Neils Bohr proposed that electrons are found in different energy levels around the nucleus
 
        
                    
             
        
        
        
Answer:
The sympathetic nervous system originates in the spinal cord and its main function is to activate the physiological changes that occur during the fight-or-flight response. This component of the autonomic nervous system utilises and activates the release of norepinephrine in the reaction.
 
        
             
        
        
        
Answer:
Heritable variations exist in each population.
Each species seems suited for its particular environment.
A population has more individuals than can be supported by the environment.
Explanation: