<span>The answer is a certain required chemicals must be actively
transported.  Blood brain barrier is a
selective membrane that separates blood circulating from the brain and the
fluid of extracellular in the central nervous system. This is also called a
filtering mechanism, the capillaries that carry blood to the brain and spinal
cord tissue blocking the path way of the certain substance.</span>
 
        
             
        
        
        
Using the fossil record, you can categorize species based on analogous or homologous structures
        
             
        
        
        
I believe it’s circulatory system.
        
             
        
        
        
The ATP molecule act as a power source for a cell. it is someone's compared to a battery.
        
             
        
        
        
Answer:
D. They shrink to increase body temperature
if wrong sorry ya based on my syllabus