Which of the following statements, A to D, correctly describes the mechanisms of water and mineral ion transport across the root of a dicotyledonous plant?
Inorganic ions move through the apoplast pathway until they reach the endodermis, where the suberised Casparian strip forces them to cross a selectively permeable membrane via carrier proteins.
Water enters root hair cells because the active uptake of mineral ions into the root cortex increases the water potential of the cytoplasm relative to the soil solution.
The vacuolar pathway provides the least resistance to water flow across the root cortex because it bypasses both the tonoplast and plasmodesmata.
Blockage of the symplast pathway by the suberin strip at the endodermis ensures that toxic ions are filtered out before reaching the phloem.
28 exam-style questions on OCR A A Level Biology Transport in plants. Each one has a worked solution and a mark scheme showing where the marks go.