List I | List II | ||
---|---|---|---|
A | Mesozoic Era | I | Lower invertebrates |
B | Proterozoic Era | II | Fish & Amphibia |
C | Cenozoic Era | III | Birds & Reptiles |
D | Paleozoic Era | IV | Mammals |
Active transport is a type of cellular transport in which molecules (such as glucose, ions, and amino acids) are transferred across a biological membrane to a place where there are already enough of them. As a result, molecules are moved across concentration gradients using chemical energy (for instance, ATP). Root hair cells and the small intestine wall are persistent active transport sites (villi).
There are two types of active transportation mechanisms such as;