Specialised cells - tissue - organs - organ systems/organisms
i think the answer is : A meiosis because The process of meiosis produces unique reproductive cells called gametes, which have half the number of chromosomes as the parent cell. Fertilization, the fusion of haploidgametes from two individuals, restores thediploid condition. Thus, sexually reproducing organisms alternate between haploid anddiploid stages.
Plants give off oxygen (that we breathe)and breathe in our carbon dioxide that we exhale
