Substitution mutation is when a single base pair in a strand of DNA is replaced. This can cause an early stop amino acid, or the protein could change slightly, or the protein could be unchanged completely due to there being multiple base pairs to make an amino acid.
 
        
             
        
        
        
Answer:
nervous system
Explanation:
the cns oversees every action our body does
 
        
             
        
        
        
Answer:
The correct answer is case control study. 
Explanation:
A study in which a comparison is made between the patients carrying the disease with the patients not carrying the disease is known as the case-control study. In the mentioned study, the one carrying the disease is termed as cases, and the one that does not possess the disease is termed as controls.  
This form of study is generally done to predict the association between the disease and the risk factor. In case-control studies, only observation is done as no attempt is made to change the course of the condition. The prime objective of the study is to predict the exposure of the risk elements for the individuals present in two groups, that is, controls and cases. This form of study is also called case-referent studies or retrospective studies.  
 
        
             
        
        
        
Answer:
esophagus, pancreas, liver, gallblader, salivary glands
Explanation: