Among the non-mammalian vertebrates, the cloaca is an anatomical structure that function as a shared pathway for the digestive, excretory, and reproductive systems. Cloaca in vertebrates, common chamber and outlet into which the intestinal, urinary, and genital tracts open. It is present in amphibians, reptiles, birds, elasmobranch fishes, and monotremes.  Cloaca is not present in placental mammals or in most bony fish.
        
             
        
        
        
The best answer is A.
The shape of a protein is determined by its primary structure. The primary structure is the sequence of amino acids  in each polypeptide chain which make up a protein.
The sequence of amino acids is basically a list of amino acids that are linked to each other to form a chain which is known as a polypeptide chain.
The structure of the finished protein will depend largely on the first  (primary) chain of amino acids to be produced to make up that protein. 
 
 
        
             
        
        
        
The 10% rule means that when energy is passed in an ecosystem from in trophies level to the next , only 10 percent of the energy will be passed on. but ten percent of the energy in organic matter is stored as flesh , the remains is lost during transfer. or broken down in reespirations.
        
             
        
        
        
Two things that can occur is water levels may rise and the earth can get warmer.