every cell has work to do but different cells may have different jobs in multicellular organisms, cell with the same type of job often work together. These group of specialized cell from tissue in turn, tissue often group together to form larger units called organs the heart is an organ; so is the stomach.
 
        
             
        
        
        
The messenger RNA is a single-stranded intermediate
molecule that transfers the genetic information from DNA to the cytoplasm,
which is used as a template to assemble the chain of amino acids that form a variety of polypeptides. Therefore, mRNA is the blueprint for
protein synthesis, which is read according to the genetic code during gene
expression.
 
 
        
                    
             
        
        
        
I think it’s T lymphocytes? 
It says: T lymphocytes attack antigens directly and help control the immune response. They also release chemicals, which control the entire immune system....
        
                    
             
        
        
        
Explanation:
Space exploration thus supports innovation and economic prosperity by stimulating advances in science and technology, as well as motivating the global scientific and technological workforce, thus enlarging the sphere of human economic activity.
 
        
             
        
        
        
The alveoli. These little air sacs are found on the end of the bronchioles and are the place where oxygen enters the blood and the carbon dioxide leaves.