WHAT are the functions of the fallowing types of cell junctions?

Unfortunately, I am unaware of the first two types of cell junctions, but I can help you with the remaining three.

Tight junctions are connections between cells that are not really connections. They provide a seal so that fluids from one don't exit and go into the other. These are found in stomach cells. It'd be bad if the stomach acids leaked and went into our small intestines, so the lining of the stomach have cells with stated junctions that prevent leaking.

Gap junctions perform the opposite. They are used to transport rather large materials from one cell to another without having to worry about it getting past the cell membrane and other protective layers.

Plasmodesmata are present in plant cells, which have strong resistant cell walls composed of cellulose. Because of these walls, even adjacent plant cells are unable to communicate with each other. Plasmodesmata serve as a channel from one to the other, acting as a form of communication.

desmosomes are like disk-shaped adherens junctions.

The function is cell-cell adhesion, but its mainly for tissues that experience mechanical stress like the heart and epithelial layers of the skin.

adherens junctions work with cadherins to bind cells to neighbouring cells with Ca2+ dependent linkages. Occur as 'belts'.

Gap junctions are composed of 'connexins' which are integral membrane proteins that facillitate the exchange of information between cells in close proximity.
not sure about the other two.