Not usually. We say 'rise' and 'fall' to describe graphs, but not 'ascend' or 'descend'. These are Latin-based words, and they are a little bit too literary-sounding for this context.

You can use ascend , descend , increase or decrese.. but I think RISE AND FALL are common terms which are used in colloquial English. Bye my friend

Yes, you can use "ascend" and "descend" or "ascending" and "descending" or "ascendant" and "descendent". Other words which may apply are "increase" and "decrease". Here is a link to a Glossary of terminology associated with Graphing. http://en.wikipedia.org/wiki/Glossary_of_graph_theory .