Answer:
Population is defined as a group of organisms, which belong to the same species. Example- Human population includes a group of organisms that all belong to the species sapiens
Explanation:
 
        
             
        
        
        
I think it is yes because they are both studies. Pharmakinetics is the study of an organism affecting a drug which could theoretically and potentially affect the result on how a drug affects an organism. I hope this helps you. I am not completely sure though. Just my logic speaking.
        
             
        
        
        
Answer:  stimulus (plural: stimuli). 
Explanation:
 
        
                    
             
        
        
        
Answer:
siRNA.
Explanation:
The RNA interference may be defined as the evolutionary conserved mechanism that helps in the gene regulation by the silencing of the small RNA molecules. Two main types are  siRNA and miRNA.
The siRNA (small interference RNA) is involved in the protection of the cell by destroying the exogenous ds DNA of the cell. The DICER  enzyme plays an important role in the processing of the small interference RNA and the guide strand of RNA is involved in the gene silencing.
Thus, the answer is option (a).
 
        
             
        
        
        
<h2>Epigenetic modification </h2>
Explanation: 
A methyl group bound to DNA inhibits transcription of a gene describes an epigenetic modification
Epigenetic modifications include: histone modifications and methylation
Methylation is the main cause of gene silencing for example methylation at lysine residue of histone protein, H4 leads to gene repression 
Small silencing RNA molecules are of two types: micro RNA (miRNA) and small interfering RNA (siRNA) 
miRNA directs degradation of target mRNA when makes perfect complementary while suppress mRNA translation when makes partial or imperfect complementary 
siRNA primarily mediates degradation of target RNA