Answer:
The Z lines and H- zone shortens during the muscle contraction.
Explanation:
Sarcomere is the area between the two Z lines. The Z- lines are present in the centre of I - band and H - zone is present in the A - band. The actin filaments which are thin filaments present in I- band and contracts, slide over the myosin filament during contraction. 
The I - band, H- zones are became shortens as they are thin than the A- band. It is anisotropic band having thick myosin filaments. They are not flexible and remain in its constant shape during the muscle contraction.
After the muscle contraction, the A- band and the H- zone comes to their original shape. In other words, the sarcomere shortens and comes back during muscle contraction, and relaxation.
 
        
             
        
        
        
Answer by YourHope:
Hi! :)
Explain the cellular functions that occur when antibiotics attack a bacteria cell.
When antibiotics attack a bacteria cell, the growth of the bacteria is stopped and the bacteria will not be able to divide and spread all over the body through the blood!
:)
 
        
             
        
        
        
Answer:
Work can be defined as transfer of energy. In physics we say that work is done on an object when you transfer energy to that object. If one object transfers (gives) energy to a second object, then the first object does work on the second object.
Explanation:
 
        
             
        
        
        
Photosynthesis takes place in the chloraplast