Answer: See below
Explanation:
There should be another answer that can be chosen: the rat’s chemical receptors detect chemicals in the fruit that alert the rat to possible danger. Sensory receptors in the rat's whiskers respond to input about the texture of the fruit, maybe it's slimy or rancid, if if it was another factor such as the environment, it wouldn't have approached the fruit in the first place.
 
        
                    
             
        
        
        
Answer: to study genetics
        
             
        
        
        
<span>It is called a substrate. </span>
        
                    
             
        
        
        
Answer:
Through negative feedback, insulin produced by the pancreas causes a decrease in the amount of glucose in the blood. 
Explanation:
The control of blood sugar (glucose) by insulin is a good example of a negative feedback mechanism. When blood sugar rises, receptors in the body sense a change. In turn, the control center (pancreas) secretes insulin into the blood effectively lowering blood sugar levels.