Homeostasis and Regulation

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Homeostasis and Regulation — Free MYP4 Biology Practice Questions

1QuestionRegulation of Body TemperatureConcept Practice

2 marks~3 minCriterion A

The diagram of human skin below shows several structures involved in thermoregulation. Structure X is a coiled tubular gland located in the dermis, with a duct opening onto the skin surface.

Identify structure X. [1]

Explain how structure X contributes to cooling the body when core temperature rises above the set point. [1]

Solutions

2QuestionRegulation of Body TemperatureAssessment Practice

2 marks~3 minCriterion A

During a marathon in Singapore (relative humidity ≈ 90%), athletes generate substantial metabolic heat. Sweating is the body's primary thermoregulatory response, yet runners in such conditions frequently suffer heat-related illness despite sweating profusely.

Explain why sweating is less effective at removing heat from the body when relative humidity is high. [1]

Discuss one physiological consequence and one practical limitation this poses for marathon athletes competing in tropical environments. [1]

Solutions

3QuestionNegative Feedback MechanismsConcept Practice

2 marks~3 minCriterion D

Closed-loop insulin pump systems continuously monitor blood glucose and automatically deliver insulin or glucagon to maintain target glucose levels in patients with Type 1 diabetes.

Outline how this device replicates a negative feedback mechanism in the human body. [1]

Discuss one ethical issue raised by the widespread use of closed-loop insulin pump technology. [1]

Solutions

4QuestionRegulation of Body TemperatureAssessment Practice

5 marks~8 minCriterion D

During a physiology study, volunteers underwent two trials.

Experiment 1 — Cold exposure ( $5^\circ C$ , 30 min)
Skin temperature:

33.5^\circ C \rightarrow 28.2^\circ C

Core temperature:

37.0^\circ C \rightarrow 36.8^\circ C

Experiment 2 — Vigorous exercise at $20^\circ C$
Skin temperature / Heat loss at 0 min:

30.5^\circ C

80\ \text{W}

Skin temperature / Heat loss at 10 min:

34.8^\circ C

450\ \text{W}

Skin temperature / Heat loss at 20 min:

35.2^\circ C

500\ \text{W}

Describe the change in skin temperature during cold exposure and identify the vascular mechanism responsible. [1]

Analyse the Experiment 2 data to explain how vasodilation and one additional mechanism together account for the observed increase in heat loss. [2]

Evaluate the hypothesis: "Vasodilation is the primary mechanism for heat loss during exercise, while vasoconstriction is the primary mechanism for heat conservation during cold exposure." Use evidence from both experiments and consider whether the hypothesis provides a complete account of thermoregulation. [2]

Solutions

5QuestionRegulation of Body TemperatureAssessment Practice

7 marks~11 minCriterion C

A person exercises in a

35^\circ\text{C}

environment for 30 minutes. Measurements are taken every 5 minutes.

Time (min)	0	5	10	15	20	25	30
Core temperature ( $^\circ\text{C}$ )	37.0	37.2	37.5	37.8	38.0	38.1	38.1
Skin temperature ( $^\circ\text{C}$ )	33.0	33.5	34.0	34.2	34.3	34.3	34.2
Sweat rate (mL/min)	0	5	10	14	16	12	8

Describe the trend in core body temperature over the 30-minute period and explain the role of negative feedback in the response observed. [2]

Compare the changes in skin temperature and sweat rate between 0 and 20 minutes, and explain how these changes work together to regulate core temperature. [2]

Between 20 and 30 minutes, sweat rate falls from 16 mL/min to 8 mL/min while core temperature remains at

38.1^\circ\text{C}

. Analyse what this pattern suggests about the effectiveness of the negative feedback mechanism under prolonged heat stress. [3]

Solutions

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