Answer:
There are four elements of transport (i think you already knew that)
Explanation:
The four elements of transport are (i) the way, (ii) the unit of carriage, (iii) the motive power unit, and the terminal. (i) The way. Natural ways are cheap and free, and have no maintenance costs unless we try to improve them artificially. The sea, the air, the rivers, and footpaths are all natural ways.
Active transport is a very important process enabling cells to accumulate molecules or ions from the environment against the concentration gradient. The active transport system most intensively studied is the membrane ATPase of the red blood cell and many other membranes.
Hope this helps
