[Solved] The mesiobuccal root is the longest root on maxillary first and second molars. Erotic Plasticity: The degree to which an individual's sex drive can be changed by societal or environmental factors. Sexual Orientation: An inherent or immutable enduring emotional, romantic, or sexual attraction to other people. Refractory Period: A phase right after being stimulated in which a muscle or nerve cannot respond to additional stimulation. Sexual Orientation: An enduring pattern of romantic or sexual attraction to persons of the opposite sex, the same sex, both sexes, or more than one gender.