A. the volcanic eruptions of Mt. Vesuvius
        
                    
             
        
        
        
The eggs of the fluke are passed into water supplies from feces and urine of infected people. After hatching the parasite actively swims and invades the body of a snail, usually by penetrating through the snail's foot. The parasite requires the presence of certain species of snails (e.g., Oncomelania, Biomphalaria, Bulinus) to transform (and multiply) itself into an infective stage, called cercaria.
 
        
        
        
Gene expression in prokaryotes can be regulated at multiple stages including transcriptional and co-translational. Operons respond routinely to the presence of specific metabolites and change the availability of activators and repressors while speific end products of biosynthetic pathways can regulate the translatability of mRNAs for new proteins.
        
             
        
        
        
Blood group o; a universal donor and blood group B
        
             
        
        
        
Answer:
Chemiosmosis is the movement of ions across a semipermeable membrane bound structure, down their electrochemical gradient. An example of this would be the formation of adenosine triphosphate by the movement of hydrogen ions across a membrane during cellular respiration or photosynthesis.