Answer:
Explanation:
I think it is: acetylcholine (neurotransmitter) - motor neuron - contract
second question: diffusion because of opening of ca2+ channels
Answer:
Number of bacteria required 
Explanation:
Given -
Size of each bacterium 
micrometers long
These bacteria are arranged end to end.
The size of chain to be formed is equal to 
centimetres
Let us say that in forming a chain of centimetres nearly X number of individual bacterium are required.
hence, number of bacterium required to form centimetres chain can be represented as
Number of bacteria required
Nerve cells are functionally classified as sensory neurons, motor neurons, or interneurons. Sensory neurons (afferent neurons) are unipolar, bipolar, or multipolar shaped cells that conduct action potentials toward or into the central nervous system.
