Answer:
constant = changes and control is used as the basis of comparison 
Explanation:
Constant variables are variables that do not change 
e.g such as the temperature ( if it's meant to be kept at a constant temp). 
Control variables are meant to be kept constant to allow for a comparison and thus determine the effect of IV (independant variable) and DV ( dependant variable) 
 
        
             
        
        
        
I think the correct answer from the choices listed above is the third option. The term that describes all of  the non-living components of an ecosystem would be abiotic. Abiotic<span> components or </span>abiotic<span> factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems.</span>
        
                    
             
        
        
        
Mitosis is a type of cell division which results in two daughter cells which have the same number and kind of cells as the parent nucleus.  Mitosis is used to replace worn out cells and for growth.  In plants, a new cell was is built between the daughter cells, while in animals the cell membranes constrict and pinch the parent cell into daughter cells. 
        
             
        
        
        
There are two basic ways to measure exercise intensity:
How you feel. Exercise intensity is a subjective measure of how hard physical activity feels to you while you're doing it — your perceived exertion. ...
Your heart rate. Your heart rate offers a more objective look at exercise intensity.