Nucleus could be considered the place where the rollercoasters are controlled and stopped and started
        
             
        
        
        
Answer:
experiment
Explanation:
When you are controlling the conditions it is called an experiment.
 
        
             
        
        
        
Answer:
More individuals are produced each generation that can survive. Phenotypic variation exists among individuals and the variation is heritable. Those individuals with heritable traits better suited to the environment will survive.
 
        
             
        
        
        
Milliliter and liter for a liquid.
For a solid object, I would say meter and cubic centimeter