Answer:
Researchers also found that the longer a male's tail feathers, the faster he was able to shake them. This effort would require more muscular strength, and might be a powerful signal of fitness to the females.
Explanation:
 
        
             
        
        
        
Answer:
stronger and longer organ are able to mate more with females, whereas the shorter one didn't stand a chance.
 
        
                    
             
        
        
        
Answer:
1. Nerve impulse
2. Neurons
Explanation:
Neurotransmitters are compounds with low molecular weight. They are secreted by axon terminals of the neurons. The released neurotransmitters then bind to the receptors located on next neuron or on the surface of muscle cell.
The function of neurotransmitters is to carry the nerve impulse from presynaptic neuron to the postsynaptic neuron or from neurons to the effector organs such as muscles and glands.  
For example, neurotransmitters are released into the synaptic cleft to transmit the nerve impulse between neurons.  
 
        
             
        
        
        
Smooth er has less things inside of it and rough is more complex.