In recent molecular genetic studies, genes associated with the neurotransmitter Dopamine have been linked to ADHD. 
ADHD stands for Attention Deficit Hyperactivity Disorder. People with ADHD have a hard time focusing on tasks. Scientists have found that the low levels of dopamine in the brain are associated with the symptoms of ADHD. It is because the neurons in the brain have a high amount of protein called the dopamine transporters. These proteins block the dopamine from passing between the neurons. This decreases the effect of dopamine.
 
        
             
        
        
        
The older the Earth's crust, the denser it is.
        
             
        
        
        
In biology, cellular communication is a term used to determine distinct kinds of methods of communication among the living cellulites. Of these intercellular communication signifies the communication between the cells. In this kind of communication, membrane vesicle trafficking plays an essential role in both humans and animals.  
On the other hand, intracellular communication signifies towards the communication of the organelles in order to sustain cellular homeostasis.  
 
        
             
        
        
        
Answer:
The water treatment plant does not work properly.
Explanation:
The data from the river samples showed that there was a problem with the water treatment plant because there is high amount of pollutants are present in the river sample. The presence of pollutants in the samples shows that the water treatment plant did not work properly, if they did no pollutants are present in the river water so this presence of pollutants indicates inefficiency of water treatment plant.
 
        
             
        
        
        
Answer:
Heat energy is required to establish the electron transport chain
Explanation:
The rest of the choices are true about mitochondrial chemiosmosis