The Principles and Importance of Homeostasis | OCR A-Level Biology B (Advancing Biology) (H422)
The Principles and Importance of Homeostasis
- 54 questions
- 4 subtopics
- Biology content, examined on all three papers
- Component 01, Component 02 and Component 03
The Principles and Importance of Homeostasis is examined in all three written papers — the specification states that Components 01, 02 and 03 can each assess content from any of the five modules, so nothing is confined to one paper.
It covers homeostatic principles, normal ranges and feedback, the nervous and hormonal control of heart rate, the control of body temperature and the role of thyroxine and measuring core body temperature, hypothermia and hyperthermia.
Sample questions from The Principles and Importance of Homeostasis
Answer each one closed book first, then open the answer.
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Homeostatic principles, normal ranges and feedback
State the normal core body temperature of a healthy adult.
Show the answer
Core body temperature is normally about 37 °C. -
Homeostatic principles, normal ranges and feedback
Contrast positive feedback with negative feedback.
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Positive feedback amplifies the original change and drives the factor further from its starting value, whereas negative feedback opposes the change and restores the factor to its set point. -
The nervous and hormonal control of heart rate
What effect does increased sympathetic activity have on the heart, and which neurotransmitter brings it about?
Show the answer
Noradrenaline is released, which increases the frequency at which the sinoatrial node fires and the force of ventricular contraction, so heart rate and cardiac output rise. -
The nervous and hormonal control of heart rate
Where is adrenaline produced, and how does it reach the heart?
Show the answer
It is secreted by the adrenal medulla and carried to the heart dissolved in the blood plasma. -
The control of body temperature and the role of thyroxine
How does vasoconstriction reduce heat loss in cold conditions?
Show the answer
The arterioles supplying the surface capillaries of the skin constrict, so less blood flows near the surface and more is kept deeper in the body, reducing the heat lost by radiation. -
The control of body temperature and the role of thyroxine
Outline the hormonal pathway that leads to the secretion of thyroxine.
Show the answer
The hypothalamus releases thyrotropin-releasing hormone, which stimulates the anterior pituitary to secrete thyroid-stimulating hormone, and this in turn stimulates the thyroid gland to release thyroxine. -
Measuring core body temperature, hypothermia and hyperthermia
State the core temperatures that define a fever and hypothermia in an adult.
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A fever is a core temperature above 38 °C and hypothermia is a core temperature below 35 °C. -
Measuring core body temperature, hypothermia and hyperthermia
Distinguish between heat exhaustion and heat stroke.
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In heat exhaustion the person sweats heavily and has a raised temperature of up to about 40 °C but remains conscious and is still thermoregulating, whereas in heat stroke the core rises above 40 °C, sweating stops, the skin becomes hot and dry and consciousness is impaired.
The 4 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Homeostatic principles, normal ranges and feedback | Recall questions on homeostasis, receptors, coordination centres and effectors, negative feedback, the normal ranges of core temperature, blood pH, fasting blood glucose and blood pressure, and positive feedback through oxytocin in labour. | 13 |
| The nervous and hormonal control of heart rate | Recall questions on what myogenic means, the cardiovascular centre and its sympathetic and parasympathetic outputs, baroreceptor and carbon dioxide responses, and why adrenaline's effect outlasts a nerve impulse. | 12 |
| The control of body temperature and the role of thyroxine | Recall questions on peripheral and central temperature receptors, the hypothalamus, vasodilation, vasoconstriction, sweating and shivering, and thyroxine, its TRH and TSH pathway, negative feedback control and effect on metabolic rate in prolonged cold. | 13 |
| Measuring core body temperature, hypothermia and hyperthermia | Recall questions on oral, tympanic, axillary and rectal temperature measurement, the thresholds for fever and hypothermia, the causes, symptoms and treatment of hypothermia, heat exhaustion and heat stroke, fuel poverty, and judging claims that climate change affects their incidence. | 16 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
OCR A-Level Biology B (Advancing Biology) Active Recall Guide
Every topic, not just this one. 2,895 questions with their answers.