Nature of science:

Curiosity about particular phenomena—investigations were carried out to determine how desert animals prevent water loss in their wastes. (1.5)

• 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.

• 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

• DH 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.