Scientists believe that photosynthesizing organisms originated in water. Before the earth had an atmosphere, water provided the only protection from the harmful rays of the sun. As the organisms in the water began to produce oxygen and a atmosphere developed, it was possible for land plants to evolve. You have studied photosynthesizing organisms from algae, diatoms and dinoflagellates (Kingdom Protista) to more advanced forms in the Kingdom Planta starting with bryophytes (the most simplistic land plants), then ferns and finally gymnosperms (the most complex group in the plant kingdom we have looked at so far. Trace the progression from one group to another (algae, bryophytes, ferns and gymnosperms). What changes took place from one group to another? What advantages did each progressive group have over the last? Would you classify each as more sucessful than the last?