You are told that the cells on a microscope slide are plant, animal, or bacterial. you look at them through a microscope and see no membrane-bound organelles. you conclude correctly that the cells:

These cells are eukaryotic plant cells.

Explanation:

Plant eukaryotic cells form the tissues of plants. They are similar to animal cells in that they have many organelles in common, but differ from them because they have cell wall, chloroplasts and vacuoles, appropriate to the way of life of plants. Moreover, in this type of cell it is not possible to visualize membrane-bound organelles due to the presence of the cell wall.

The cell wall or cellulosic wall is exterior to the plasma membrane surrounding the cell. It is a more or less thick wrap, composed of a polysaccharide called cellulose.  Its function is to support the plant, which is why it is also called the skeletal cellulose membrane.

There are pores in the cellulosic walls through which pass very thin cytoplasm bridges called plasmodesmos. Through plasmodesms there is communication between the cytoplasm of neighboring cells.