Maybe immune system and respiratory system
        
             
        
        
        
Answer:
The Rf values indicate how soluble the particular pigment is in the solvent by how high the pigment moves on the paper. 
Explanation:
The Rf values indicate how soluble the particular pigment is in the solvent by how high the pigment moves on the paper. Small Rf values tend to indicate larger, less soluble pigments while the highly soluble pigments have an Rf value near to one.
 
        
             
        
        
        
Answer:
disturbance has destroyed population in a community
Explanation:
The secondary succession occurs after there has been some disturbance that has manged to badly damage or destroy the populations in a community. This basically means that after some catastrophic event that happened to a certain population or populations, other species moved in to colonize the freed space. There are countless examples of secondary succession in nature, and one of the best is when there is a strong volcanic eruption. The volcano manages to destroy the population of plants and animals in its close surroundings, but after the eruption ends, the space starts to be colonized by new plants and animals step by step until they create a new well functioning community.
 
        
                    
             
        
        
        
The most important reason they are considered non living is because they cannot live and reproduce without the help of a host cell.