False, sex has to do with the reproductive differences, male sex cells travel to female sex sells, and female sex cells generate new organisms, these are universal across all species including plants and even bacteria to a degree. Gender has to do with mating and child rearing activities, and can differ wildly between species. Males may try to attracte female partners, or vice versa. Mating dances, coloration, guarding young or abandoning them, none of these are fixed to a specific sex across all species. Even when certain patterns emerge (Females carrying young or laying eggs) there are always exceptions. Further, some males may adopt female behaviors as a mating strategy in a single species which creates what amounts to a third gender in that species.