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9 marksThe Uptake and Transport of Water and Minerals

CAPE Biology Unit 2 · May/June 2026 · Paper 2 · Question 2(c)(ii)

The root endodermis regulates water and nutrient uptake, and uses the Casparian strip, which is composed of suberin and lignin, to block harmful substances. Recent research shows that suberin levels adjust in response to environmental stresses such as salinity and nutrient availability. The results of the research that was undertaken are shown in Figures 7 and 8.

With reference to the data given, explain how changes in suberin levels in the root endodermis allow plants to adapt to environmental stresses such as low salinity, high salinity and nutrient deficiencies. You MUST present your response in complete paragraphs.

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Other parts of this question

  1. 2(a)(i)Name EACH of the following chambers shown in Figure 4.[3 marks]
  2. 2(a)(ii)In the space provided, draw a detailed drawing of the same size and proportion as the heart specimen shown in Figure 4 on page 10.[5 marks]
  3. 2(b)(i)Define the term 'transpiration'.[2 marks]
  4. 2(b)(ii)Using the data given in Figure 5, explain the effect of soil water availability on the transpiration rate of the plants investigated.[6 marks]
  5. 2(b)(iii)Explain how water moves from the soil to Cell 3 in terms of water potential.[3 marks]
  6. 2(c)(i)Outline ONE characteristic of the Casparian strip that allows it to control the movement of water and ions into the xylem of a plant.[2 marks]

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