there are two types of endoplasmic reticulum, rough endoplasmic reticulum and smooth endoplasmic reticulum, the rough endoplasmic reticulum is the site of protein manufacture( because it has ribosomes) whereas the smooth endoplasmic reticulum manufactures fat molecules or lipids. these lipids helps in membrane biogenesis, which is the process of formation of plasma membrane. the main function of the endoplasmic reticulum is that it serves as channel for transportation of proteins etc between various cells or a cell organelle and another cell. In the liver, detoxification of poisons take place due to the help of smooth endoplasmic reticulum.
D) because those birds are scavengers and therefore there will be competition in finding food and then to fight off the other birds so that you can get the food first.
