Does god know how you would score on an exam?

If god gave you, oh let's say, a math exam, would he know exactly what answers you would give? The bible suggests that god knows all things from beginning to end. If he is truly omniscient, why did he need to test man with the Tree of Knowledge of Good and Evil? He could have made the Garden of Eden without the tree and not interfered with man's free will. Why, then, didn't he? Did he not know that man, completely na�ve about the consequences of disobedience, would be so easily duped by a more knowledgeable creature? Under such cirstances, was god's punishment more than a little harsh? The pain of labor visited upon every generation of woman? The laborious work required to survive off the land, etc.? I am truly curious as to the justifications someone who believes Genesis is a literal accounting might use.