I would say photosynthetic bacteria are the most important, because if they disappeared most of the oxygen in the atmosphere wouldnt be here and complex life like humans wouldnt exist
When fossil fuels are burned they can cause pollution which can cause global warming.
DNA replication occurs in the synthesis stage and is followed by the gap 2 stage
The question is; would a drug that binds irreversibly to these receptors be an effective contraceptive in mammals?, the answer is;Yes; because if the receptors are blocked the sperms will not be able to penetrate the zonal pellucida of the egg. Contraceptives prevents pregnancy by interfering with the normal process of ovulation, fertilization, and implantation.