Final answer:
In sexual reproduction, the fusion of gametes occurs, creating a zygote with genetic material from both parents, which develops into a new organism.
Step-by-step explanation:
The process that occurs in sexual reproduction is the fusion of gametes. This involves the joining of a sperm and an egg, which can occur either internally within the body of an organism or externally in the environment. The result of this fusion is a zygote, a fertilized egg cell that contains genetic information from both parents. The zygote then undergoes cell division and develops into a new organism. This process allows for genetic variation and is distinct from asexual reproduction mechanisms like fission, budding, or vegetative propagation.