Final answer:
Land plants and photosynthetic organisms with chloroplasts derived from cyanobacteria belong to the supergroup Archaeplastida, resulting from a primary endosymbiotic event where a eukaryotic ancestor engulfed cyanobacteria.
Step-by-step explanation:
Land plants and other photosynthetic organisms that have chloroplasts derived from endosymbiotic cyanobacteria belong to the supergroup Archaeplastida. The relationship between these land plants, algae, and other photosynthetic eukaryotes, originates from a process known as primary endosymbiosis, where an ancestral eukaryotic cell engulfed a photosynthetic cyanobacterial cell. This event is hypothesized to have occurred once, leading to the majority of photosynthetic organisms we see today that utilize chlorophyll similar to that found in cyanobacteria to carry out oxygenic photosynthesis.
Due to this symbiotic relationship, the chloroplasts in these organisms have two membranes and contain DNA and ribosomes that closely resemble those of cyanobacteria. It is noteworthy that within the rhizarian Paulinella, a recent and separate endosymbiotic event has led to a different form of photosynthetic machinery, however, this is much less common.