In sexual reproduction, the genetic material of two individuals is combined to produce genetically diverse offspring that differ from their parents. Fertilization and meiosis alternate in sexual life cycles. What happens between these two events depends upon the organism. The process of meiosis, the division of the contents of the nucleus that divides the chromosomes among gametes, reduces the chromosome number by half, while fertilization, the joining of two haploid gametes, restores the diploid condition. There are three main categories of life cycles in eukaryotic organisms: diploid-dominant, haploid-dominant, and alternation of generations
Instead of oxygen a creature would also need nutrients. Simple everyday things like water and food.
Explanation:
Although it is kind of impossible to live without oxygen. There are organisms on the earth who do not need it and can survive. They metabolize hydrogen or methane or a number of other compounds.
