Answer: B
Explanation:
The T helper cell needs to acttivate the T cyctotoxic cell in order for the Tc cell to go do its work.
Once the TC cell is active it interacts with MHC-1 proteins on the surface of the infected host cell, this allows the Tc cell to recignise the host cell and begin secreting cytotoxins (perforins and granzymes) in order to degrade the infected cell and cause apoptosis (controlled cell death)
 
        
             
        
        
        
Answer:
ll.  Chlorine
Explanation:
Inbiochemical systems are oxygen (3.44) and nitrogen (3.04) while carbon (2.55) and hydrogen (2.22) 
 
        
             
        
        
        
Answer:
<h2>Cross out unnecessary phrases: Cut out introns.</h2>
Explanation:
The mRNA is a transcript of DNA . Primary mRNA transcript is edited before translation.
Mature mRNA is transcribed into protein, which is the final product of central dogma.
mRNA contains introns and exons , introns are removed by splicing.
the analogy of mRNA editing is Cross out unnecessary phrases: Cut out introns.