control of blood water potential

Alport syndrome (AS) is an inherited disorder that affects kidney glomeruli of both men and women. Affected individuals have proteinuria (high quantities of protein in their urine). Suggest how AS could cause proteinuria. (2)

• affects/damages basement membrane

• so proteins can pass into glomerular filtrate

Scientists investigated the relationship between the thickness of the kidney medulla of different species of mammals and the concentration of their urine. The graph shows their results (a direct positive correlation). Explain the pattern shown by the results in the graph above. (3)

• thicker medulla means longer loop of Henle

• longer loop means increased sodium ion concentration in medulla

• water potential gradient maintained so more water moved absorbed from the loop of Henle by osmosis

Creatinine is a breakdown product of creatine found in muscle tissues. Apart from age and gender, give two factors that could affect the concentration of creatinine in the blood. (2)

• muscle/body mass

• ethnicity

• kidney disease

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