1.9 Active Transport

• Cells may need to absorb substances that are in short supply (i.e., against the concentration gradient). Cells use active transport to absorb substances across partially permeable membranes against the concentration gradient. Active transport requires from respiration to move substances against a concentration gradient.
• Why does active transport require energy?


  The particles are being absorbed against a concentration gradient
• Cells are able to absorb ions from dilute solutions. For example, root hair cells absorb mineral ions from the dilute solutions in the soil by active transport. Glucose can be absorbed out of the gut and kidney tubules against a large concentration gradient by active transport. People with cystic fibrosis have thick, sticky mucus because the active transport system in their mucus cells is not working properly
• Name a substance that is moved by active transport into plants from the soil solution

  Mineral Ions