Messenger RNA (mRNA) molecules carry the coding sequences for protein synthesis and are called transcripts; ribosomal RNA (rRNA) molecules form the core of a cell's ribosomes (the structures in which protein synthesis takes place); and transfer RNA<span> (tRNA) molecules carry amino acids to the ribosomes during protein synthesis.</span>
        
             
        
        
        
The movement of substances (as by diffusion) across a cell membrane without the expenditure of energy.
 
        
             
        
        
        
The answer should be advantame
 
        
             
        
        
        
Answer:
Thymus gland
Explanation:
it is active during puberty mostly and after slowly shrinks