Final answer:
Sex determination is a distinct process from sexual reproduction, asexual reproduction, and internal fertilization, playing a unique role in initially establishing an individual's sex, usually through mechanisms like chromosome differences.
Step-by-step explanation:
Sex determination is the mechanism, besides sexual reproduction, that establishes the sex of an individual. It is an essential process that occurs through various mechanisms, such as genetic determination where specific chromosomes like the X and Y in humans dictate gender. Sexual reproduction, on the other hand, entails the combination of genetic material from two individuals to produce genetically diverse offspring, a process that begins with fertilization. This can occur externally or internally, with internal fertilization specific to certain species. Asexual reproduction involves one individual producing genetically identical offspring and does not contribute to sex determination. Processes such as fission, budding, and fragmentation enable asexual reproduction, and are distinct from sexuality-based processes.
In contrast, internal fertilization is a process within sexual reproduction where sperm and eggs combine within the female's body, which can also influence the suitability of certain characteristics in offspring but is not a determining factor in establishing sex at the initial stage. Thus, while sexual reproduction, asexual reproduction, and internal fertilization contribute to the life cycle and propagation of species, they do not establish the sex of an individual except for the initial role sexual reproduction plays in the combination of sexually dimorphic chromosomes.