The presence of these structures in this stage may be a prediction of a common ancestor as these structures are not gills because they do not develop into gills in chicks and humans but being so similar to gill structures in fish at this stage in their embryo suggests that chicks and humans share a common ancestor with fish.
In plants, photosynthesis takes place in chloroplasts, which contain the chlorophyll. Chloroplasts are surrounded by a double membrane and contain a third inner membrane, called the thylakoid membrane, that forms long folds within the organelle.
