Answer
In the endosymbiotic theory, one bacterium would have ingested a smaller bacterium, meaning the smaller bacteria was taken into the body of the larger bacteria. Once the smaller bacterium was inside, the larger bacterium would not have digested it, meaning it would not have released enzymes to break down the smaller bacterium. Therefore, "ingested but not digested" means that the smaller bacterium was taken into the larger bacterium but was not destroyed.
Work Step by Step
In the endosymbiotic theory, one bacterium would have ingested a smaller bacterium, meaning the smaller bacteria was taken into the body of the larger bacteria. Once the smaller bacterium was inside, the larger bacterium would not have digested it, meaning it would not have released enzymes to break down the smaller bacterium. Therefore, "ingested but not digested" means that the smaller bacterium was taken into the larger bacterium but was not destroyed.
