It carries signals for the body through nerves (answer 3)
        
             
        
        
        
Answer:
Darwin's theory consisted of two main points; 1) diverse groups of animals evolve from one or a few common ancestors; 2) the mechanism by which this evolution takes place is natural selection. This SparkNote will first take a look at Origin of the Species, and then more closely examine Darwin's theories.
 
        
                    
             
        
        
        
In plant seeds, the photoreceptor phytochrome is responsible for the process termed photomorphogenesis<span>. This occurs when a seed initially situated in an environment of complete darkness is exposed to light. A brief exposure to electromagnetic radiation, particularly that whose wavelength is within the red and far-red lights, results in the activation of the photorecepter phytochrome within the seed. This in turn sends a signal through the signal transduction pathway into the nucleus, and triggers hundreds of genes responsible for growth and development</span>
        
             
        
        
        
It entera from your body to the middle and then to the back and again.