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2 marksThe Kidney, Excretion and Osmoregulation

CAPE Biology Unit 2 · May/June 2025 · Paper 2 · Question 2(b)(iv)

Figure 3 is a photomicrograph of a cross-section of the proximal convoluted tubule of a nephron in the kidney.

The convoluted tubule shown in Figure 3 is adapted for reabsorption. Outline ONE adaptation of the epithelial cells of the proximal convoluted tubule that allows the tubule to carry out its function of reabsorption.

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Other parts of this question

  1. 2(a)(i)Define the term 'myogenic'.[2 marks]
  2. 2(a)(ii)State ONE role of EACH of the following structures in the heart during the initiation and coordination of the cardiac cycle: Sinoatrial node (SAN), Purkyne…[2 marks]
  3. 2(a)(iii)Use the information in Figure 2 to calculate the heart rate in beats per minute.[2 marks]
  4. 2(a)(iv)Using the information in Figure 2, state ONE reason why Point X indicates the opening of the semilunar valve of the aorta.[1 mark]
  5. 2(a)(v)Label the graph in Figure 2 using an arrow and the letter Y to show when the atrioventricular valves open.[1 mark]
  6. 2(a)(vi)Label the graph in Figure 2 using a double-ended arrow and the letter Z to show when the ventricle is being filled with blood.[1 mark]
  7. 2(b)(i)Define the term 'excretion'.[2 marks]
  8. 2(b)(ii)Outline ONE reason why the main nitrogenous waste product excreted by mammals is urea rather than ammonia.[2 marks]
  9. 2(b)(iii)Draw a diagram of the bordered structure shown in Figure 3 in the space provided below.[5 marks]
  10. 2(c)(i)State ONE reason why there is a difference between the quantity of water in the glomerular filtrate and the quantity of water in the urine.[1 mark]
  11. 2(c)(ii)Explain the differences in the concentration of EACH of the following substances in blood plasma, glomerular filtrate and urine as shown in Table 2. You MUST…[9 marks]

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