Science fiction text like the one studied "Planet of the Apes" has typical and common elements such as conventional characters, setting, themes and plots. These are explored in Planet of the Apes and in numerous different ways across a number of different texts which helps to classify science fiction genre.
Conventional characters in Planet of the Apes would be that the good guys are not considered to be as powerful as the bad guys. The good characters "Taylor" and his crew start out with nothing apart from their emergency boxes and their wrecked space ship. But the bad characters like for example "Dr Zeis" his henchmen are given every possible weapon to hunt down the cavemen, for example they are given horses, nets and ammunition.
Conventional characters are also explored though the bad characters are usually of a larger superiority than the good guys. For example "Dr Zeis" and his three other colleges are treated like government officials, in the case of them giving "Taylor" a fair trial they have the privilege of sitting at a table whereas "Taylor" had to stand naked.
A frequent setting for most science fiction texts would be that they are set in laboratories and isolated locations where people are not allowed to go. An example for a setting in a laboratory would be when Taylor had been captured and was put in a cage, then to be dissected and examined.
An isolated location in this case would be the "Forbidden Zone" the characters are constantly told not to go past a certain point marked out by the X marked posts. They seem to not go past the "Forbidden Zone" because a higher power tells them that if they do, then they'll die. But since they are told...