The theory that is demonstrated by this experiment is natural selection.
Basically, only the strongest bacteria survived, and nature decided which of those bacteria were fit enough to get to live and reproduce in the future. Those bacteria that were "willing" and able to fight their way through a huge number of bacteria were the ones who ultimately won.
Lysosomes break down organelles that are no longer useful.
Chromatids are the daughter strands of a duplicated chromosome which are joined by a single centromere
Whereas somatic cells undergo mitosis to proliferate, the germ cells undergo meiosis to produce haploid gametes (the sperm and the egg). ... The development of a new progeny organism is then initiated by the fusion of these gametes at fertilization.