The kidney and urea removalEdexcel International A Level Biology: Mind map

Exam questions on The kidney and urea removal

1. A student prepares a longitudinal section of a mammalian kidney and a stained microscope slide of kidney tissue. She labels the main regions so that she can locate the different parts of the nephrons.
   The glomerulus is a knot of capillaries. Explain how the arrangement of the arterioles supplying and draining the glomerulus helps to produce a high hydrostatic pressure in the glomerulus.2 marks
2. A dietitian is advising an athlete who eats a very high-protein diet. Her daily intake of amino acids is much greater than the amount she needs to make new proteins, and her urine contains a large amount of urea.
   Explain why the liver converts ammonia to urea before it is excreted.2 marks
3. A researcher analyses samples taken from a healthy adult. Blood plasma contains protein at about 70 g dm⁻³, glucose at 0.9 g dm⁻³ and urea at 0.3 g dm⁻³. Fluid collected from inside the Bowman's capsule contains no protein, glucose at 0.9 g dm⁻³ and urea at 0.3 g dm⁻³. Blood in the glomerulus has a hydrostatic pressure of 8.0 kPa, the fluid in the Bowman's capsule exerts a pressure of 2.0 kPa, and the plasma proteins exert an osmotic pressure of 3.5 kPa. Both of the last two oppose filtration.
   Explain why the fluid in the Bowman's capsule contains glucose and urea at the same concentrations as the plasma but contains no protein.3 marks