1 and * * * have three membrane penetrating modes, namely: free diffusion, auxiliary diffusion (these two are collectively called passive transportation) and active transportation. The main difference lies in whether the carrier and energy are needed when penetrating the membrane. Gas and water enter and leave the battery through free diffusion. A classic example of assisted diffusion is that glucose enters red blood cells and amino acids are absorbed by small intestine for active transport.

2. Because mature red blood cells are dead cells, they have no mitochondria and cannot provide energy. Glucose enters red blood cells and can only assist diffusion. When glucose enters other cells, it needs both carrier protein and energy.

By the way, endocytosis and exocytosis are transmembrane transport!