Answer:
up-regulation
Explanation:
Upregulation is where a increases the quantity of a cellular component like protein or RNA in response to an external stimulus.By controlling the number of its receptors, cells may increase and decrease their cell sensitivity.... Hormones can also trigger cells to control themselves by upregulation.( Estrogen is the primary sex hormone for females).
 
        
             
        
        
        
The immune response is the body's defense mechanism against the pathogens. The immune response of the body protects it from bacteria, viruses and multiple other disease causing organisms. The normal development of this protective immune response of the body is produced by as a result of the hormones which are produced by the thymus gland. The thymus gland produces the T-lymphocytes, which are important for a healthy immune response. The thymus gland secretes thymosin which is crucial for the development of these cells.
Hence, the answer is 'thymus gland'.
 
        
             
        
        
        
The seeds are enclosed because it's the plants way of protecting them.
        
             
        
        
        
At the base of the food chain
        
                    
             
        
        
        
The Trout are probably not used to the water and their surroundings.