The ion which is entering axon terminal A is called Ca²⁺.
The effect which it has is, it causes the release of neurotransmitter from the axon terminal.
Axon terminal is termed as distal termination of telodendria of an axon. Another name for the axon terminal is synaptic boutons. Axon is a long, slender projection which is of a nerve cell. 
Their work is to conduct electrical impulses which are referred to as action potential which is a way of neurons of the cell body. Neurons use electrochemical signals and also a neurotransmitter chemical which transmits impulses from one neuron to another.
Axon terminals are being separated from neighboring neurons by a gap known as a synapse. Both the axon terminal and neuron they come from a point which is called the presynaptic neuron.
        
                    
             
        
        
        
The answer is c hope that helped
        
                    
             
        
        
        
Answer:
All living organisms share several key characteristics or functions: order, sensitivity or response to the environment, reproduction, growth and development, regulation, homeostasis, and energy processing.
 
        
             
        
        
        
The  cross  of  heterozygous  
AaBb as  parental  phenotype led   to  formation  of  1
6  phenotype   of  the  offspring.This  is  because  this  is  dihybrid   form  of inheritance .The   probability  of  having  
aabb   offspring  is  
1/16  since   there  is  only  one  aabb  type  of  offspring  phenotype  out  of 
 the
  16.  An  illustration  of  how  crossing  is  done  is  as  per  punnet square  below
 
        
        
        
Mono hybrid cross dihybrid cross homozygous cross heterozygous