You could use template_include
conditionally.
add_filter( 'template_include', 'wpsites_photo_page_template', 99 );
function wpsites_photo_page_template( $template ) {
if ( is_category('33') ) {
$new_template = locate_template( array( 'photo.php' ) );
if ( '' != $new_template ) {
return $new_template ;
}
}
return $template;
}