Circle your answer
A) the set point has been lowered
B) sweating has increased
C) actual body temperature is below the newly raised hypothalamic set point, triggering heat-generating/conserving responses
D) actual body temperature is above the new set point
Question 36 (1 mark)
Pyrogens contribute to fever by:
✎ Circle your answer
A) directly killing pathogens through heat alone
B) lowering the hypothalamic set point
C) inhibiting the immune response
D) acting on the hypothalamus to raise the thermoregulatory set point
Question 37 (1 mark)
When a fever ‘breaks’ and the set point returns to normal, the body responds with:
✎ Circle your answer
A) sweating and vasodilation to lose the excess heat
B) shivering and vasoconstriction
C) piloerection
D) increased ADH secretion only
Question 38 (1 mark)
Which statement about homeostatic control systems is correct?
✎ Circle your answer
A) Most homeostatic mechanisms rely on positive feedback to maintain stable conditions
B) Most homeostatic mechanisms rely on negative feedback, while positive feedback is reserved for specific processes such as childbirth or blood clotting
C) Nervous and hormonal systems never interact in homeostatic regulation
D) Set points can never be adjusted under any circumstances
Question 39 (1 mark)
During prolonged exercise, which combination of homeostatic adjustments would be expected?
✎ Circle your answer
A) decreased sweating, decreased heart rate, decreased blood glucose mobilisation
B) increased shivering and vasoconstriction
C) increased sweating (heat loss), vasodilation of skin vessels, and increased glucose mobilisation (via glucagon/adrenaline) for muscle use
D) no change to thermoregulation or blood glucose regulation
Question 40 (1 mark)
Which of the following correctly pairs the variable with its main control mechanism?
✎ Circle your answer
A) blood glucose regulated by ADH; body temperature regulated by insulin; blood osmolality regulated by glucagon
B) blood glucose regulated by oxytocin; body temperature regulated by aldosterone; blood osmolality regulated by adrenaline
C) all three variables are regulated by the same single hormone
D) blood glucose regulated by insulin/glucagon; body temperature regulated by the hypothalamus using nervous and hormonal effectors; blood osmolality regulated by ADH
SECTION B — EXTENDED RESPONSE (80 marks)
Question 1: Thermoregulation as a Negative Feedback Loop
Question 41 (3 marks)
Question 1: Thermoregulation as a Negative Feedback Loop (a)
A person walks outside on a cold winter day and their core body temperature begins to fall below the normal set point (approximately 37 degrees Celsius). Define ‘negative feedback’ and identify the receptor, control centre and effector involved in the response to this drop in temperature.
✎ Write your answer on paper
Question 1: Thermoregulation as a Negative Feedback Loop
Question 42 (3 marks)
Question 1: Thermoregulation as a Negative Feedback Loop (b)
Describe TWO physiological effector responses that occur when core body temperature is too low, and explain how each helps to restore core temperature to the set point.
✎ Write your answer on paper
Question 1: Thermoregulation as a Negative Feedback Loop
Question 43 (2 marks)
Question 1: Thermoregulation as a Negative Feedback Loop (c)
Explain why thermoregulation is described as a ‘dynamic equilibrium’ rather than maintaining body temperature at a perfectly fixed, unchanging value.
✎ Write your answer on paper
Question 2: Blood Glucose Regulation and Diabetes
Question 44 (2 marks)
Question 2: Blood Glucose Regulation and Diabetes (a)
Name the hormone (and the pancreatic cell type that secretes it) responsible for LOWERING blood glucose, and the hormone (and pancreatic cell type) responsible for RAISING blood glucose.
✎ Write your answer on paper
Question 2: Blood Glucose Regulation and Diabetes
Question 45 (3 marks)
Question 2: Blood Glucose Regulation and Diabetes (b)
Describe the mechanism by which insulin lowers blood glucose concentration after a carbohydrate-rich meal.
