Answer:
In the given case, the scientist should first look for a cell wall as only cells of the plants possess a cell wall. After that he or she should examine for chloroplasts as animal cells do not possess chloroplasts. And finally, he or she should look for the vacuole, that is, if the vacuole is of small size, then it is most probably be an animal cell, however, if it is large then it is most probably a plant cell.
