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IB Biology HL D3.3 Homeostasis Question Bank

Practise IB Biology HL D3.3 by explaining feedback control, blood glucose, thermoregulation, ultrafiltration and ADH responses.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • identify the regulated variable, receptor, control centre and effector in a negative-feedback loop
  • explain insulin and glucagon control of blood glucose and distinguish type 1 from type 2 diabetes
  • predict sweating, vasodilation, vasoconstriction or heat production from a temperature change
  • trace ultrafiltration and selective reabsorption through the glomerulus, Bowman's capsule and PCT
  • explain how the loop of Henle and ADH-controlled aquaporins produce concentrated or dilute urine

Covered syllabus points

D3.3.1—Homeostasis definitionD3.3.2—Negative feedback loopsD3.3.3—Blood glucose regulationD3.3.4—DiabetesD3.3.5—ThermoregulationD3.3.6—Thermoregulation mechanismsD3.3.7 (HL)—Kidney roleD3.3.8 (HL)—Glomerulus, Bowman's capsule, PCTD3.3.9 (HL)—Loop of HenleD3.3.10 (HL)—Osmoregulation by collecting ductsD3.3.11 (HL)—Blood supply changes

D3.3 Homeostasis question 1

[Maximum number: 1]

The dimensions of four structures were measured in the hearts of eleven patients with anorexia and in the same number of control subjects.
(a) Discuss the support provided by the data for the claim that anorexia leads to the breakdown of heart tissue.
(b) In control subjects, blood potassium levels are maintained, through homeostasis, between 3.5 and 4.5 mmol litre −1{ }^{-1}. In patients with anorexia, blood potassium can fall below this level. This is known as hypokalemia. In patients with kidney failure, levels can rise above this range, causing hyperkalemia. The traces show the electrocardiograms (ECGs) of a patient with hypokalemia, a normal subject and a patient with hyperkalemia.

Figure for Question D3.3 Homeostasis question 1 — IB Biology HL

Sometimes hyperkalemia occurs as a body tries to respond to low blood pH . State the normal range of blood pH in the human body.

D3.3 Homeostasis question 2

[Maximum number: 1]

The diagram shows a feedback pathway.

Figure for Question D3.3 Homeostasis question 2 — IB Biology HL

Which sequence is an example of the pathway?

I

II

III

high blood sugar

alpha cells

secretion of insulin

low blood sugar

alpha cells

secretion of glucagon

high blood sugar

beta cells

secretion of glucagon

low blood sugar

beta cells

secretion of insulin

D3.3 Homeostasis question 3

[Maximum number: 7]

Living organisms have mechanisms for preventing or reducing change.

Describe the mechanisms used to keep blood glucose levels within narrow limits in humans.

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