DSE Biology | Blood Glucose Regulation: Tutor Lesson Plan (negative feedback, the liver, diabetes)

2026-11-02

Tutor lesson-prep guides · Secondary Biology

Students can say insulin lowers blood glucose but cannot say what it does in liver, muscle and fat, so their answers stall at one mark. This lesson fixes each organ action on a raise-and-lower table.

Objectives — By the end students can: (1) state the fasting glucose range and convert units; (2) write the specific actions of insulin and glucagon in liver, muscle and adipose tissue; (3) use negative feedback to explain the return to normal after a meal and during exercise, and name the broken link in diabetes.

01 Prerequisites (3-minute check)

If any of these fails, fix it before the lesson starts.

Skill	Quick check	Pass mark
Hormones	How do hormones differ from nerve impulses?	Hormones travel in blood, slower and longer lasting; nerve impulses are fast and brief
Digestion and absorption	Where is glucose absorbed and which vessel carries it first?	Absorbed in the small intestine, carried by the hepatic portal vein to the liver
Metabolism	How does glycogen differ from glucose?	Glycogen is the polysaccharide store; glucose is the usable monosaccharide

02 Lesson flow (60 minutes)

Time	Stage	Tutor does	Student does
0-5 min	Opening question	Ask why blood glucose returns to normal two hours after a meal	Hands up; say what they remember
5-15 min	Prerequisite check	Three items (hormone properties, absorption route, glycogen)	Written answers, marked aloud
15-37 min	Three-act teaching	Scripts on the normal range, the two opposing hormones, diabetes and broken feedback	After each act, one sentence: which organ does what
37-49 min	Worked question types	Model four questions as stimulus, hormone, target organ, outcome	Copy, then rewrite unaided
49-55 min	Independent practice	Circulate; ask only “does this step raise or lower glucose?”	Do three items and self-mark
55-60 min	Exit check	Collect answers and count errors	Written, no talking

03 Teaching script (read it out)

Scene 1: Act 1: The normal range and why it matters

Fasting blood glucose is about 3.9 to 5.5 mmol/L; Hong Kong laboratory reports sometimes use mg/dL, so multiply by 18, making 3.9 mmol/L about 70.2 mg/dL. Two reasons to keep it stable: the brain relies almost entirely on glucose, so a low value causes dizziness, sweating and eventually unconsciousness; and a high value raises plasma osmotic pressure so water leaves cells, with long-term damage to vessels and kidneys. The aim of this act is to establish that stability has reasons, not to drill numbers. “Maintained within a narrow range” is more accurate than “kept constant”, because it does fluctuate with meals and exercise.

Why must blood glucose be neither too low nor too high? Give one consequence of each.

Scene 2: Act 2: Insulin and glucagon in opposition

Both come from pancreatic islets: beta cells secrete insulin (51 amino acids), alpha cells secrete glucagon (29 amino acids). When glucose rises, insulin rises and acts on three targets: the liver converts glucose to glycogen and reduces gluconeogenesis; muscle takes up glucose and stores it as muscle glycogen for its own use; adipose tissue converts glucose to fat. When glucose falls, glucagon rises and acts mainly on the liver, breaking glycogen down and releasing glucose into the blood, and converting amino acids and glycerol to glucose. Teach one opposing sentence: insulin stores, glucagon releases, both act on the liver, in opposite directions. Adrenaline also raises glucose during stress or exercise, same direction as glucagon but a different trigger. Stores are roughly 100 g in liver and 400 g in muscle; only liver glycogen can be released into the blood, muscle glycogen fuels the muscle itself – a very common exam point.

Why can liver glycogen raise blood glucose while muscle glycogen cannot?

Scene 3: Act 3: Negative feedback and diabetes

Write the loop: glucose rises, insulin rises, cells take up glucose and the liver stores it, glucose falls, back to normal, insulin secretion falls. That is negative feedback, and breaking any step breaks the loop. Type 1 diabetes is destruction of beta cells, so insulin is insufficient: glucose stays high after meals, fat is mobilised producing ketones, hence thirst, frequent urination and weight loss. Type 2 is reduced responsiveness of cells to insulin, so insulin may even be high while the effect is weak. Answers must separate insufficient secretion from insufficient response, because management differs. Hypoglycaemia follows missed meals or excess insulin; glucagon and adrenaline respond, and if that is not enough the student should describe sweating, tremor and confusion.

In type 1 and type 2 diabetes, which link fails? How should the answer separate them?

