Answer:
Hair cells are present inside the inner ear that acts as a receptor of sound. Researchers affirmed that once there is a damage to the hair cell, it can regenerate in birds. 
Damage hair cell can lead to loud noise which in turn affect the ear. The supporting cells are present along with the hair cells. When the hair cells get damaged, the supporting hair cell gets the signal to start the process of regeneration. 
 
        
             
        
        
        
Answer: a) Bacteria
Example of a disease caused by bacteria – 
Tuberculosis (TB) is a kind of respiratory disease caused by bacterium called Mycobacterium tuberculosis.
B) Fungi
Example of a disease caused by Fungi
Athlete's foot is a fungal disease caused by Trichophyton (hopefully this helped)
        
                    
             
        
        
        
Answer:
more flexibility in movement
Explanation:
it allows the worm to pass waves of movement along its body to move through loose earth.