The beginnings of a brain first become apparent around four weeks after conception when the neural plate folds to form the neural tube
<span>Organs are formed by tissues combined together.
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<span>Without variation, there is no difference between members of a population to be "selected for" in the first place. This is a basic tenet of natural selection. A new trait must arise in order to advance or decrease the fitness of the individual, and hence, its ability to pass on its genes.</span>
Answer:
Hydrogen, Lithium, Aluminum, Argon, Nickel, Iodine, Gold, Mercury
Explanation:
Hydrogen has 1 proton.
Lithium has 3 protons.
Aluminum has 13 protons.
Argon has 18 protons.
Nickel has 28 protons.
Iodine has 53 protons.
Gold has 79 protons.
Mercury has 80 protons.
Hope this helps.
<span>Pacinian corpuscles are rapidly adapting mechanoreceptors so they respond only at the onset and offset of the stimulus. The Pacinian corpuscle has a single afferent nerve fiber. Its end is covered by a sensitive receptor membrane whose sodium channels will open when the membrane is deformed in any way. Pressure thus causes sodium to enter the neuron and create a generator potential. If this potential reaches a certain threshold nerve impulses are formed. This impulse is now transferred along the axon with the use of sodium channels and sodium/potassium pumps in the axon membrane. The magnitude of the stimulus is encoded in the frequency of impulses generated in the neuron. So the more massive or rapid the deformation of a single corpuscle, the higher the frequency of nerve impulses generated in its neuron.</span>