✎ Write your answer on paper
Question 2: Blood Glucose Regulation and Diabetes
Question 46 (3 marks)
Question 2: Blood Glucose Regulation and Diabetes (c)
Compare Type 1 and Type 2 diabetes mellitus in terms of their underlying cause.
✎ Write your answer on paper
Question 2: Blood Glucose Regulation and Diabetes
Question 47 (2 marks)
Question 2: Blood Glucose Regulation and Diabetes (d)
The table below shows blood glucose concentration (mmol/L) over 3 hours after a meal in a healthy individual and in an individual with untreated Type 1 diabetes.
Time (hours): 0, 1, 2, 3
Healthy individual: 5.0, 7.5, 6.0, 5.0
Untreated Type 1 diabetic: 5.0, 10.5, 12.0, 11.5
Using the data, explain why the blood glucose concentration of the untreated Type 1 diabetic remains elevated instead of returning to normal.
✎ Write your answer on paper
Question 3: The Nephron and Osmoregulation
Question 48 (3 marks)
Question 3: The Nephron and Osmoregulation (a)
Describe the function of each of the following structures in the nephron: the glomerulus/Bowman’s capsule, the loop of Henle, and the collecting duct.
✎ Write your answer on paper
Question 3: The Nephron and Osmoregulation
Question 49 (3 marks)
Question 3: The Nephron and Osmoregulation (b)
Explain how the countercurrent multiplier mechanism of the loop of Henle establishes a concentration gradient in the renal medulla.
✎ Write your answer on paper
Question 3: The Nephron and Osmoregulation
Question 50 (3 marks)
Question 3: The Nephron and Osmoregulation (c)
Describe the role of ADH in regulating water reabsorption, including where it is produced/released and how it acts on the kidney.
✎ Write your answer on paper
Question 3: The Nephron and Osmoregulation
Question 51 (3 marks)
Question 3: The Nephron and Osmoregulation (d)
A patient is severely dehydrated after several hours of strenuous exercise in hot weather without adequate fluid intake. Predict and explain the changes that would occur to (i) ADH secretion, (ii) collecting duct permeability to water, and (iii) urine concentration and volume.
✎ Write your answer on paper
Question 4: Nervous vs Hormonal Regulation
Question 52 (6 marks)
Question 4: Nervous vs Hormonal Regulation
Compare nervous and hormonal (endocrine) regulation of the body in terms of (i) speed of onset, (ii) duration of effect, and (iii) specificity of the target reached. Provide one named example of a nervous response and one named example of a hormonal response in the human body.
✎ Write your answer on paper
Question 5: Fever as a Regulated Response
Question 53 (3 marks)
Question 5: Fever as a Regulated Response (a)
Explain how pyrogens change the hypothalamic set point during infection, and describe the body’s response during the initial (‘chill’) phase of a fever.
✎ Write your answer on paper
Question 5: Fever as a Regulated Response
Question 54 (3 marks)
Question 5: Fever as a Regulated Response (b)
Explain why fever, despite causing discomfort, can be an adaptive/beneficial response during infection, and outline what happens physiologically as the fever ‘breaks’.
✎ Write your answer on paper
Question 6: Positive Feedback in the Human Body
Question 55 (5 marks)
Question 6: Positive Feedback in the Human Body
Using TWO named examples (childbirth/oxytocin and the blood clotting cascade), explain how positive feedback mechanisms amplify a response, and explain why positive feedback loops must eventually be terminated rather than continuing indefinitely.
✎ Write your answer on paper
Question 7: ADH and Urine Osmolality (Data Analysis)
Question 56 (3 marks)
Question 7: ADH and Urine Osmolality (Data Analysis) (a)
A study measured plasma osmolality and plasma ADH concentration in a volunteer over 8 hours: for the first 4 hours the volunteer was deprived of water (plasma osmolality rose from 285 to 300 mOsm/kg, and plasma ADH rose from 1 to 6 pg/mL); the volunteer then drank 1 litre of water over the next 4 hours (plasma osmolality fell back to 286 mOsm/kg, and plasma ADH fell to 1 pg/mL). Describe the relationship shown between plasma osmolality and plasma ADH concentration in this data.
