Question

What molecules require active transport across cell membranes?

Answer 1

1. Endocytosis is a process by which cells can take in large particles and deposit them into the cell.  This is accomplished by forming membrane-bound sacs that pinch off from the cell membrane.  

    Endocytosis can be used to bring large particles, such as glucose, into a cell

 2.Exocytosis is very similar to endoxytosis except that it deposits materials from inside the cell on the outside instead of the other way around.  Vesicles are formed in the Golgi Bodies, filled with materials to be sent outside the cell, and then fuse with the cell membrane and release their contents outside of the cell.  

3. sodium potassium pump

     The Sodium-Potassium Pump is a structure known as a cell-membrane pump that uses energy to transport Sodium and Potassium ions in and out of the cell.

Answer 2

The molecules of mineral salts and ions like K$^{+}$  require active transportation accross cell membrane bcoz thier relative concentration is more inside the root hair cell then in the soil. So the move against the concentration gradient.