Currently, all of life is classified within three overarching domains and six secondary kingdoms. The classifications then go on to Phylum, Class, Order, Family, Genus, Species. Two of the kingdoms, Archaea and Bacteria, consist of prokaryotic organisms. Prokaryotic cells do not have true nuclei or membrane bound organelles. Instead, they have a nucleoid region where they house their DNA. The other domain, Eukarya, consists of eukaryotic organisms. Dissimilar to prokaryotic cells, eukaryotic cells have a true nucleus and membrane bound organelles.
The organisms shown in the picture are flowers and are, therefore, in the Kingdom Plantae. The kingdoms in Eukarya (besides Kingdom Protista) are classified by their modes of nutrition. Organisms in Kingdom Plantae are photosynthetic autotrophs. These organisms have cells with rigid cell walls made of cellulose. Plants have a green appearance because of a pigment called chlorophyll. Chlorophyll not only gives plants a green color but also captures light for the plants to make their “food” (sugars) through photosynthesis. All animals ultimately depend on plants for food.