✎ Write your answer on paper
Question 7: ADH and Urine Osmolality (Data Analysis)
Question 57 (3 marks)
Question 7: ADH and Urine Osmolality (Data Analysis) (b)
Explain the physiological mechanism responsible for the relationship described in part (a).
✎ Write your answer on paper
Question 7: ADH and Urine Osmolality (Data Analysis)
Question 58 (3 marks)
Question 7: ADH and Urine Osmolality (Data Analysis) (c)
Predict the effect on urine volume and urine concentration at the 4-hour point (peak plasma osmolality/ADH), with reasoning.
✎ Write your answer on paper
Question 8: Blood Glucose and Insulin After a Meal (Data Analysis)
Question 59 (2 marks)
Question 8: Blood Glucose and Insulin After a Meal (Data Analysis) (a)
The table below shows blood glucose and insulin concentration in a healthy individual following a meal.
Time (minutes): 0, 30, 60, 90, 120
Blood glucose (mmol/L): 5.0, 7.8, 6.5, 5.4, 5.0
Insulin (mU/L): 8, 15, 40, 25, 10
Identify the time of peak blood glucose and the time of peak insulin concentration, and describe the time lag between them.
✎ Write your answer on paper
Question 8: Blood Glucose and Insulin After a Meal (Data Analysis)
Question 60 (3 marks)
Question 8: Blood Glucose and Insulin After a Meal (Data Analysis) (b)
Explain the negative feedback relationship evident in this data.
✎ Write your answer on paper
Question 8: Blood Glucose and Insulin After a Meal (Data Analysis)
Question 61 (3 marks)
Question 8: Blood Glucose and Insulin After a Meal (Data Analysis) (c)
Predict and explain how this data would likely differ in an individual with Type 2 diabetes (insulin resistance), with reference to both the blood glucose and insulin curves.
✎ Write your answer on paper
Question 9: Integration by the Hypothalamus
Question 62 (4 marks)
Question 9: Integration by the Hypothalamus
Using one example, explain how the hypothalamus integrates both nervous and hormonal (endocrine) pathways to maintain homeostasis.
✎ Write your answer on paper
Question 10: Heat Stroke Case Study
Question 63 (3 marks)
Question 10: Heat Stroke Case Study (a)
A marathon runner collapses during a race in extreme heat and high humidity. On examination, their core temperature is 41 degrees Celsius, their skin is hot and dry (not sweating), and they are confused. Explain, in terms of thermoregulatory feedback, why the runner’s cooling mechanisms have failed.
✎ Write your answer on paper
Question 10: Heat Stroke Case Study
Question 64 (3 marks)
Question 10: Heat Stroke Case Study (b)
Suggest and justify TWO appropriate emergency interventions for this runner.
✎ Write your answer on paper
Question 11: Homeostasis and Dynamic Equilibrium
Question 65 (3 marks)
Question 11: Homeostasis and Dynamic Equilibrium
Explain why homeostasis is described as a ‘dynamic equilibrium’ rather than a static, unchanging state, using blood glucose regulation as an example.
✎ Write your answer on paper
Question 12: Exercise Physiology and Multiple Homeostatic Systems
Question 66 (2 marks)
Question 12: Exercise Physiology and Multiple Homeostatic Systems (a)
Besides body temperature, identify TWO other homeostatic variables that are affected during vigorous exercise.
✎ Write your answer on paper
Question 12: Exercise Physiology and Multiple Homeostatic Systems
Question 67 (1 mark)
Question 12: Exercise Physiology and Multiple Homeostatic Systems (b)
State one hormone (other than insulin or glucagon) involved in the physiological stress/exercise response, and briefly state its general effect.
✎ Write your answer on paper
✓ Finished? Open the next lesson — Model Answers — to mark your work.
