What process describes the creation of a new organism by the physical union of male and female gametes?

The correct answer is fertilisation, which refers to the process where male and female gametes unite to form a new organism. In sexual reproduction, this fusion occurs typically in animals and plants, where the male gamete (sperm) combines with the female gamete (egg) to create a zygote. This zygote will then undergo cell division and development to eventually become a new individual.

Fertilisation is crucial as it combines the genetic material from both parents, leading to offspring with a mix of traits from both, ensuring genetic diversity. This process is fundamental in the life cycles of many organisms, enabling reproduction and continuation of species.

In contrast, pollination involves the transfer of pollen from male to female reproductive structures, which can lead to fertilisation but is not the union itself. Conjugation refers to a method of genetic exchange in certain microorganisms, often involving direct transfer of DNA rather than the formation of gametes. Genetic variation describes the differences in DNA sequences among individuals in a population, which can arise from processes like fertilisation, but it is not a process of creating a new organism.