Answer:
Explanation:
I think it is: acetylcholine (neurotransmitter) - motor neuron - contract
second question: diffusion because of opening of ca2+ channels
Amphibians have three heart chamber and they lay eggs so
AMPHIBIAN
<span>The virus uses the cell to replicate itself and then moves on. The cell, after replication dies as the new virus spreads.
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It is an advantage due to the fact you do not have to think about it. therefore while sleeping you still breathe and you do not have to be conscious