The short answer
How the body holds temperature, glucose and pH steady — the negative-feedback loop, and the rare positive-feedback exceptions.
Written and checked by GAMSAT tutors — not AI-generated.
Try the reasoning style
We treat forgetting as a failure — a lapse to be patched with reminders and records. Yet a mind that kept everything could not think; it would drown in the undifferentiated noise of every moment it had ever lived. To forget is not so much to lose information as to decide, mostly without our noticing, what was never worth keeping.
The author's argument relies most directly on which unstated assumption?
Pick an option to see how the tutor reasons to the answer — not just whether you were right.
Not quite — the answer is B.
Work backwards from the conclusion: a mind that ‘kept everything’ supposedly ‘could not think.’ That only follows if thinking means leaving most of experience out — so B is the premise the argument quietly rests on. A raises reliability, which the passage never weighs; C contradicts ‘mostly without our noticing’; D smuggles in a claim about intellect the passage never makes. The question rewards finding the hidden premise, not recalling a fact.
Homeostasis is keeping the internal environment stable — temperature, blood glucose, pH, water balance — within tight ranges despite a changing world. Almost every system that does this runs the same control loop, and recognising it is worth easy marks.
The loop
Stimulus (something drifts from the set point) → receptor (senses it) → control centre (compares to the set point) → effector (acts) → response (pushes back toward the set point). Then the loop repeats — constantly nudging the variable back.
Negative vs positive feedback
Negative feedback OPPOSES the change and restores the set point — this is the norm (temperature, glucose, blood pressure). Positive feedback AMPLIFIES the change and is rare — used only when the body wants to push something to completion: childbirth (oxytocin) and blood clotting. If you see runaway amplification, it's positive feedback.
Worked example
After a sugary meal, blood glucose spikes. Trace the negative-feedback response that brings it back down — and what happens later if glucose drops too low.
Check yourself
Which of the following is an example of POSITIVE feedback?
Check yourself
When a blood vessel is cut, each activated clotting factor activates more of the next, so the clot builds faster and faster until the breach is sealed. Which description fits?
Check yourself
Someone whose pancreas cannot release insulin eats a large, sugary meal. Compared with a healthy person, what happens to their blood glucose, and why?
Key takeaways
- Homeostasis = a stable internal environment within narrow ranges.
- Loop: stimulus → receptor → control centre → effector → response.
- Negative feedback opposes change and restores the set point (the norm).
- Positive feedback amplifies change — rare (childbirth, blood clotting).
- Glucose: insulin lowers it, glucagon raises it — an opposing pair.
Practise this with real GAMSAT-style questions
A timed diagnostic, real practice questions with worked explanations, and your first essay marked on our rubric built from ACER's two published criteria.