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    it says here that active transport is required to reabsorb sugar and sufficient ions back in to the blood from a nephron. Im not sure why? could someone elaborate please? :-)
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    Concentration gradients.

    The contents of a cell are higher in sugar and ions than the solution passing through the tubule. As such, the concentration gradient favors movement of sugar/ions into the tubule, rather than re-absorption.

    It's like entering a packed car in the Tube during rush hour, (car = cell, station = tubule). Harder to get into a packed car than to leave it.
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    (Original post by Chelsea12345)
    it says here that active transport is required to reabsorb sugar and sufficient ions back in to the blood from a nephron. Im not sure why? could someone elaborate please? :-)
    This is because sugar and ions are already in the blood, and more sugar and ions needs to go into the blood.
    Active transport is the movement of molecules from an area of low concentration to high concentration (against a concentration gradient).
    We need to absorb all of the sugar (glucose) for respiration and energy, and ions for carrying specific functions in the body.
    However only a small amount of ions is needed, otherwise there will be excess ions that wont be used.
 
 
 
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