What would happen if you add a cell wall to an animal cell?

Well if you mean animal cells having a rigid cell wall like that of plant cells a few things would happen: The flexibility of cells would decrease significantly as cell walls act as a rigid barrier and hence your body would be reduced in flexibility. read more

Plants have cell walls to give them strength/support and rigidity that they lack from not being animals with external exoskeletons or internal skeletal components of cartilage or bone. Animals would not be as flexible with a cellulose based cell wall on each and everyone of their cells. read more

When placed into an hypertonic solution, animal cells will shrivel up, while plant cells will stay firm thanks to their air-filled vacuole. In a hypotonic solution, the cells will take on water and appear more plump. In an isotonic solution, they'll stay the same. read more

The cell wall provides the cell with protection from all the unfavorable conditions. The cell wall is a rigid boundary that separates the Cytoplasm with the external environment. Without the cell wall, the plant cell will collapse. Uptake of nutrients would be tough and the cell would be without any protection. Hence the plant would eventually die. read more