Question

why do you think all organisms (prokaryotes and eukaryotes) can use glycolysis but not all organisms use the kreb's cycle and etc (only eukaryotes do)?

Answer 1

It is simply because glycolysis contains enzyme systems in the cyotplasm. On the other hand, krebs cycle contains enzymes in the mitochondria. There is no Krebs cycle if the organism does not have mitochondria. Take note that not all organisms have mitochondria.