Some samples are transparent, or very difficult to see, therefore, they are stained in order to be seen more clearly and easier to work with.
During eye surgery, the clear layer of the eye is stained to be easily extracted, if it was clear then the surgeon might cut the eye instead of just the layer.
Hope this helps, u might want to search online for more info.
        
                    
             
        
        
        
Answer: Environmental responsibility. ... Respect the environment, making rational use of natural resources and taking steps to prevent pollution from the different processes involved in our industrial operations. Promote the sustainable use of raw materials and natural resources. In fact, our cognitive ability and understanding of nature obliges us to maintain the integrity of the environment. So we must change how we influence the land. We must respect the natural order of things and find a way to live accordingly. 
Accordingly u can take points from this and then add to ur ans. I hope i was helpful
 
        
                    
             
        
        
        
Gonads are the body structures that produce sex cells. Sperm are the male sex cells. Eggs are the female sex cells. Chromatin are threadlike DNA found inside the sex cells.
        
                    
             
        
        
        
A to move around is the answer
        
             
        
        
        
<span>Electrical signals in the body are often based on ions because ions are charged particles</span>