Some species of present day protists contain living

Last updated: 2/3/2023

Some species of present day protists contain living organisms within their cytoplasm Paramecium bursaria are hosts for zoochlorellae photosynthetic protists that live within the cytoplasm of the paramecium The relationship appears to be symbiotic the zoochlorellae gain protection and possibly some essential nutrients from the host cytoplasm and the paramecium host has an available food source when its usual food source is depleted This symbiotic relationship provides support for the theory of endosymbiosis which states that O photosynthetic organisms like today s land plants evolved from photosynthetic bacteria animal like cells evolved from ancestors that were photosynthetic mitochondria and chloroplasts evolved from small prokaryotes living within larger cells heterotrophic organisms could not have evolved before the evolution of photosynthetic organisms