Answer:
A
The amoeba has a very simple digestion mechanism.
It obtains food by phagocytosis, breaks them down by the use of enzymes and absorbs the food into its cytoplasm by diffusion.
The rat chews up the food with teeth in its mouth, mixes it with saliva (which contains ptyalin - an enzyme) which helps to further break down food and then swallows to transport the masticated food into the stomach through its oesophagus.
In the stomach, the food is further broken down by gastric juices and bacteria that comes with the food is killed before the food is absorbed in the small intestine and cellulose is digested in the Caecum.
The food passes from the small intestine to the large intestine, where the water it contains is absorbed and the waste expelled via the anus.
B
In the Amoeba, the organelles are the most specialized structures. The organelles carry out a lot of cellular functions like the production of fuel and transportation of protein molecules.
In the rat, all its organs are specialized to carry out various functions. The digestive system is specialized, the central nervous systems are specialized, the skeletal system is specialized to its mechanical functions, the circulatory system is specialized etc.
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