Crystals, good insulators, hard and brittle,conduct electricity, high melting and boiling points
        
                    
             
        
        
        
Answer AND Explanation:
There is a large number of biochemical reactions taking place in a cell at any given time. Enzymes being biological catalysts control these reactions and regulate them so that they proceed at a pace that is suitable for sustaining life. Thus enzymes regulate cellular activities. Enzymes also ensure that only the required reactions take place and progress to their appropriate extent.
 
        
             
        
        
        
The right answer is The cells are damaged.
Take the example of skin cells.  
The skin consists of two tissues:
* the outermost, the epidermis, resting on a vascularized connective tissue,
* the dermis.
In the epidermis, which includes several layers of cells, the outer layer is formed of dead cells that are desquamating and are constantly being replaced from proliferating basal cell cells. So, in normal conditions, the epidermis is in constant renewal.
On the other hand, when accidentally, the upper parts of the epidermis are damaged, for example, a slight abrasion or of a burn, the destroyed portion is regenerated (replaced) thanks to an accelerated proliferation of basal epidermal cells .