A fat free diet is dangerous because IT CAN RESULT IN DEFICIENCY OF ESSENTIAL FATTY ACIDS. 
Essential fatty acids refers to those fatty acids that humans must eat in their foods because the body can not synthesize them and they are required for good health. There are three type of essential fatty acids, these are arachidonic, linoleic and linolenic acids. When these essential fatty acid are absent in one's diet they lead to ill health. 
        
                    
             
        
        
        
Answer:
-  Interruption in the genetic flow between separated groups
- The emergence of new mutations in each of the groups, and their accumulation in time. Slow and gradual differentiation between populations. 
- Genetic divergence by natural selection and reproductive isolation 
- Prezigotic isolation mechanisms 
Explanation:
Allopatric speciation consists of the geographic separation of a continuous genetic background that can give place to two or more new geographically isolated populations. These separations might be due to migration, extinction of geographically intermediate populations, or geological events. In this speciation, some barriers impede genetic interchange, or genetic flux, as the two new groups that are separated can not get together and mate anymore. These barriers might be geographical or ecological. 
The process of allopatric speciation involves different steps that affect organisms:
- The emergence of the barrier. 
- Interruption in the genetic interchange
- The occurrence of new mutations and their accumulation in time in each population. Slow and gradual differentiation. 
- Genetic divergence by natural selection and reproductive isolation makes it impossible for the two groups to mate even if the barrier disappears. 
- Prezigotic isolation mechanisms will be favored by selection if occurs a secondary contact between the new species in formation. 
 
        
             
        
        
        
False is the answer....i remember learning this