[Solved] The formation of the fertilization membrane requires an increase in the availability of A) bicarbonate ions. B) calcium ions. C) hydrogen ions. D) potassium ions. E) sodium ions. Paternity Uncertainty: The impossibility for a male to be absolutely certain that he is the biological father of a child, due to the nature of internal fertilization and gestation in females. Extradyadic Sex: Sexual activity that occurs outside of a committed relationship, often considered a breach of exclusivity. Erotic Plasticity: The degree to which an individual's sex drive and sexual interests can change based on various social, environmental, and situational factors. Cheating: The act of being dishonest, deceitful, or breaking rules to gain an unfair advantage.