DP Biology (last assessment 2024)
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11.3 The kidney and osmoregulation

Description

Nature of science:
Curiosity about particular phenomena—investigations were carried out to determine how desert animals prevent water loss in their wastes. (1.5)
Understandings:
  • Animals are either osmoregulators or osmoconformers.
  • The Malpighian tubule system in insects and the kidney carry out osmoregulation and removal of nitrogenous wastes.
  • The composition of blood in the renal artery is different from that in the renal vein.
  • The ultrastructure of the glomerulus and Bowman’s capsule facilitate ultrafiltration.
  • The proximal convoluted tubule selectively reabsorbs useful substances by active transport.
  • The loop of Henle maintains hypertonic conditions in the medulla.
  • ADH controls reabsorption of water in the collecting duct.
  • The length of the loop of Henle is positively correlated with the need for water conservation in animals.
  • The type of nitrogenous waste in animals is correlated with evolutionary history and habitat.
Applications and skills:
  • Application: Consequences of dehydration and overhydration.
  • Application: Treatment of kidney failure by hemodialysis or kidney transplant.
  • Application: Blood cells, glucose, proteins and drugs are detected in urinary tests.
  • Skill: Drawing and labelling a diagram of the human kidney.
  • Skill: Annotation of diagrams of the nephron.
Guidance:
  • ADH will be used in preference to vasopressin.
  • The diagram of the nephron should include glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule; the relationship between the nephron and the collecting duct should be included.
 Utilization:
  • The removal of kidney stones by ultra sound treatment.
Syllabus and cross-curricular links:
Biology
Topic 1.3 Membrane structure
Topic 1.4 Membrane transport

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