Why are bacteria, fungi and animals referred to different kingdoms?

Because these organisms have some differences. A large group of organisms may share some common characteristics. They are distinguished into the kingdom of living nature. For example – some organisms have a heterotrophic type of diet and are able to move in search of food, sexual partners, to avoid dangers, etc. Such organisms have been isolated into the animal kingdom. Plants are autotrophs in nutrition and have an attached way of life. But there are some common features in these kingdoms. This is the presence of membrane organelles in the structure of cells. Therefore, they belong to the eukaryotic domain.