Answer: The answer is B- Diffusion of calcium ions through NMDA receptors. 
Explanation:
 Phantom limb pain (PLP) is a painful sensation experienced after the loss or amputation of a limb. The limb is no longer there but the individual can still feel real and severe pains in the limb. This occurs soon after surgery.
 NMDA is a receptor for Glutamate which is an excitatory neurotransmitter. The activation of NMDA receptors are associated with hyperalgesia which is an abnormally heightened sensitivity to pain. 
 
        
             
        
        
        
They put a camera up to the microscope! I’ve done that with my phone camera and it’s so cool!
        
             
        
        
        
Answer:
 air pollution can irritate your airways and may cause shortness of breath, coughing, wheezing, asthma episodes and chest pain. 
Explanation:
Hope this helps:)
 
        
             
        
        
        
Answer: B- Over time, beneficial variations will be passed on to future generations
Explanation: