Cell wall - Adds structural support to the cell. Holds the cells together
Cell membrane - Serves as a barrier to the cell and allows more nutrient and molecules to move in and out of the cell without letting things that can harm the cell in.
Outer membrane - Serves the same basic functions a the cell membrane. (Depending on how complicated the class your in is, I would visit this website for more information... https://en.wikipedia.org/wiki/Bacterial_outer_membrane )
Pili - Help the cell move and attach the bacteria to surfaces are other cells.
DNA - Contains the genetic instructions on what the cell can physically do, operate, and reproduce.
Flagellum - Helps the cell move. It kind of acts like a propeller for the cell so that it can move around.
The alveoli are lined with mucus and are surrounded by a network of blood capillaries. They have very thin walls for gases to be absorbed through. An individual air sac is called an alveolus. The layer of moisture in the alveoli allows gases to dissolve so that they can diffuse quickly.
The number of consumers increases
Some ways to describe why the beaks are different from the birds that will only eat nectar and the birds that eat fruit are; the nectar eating birds have longer and thinner beaks. The beaks of the fruit and seed eating birds have have shorter and thicker beaks.