(a) Fig. 5.1 is a photomicrograph of part of the cortex of a kidney.

1. (a)(i)On Fig. 5.1, use label lines and letters to label: G - the glomerulus L – the lumen of the Bowman's (renal) capsule.[2]
2. (a)(ii)During ultrafiltration, components of blood in the glomerulus with a relative molecular mass greater than 68000 are prevented from passing into the Bowman's capsule. Name the structure that acts as this filtration barrier.[1]
3. (b)The glomerular filtration rate (GFR) is the rate of flow of filtered fluid through the kidneys per unit time. The afferent arterioles supply blood to the glomerulus of each nephron within the kidney and the efferent arterioles take blood away from each glomerulus. The lumen diameters of the afferent and efferent arterioles have a large effect on the GFR. Normally the lumen diameters of the afferent and efferent arterioles are different, but they can change to increase or decrease the normal GFR in response to changing conditions. Complete Table 5.1 to indicate whether the GFR is normal, increased, or decreased for each combination of arteriole diameters shown. The first row has been completed for you. [Table 5.1][2]
4. (c)After leaving the Bowman's capsule, the glomerular filtrate passes through the proximal convoluted tubule, where selective reabsorption occurs. Describe and explain how all of the glucose in the glomerular filtrate is reabsorbed back into the blood.[5]
5. (d)State and explain three features of a proximal convoluted tubule cell that adapt it to its function.[3]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.