The correct answer is option A. They either match up with a receptor molecule on the surface of the cell or enter the cell through the membrane.
The intercellular signals are the signals, which transfer the signals from one cell to the another and the intracellular signals are those signals, which carries message within the cell. 
The intercellular signals may or may not be transferred through the gap junctions. The chemical signals are one of the type of the cell signals. The chemical signalling molecules generally have a receptor on the cells, where these molecules can bind and can be cause the activation of the cell. The chemical signals can also enter into the cells through active transport and facilitated diffusion. So, these type of transports does not go through the Gap junction.
 
        
                    
             
        
        
        
Parasites need a host. If a host tries to get rid of the parasite or kill it, then the parasite either has to leave the body or die.
        
             
        
        
        
Answer:
Deoxyribose, found in DNA, is a modified sugar, lacking one oxygen atom (hence the name "deoxy"). This difference of one oxygen atom is important for the enzymes that recognize DNA and RNA, because it allows these two molecules to be easily distinguished inside organisms.
Explanation:
 
        
             
        
        
        
Answer:
Plant biomass will increase as a result of photosynthesis. During photosynthesis, plants produce glucose and oxygen from carbon dioxide and water, using light energy from the Sun. ... Photosynthesis is an endothermic reaction as it requires light energy to react carbon dioxide and water to produce glucose and oxygen.
 
        
             
        
        
        
No. Deep Brain Stimulation blocks the defective electrical signals that can cause tremors and more movement symptoms.