1. The energy flow takes place via food chain and food web. During the process of energy flow in the ecosystem, plants being the producers absorb sunlight with the help of the chloroplasts and a part of it is transformed into chemical energy n in the process of photosynthesis.
2. This means that they form a kind of cycle. The extinction of one organism can cause a ripple effect that impacts all of the species involved in that food web. This means that one organism would destabilize the whole food web. The extinction of a keystone specie might force all the organisms to adapt, because this specie is one whose presence and activities strongly affect other species. In other cases the ecosystem is the one that adapts to the lack of the organism. The extinction of species with a strong interaction in the food web occur more often that the others that do not have much interaction. In some cases the food web would be affected because some animals would not have a source of food, therefore they would not have energy. That way they would have to find another way to get the food or in extreme cases they could also get extinct. An example is like the one in the picture, if the phytoplankton dies or decreases its number, its consumers would decrease their number as well, eventually the decrease of a very tiny organism would end up to the extinction of a large organism such as the killer whale or elephant seal.
