Biology Deoxygenated blood first enters in _________ part in fishes? Options:A. Sinus venosusB. Right atriumC. Left atriumD. Conus arteriosusView AnswerA. Sinus venosus Continue Reading Previous: _________________ cells of phloem are directly involved in transport of organic solutes?Next: Exposure to low temperature stimulates plants to flower. This is called___________?