In general, the surface of a tree has a harder “feel” than does the surface of a dog. what cell characteristic or cell structure of each organism can be used to explain the difference?

The presence of cell wall in plants.

Explanation:

A plant cell possesses a cell wall, the presence of a cell wall provides rigidity to it. On the other hand, the cell in animals exhibits no cell wall. The animal cells possess a cell membrane that is, also known as the plasma membrane.  

The surface of a tree feels harder in comparison to the surface of a dog is because of the presence of cell wall in plant cells, which is lacking in the cells of a dog. A cell wall refers to a structural layer enveloping certain kinds of cells and is present external to the membrane of the cell. It can be flexible, tough, and rigid as well. It offers the cell with both structural protection and support, and also functions as a filtering mechanism.  

b) the inside picture would look at a very high temperature in a very low ph