Answer:
pulmonary vein
Explanation:
The pulmonary veins 
 transfer oxygenated blood from the lungs to the heart. 
It helps complete the pulmonary circuit, by receiving oxygenated blood in the alveoli and returning it to the left atrium.
 
        
             
        
        
        
Answer:
A. whether the glycoproteins or capsid proteins on its surface recognize those of the host cells.
Explanation:
Virus has different surface proteins that are recognized by the receptors present on its host cell. The range of a virus is determined by the recognition of these proteins by the host cell.
The interaction between the receptor on the host cell and surface proteins on the viral capsid is important for viral genome entry in the host cell and to determine the range of the host cells.
If the surface protein of the virus is not able to bind to the receptor on any cell then the virus can not infect the cell. For example, the HIV virus infects only those cell which have CD4 receptors. So the right answer is A.
 
        
             
        
        
        
ami tellement désolé tellement je ne connais pas cette langue mais salut mon ami
 
        
             
        
        
        
C
Hot springs are heated by the geothermal heat- heat from the Earths interior.
        
             
        
        
        
Answer:
The nitrogenous bases guanine and adenine are A. purines.
Explanation:
Adenine and guanine are purines, whereas the other two bases in DNA (thymine and cytosine) are pyrimidines.  The main difference between purines and pyrimidines is the number of rings that the base has: purines have two rings while pyrimidines only have one ring.  
In addition, phosphate group and sugar group cannot be the answer to this question because these two elements in addition to a nitrogenous base makes up a nucleotide.
Hope this helps!