04 Question types and worked steps

Type	Example	Steps	Answer
Data description	State the normal fasting glucose range and convert it to mg/dL.	1) Write 3.9-5.5 mmol/L; 2) multiply by 18; 3) gives about 70-99 mg/dL; 4) define fasting as at least eight hours without food.	Example: 5.5 mmol/L is about 99 mg/dL.
Mechanism (feedback)	After a meal, how does the body restore normal blood glucose?	1) Stimulus: glucose rises; 2) beta cells secrete insulin; 3) three target actions: liver stores, muscle takes up, fat converts; 4) outcome: glucose falls and insulin secretion decreases.	Example: all four stages are needed for full marks.
Comparison (two diabetes types)	Compare the causes of type 1 and type 2 diabetes.	1) Type 1: beta cell destruction, insufficient insulin; 2) type 2: cell resistance, insufficient response; 3) one feature each such as age or body type; 4) close by noting different management.	Example: one lacks the key, the other has a faulty lock.
Application (exercise)	Why does blood glucose not keep falling during exercise?	1) Muscle glucose use rises; 2) adrenaline and glucagon rise; 3) liver glycogen breakdown and gluconeogenesis; 4) glucose stays within an acceptable range.	Example: release exceeds storage.

Sanity check (teach this): Sanity checks: 3.9 to 5.5 mmol/L times 18 gives 70.2 to 99.0 mg/dL; a student writing “5.5 mg/dL” has not multiplied by 18. Insulin has 51 amino acids and glucagon 29, a difference of 22; the numbers only show they are different proteins, so do not drill them, but do not garble them either. Liver glycogen at about 100 g and muscle at about 400 g are standard reference values, and the point is that only liver glycogen enters the blood. Negative feedback must be written as a loop; “insulin lowers glucose” without the fall in secretion afterwards earns half.

05 Independent practice (3 questions)

Question	Answer	What to watch
State the three actions of insulin in liver, muscle and adipose tissue.	Liver: glucose to glycogen; muscle: uptake and storage as muscle glycogen; adipose: conversion to fat.	Watch for “lowers blood glucose” with no organ action.
Why does blood glucose stay stable during exercise? Name two hormones and their actions.	Glucagon and adrenaline rise, promoting glycogen breakdown and gluconeogenesis, releasing glucose into the blood.	Watch for muscle glycogen described as releasable into blood.
Which link fails in type 1 and in type 2 diabetes?	Type 1: insufficient insulin secretion; type 2: insufficient cell response to insulin.	Watch for both answered as insufficient insulin.

06 Common mistakes and what to say

Mistake	Student writes	Say this
Only “insulin lowers glucose”	Writing that insulin lowers blood glucose so the body stays normal.	“Name the organ actions: liver stores, muscle takes up, fat converts. Missing any one costs marks.”
Feedback written one way	Writing only that rising glucose triggers insulin, never what happens afterwards.	“Feedback is a loop. When glucose falls, secretion must fall too. Half a loop is not feedback.”
Muscle glycogen raising blood glucose	Writing that muscle breaks down muscle glycogen and releases it into blood.	“Muscle glycogen fuels that muscle only; there is no enzyme to release it into blood. The liver does that job.”
Unit conversion error	Writing that fasting glucose is 5.5 mg/dL.	“mmol/L must be multiplied by 18 to give mg/dL. 5.5 mmol/L is about 99 mg/dL, a big difference.”

07 Homework (paper, section and question numbers)

Secondary Biology chapter index: finish the three items here, then compare with the osmoregulation chapter for the same feedback pattern — Practice 1-3 on this page

08 Exit check (last 5 minutes)

Question	Answer	Decision
Give the normal fasting glucose range.	3.9-5.5 mmol/L	Cannot answer: reteach Act 1
Which organ releases glycogen into the blood?	The liver	Cannot answer: reteach Act 2
What does the “feedback” in negative feedback close?	Falling glucose reduces hormone secretion	Cannot answer: reteach Act 3

09 Tutor FAQ

Which year is this for?

S5 Biology in the coordination and response or homeostasis unit; S4 classes that have covered absorption can start, since the hepatic portal vein links directly.

Must students memorise the amino acid counts?

No. “Insulin is larger, glucagon smaller” is enough; the examinable content is targets and directions.

Is there paired practice?

The homework link goes to the biology chapter index; teaching it beside osmoregulation shows two clean examples of negative feedback.

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A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.