A is the answer hope i helped
Answer:Tissue
Explanation:Heart muscle cells beat in unison to push blood in timing with the rhythm of the heart, at the direction of nearby nerve cells. These muscle cells could best be called. Tissue. As cell division proceeds, the cells increase in number, but also become specialized in structure and function.
The second option: meiosis and fertilization
process A is meiosis, you can see that the gamete(haploid cell) results from the diploid cell. The gamete has n chromosomes(39), whereas the diploid cell has 2n(78)
process B is fertilization the two gametes(haploid) fuse together to form the zygote(diploid)
The right answer is <span>Refractory period.
At the moment when the action potential is emitted, the fiber being depolarized, it is impossible to depolarize it again. It is, therefore, necessary to wait until the membrane potential returns to a value below the critical threshold in order to be able to excite it again. We are thus led to distinguish two periods that characterize its excitability.
An absolute refractory period: during which any stimulation, even supraliminal, is ineffective since the fiber is already depolarized.
A relative refractory period: during which a second action potential can be omitted provided that the depolarization produced by the excitation reaches the critical threshold, which implies that it is more important since the value of the resting potential has not been restored yet.</span>
Answer:
(B) They Bind to receptor proteins on the surface of the postsynaptic neuron.
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