Answer:
 The left side of the heart receives oxygenated blood from the pulmonary vein and pumps it into the aorta, while the right side of the heart receives deoxygenated blood from the vena cava and pumps it into the pulmonary vein. The pulmonary vein and aorta also have valves connecting them to their respective ventricle.
Explanation:
 
        
             
        
        
        
I believe blood vessels constrict
        
                    
             
        
        
        
Answer:
The correct answer is option A, the type of isotope
Explanation:
The half life of a radioactive substance is a constant value and thus it is not affected by the temperature, catalyst or mass of the substance.  Basically it is the time taken by a radioactive substance to reduce its mass by half of its actual value. Radioactive decay takes place only when the atomic nucleus becomes unstable and thus the isotope type is the only factor which affects the radioactive decay of any element.  
 
        
             
        
        
        
Answer:
Look at the explanation!
Explanation:
The Mercator map projection is a cylindrical map projection that was presented by Gerardus Mercator in 1569. Gerardus  Mercator was a Flemish geographer and cartographer. It became the standard map projection for navigation because of it's cool one of a kind property of "representing any course of constant bearing as a straight segment."
 
        
             
        
        
        
Answer:
B. introns; exons
Explanation:
Related genes from different organism usually translate to proteins of indispensable functions. This means that the proteins must be similar in terms of amino acids produced. Therefore the coding region must be highly conserved. These can be found in the introns. Conversely, exons are not a part of the coding sequence and therefore not required for translation. These sequences may be less conserved.