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Edexcel IGCSE Biology 2.78B Dialysis

Edexcel IGCSE Biology 2.78B Dialysis
Edexcel IGCSE Biology syllabusBiology 4BI1First assessment 2019

Practise explaining how ADH changes water reabsorption, urine volume and urine concentration after dehydration or drinking.

How this is tested

  • explain how dehydration leads to more ADH and a more permeable collecting duct
  • predict urine volume, colour or urea concentration from water intake and sweating data
  • describe dialyser features that increase urea removal,

Question 3(b)(iii)

[Maximum number: 4]

Diagram 1 shows the human urinary system with some structures labelled.

Diagram 1

Diagram 1

Diagram 2 shows a nephron with some parts labelled.

Diagram 2

Diagram 2

The table gives the concentrations of glucose and urea in the filtrate at parts W, X, Y and Z .

Table for Question 3(b)(iii) — Edexcel IGCSE Biology

The concentrations in the table are for a person who has drunk water and is not dehydrated.

Explain why the concentration of urea at Z would be different for a person who is severely dehydrated.