Answer:
A polar molecule is a molecule that has a positive and negative charge at either end.
The main responsible for the delay among the atrial and
ventricular contractions is the action potential conduction velocity of the AV
node cells. If the atria and ventricles contract simultaneously, atria cannot
give any help in filling the ventricles, which is needed, especially in those
with stiff ventricles as in the elderly. Hence atria have to contract first and
then the ventricles.
"Water depth" is the factor among the choices given that has the <span>greatest importance in determining the characteristics of an aquatic ecosystem. The correct option among all the options given is the second option.
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<span>Many sexually active american adolescents fail to avoid pregnancy because they are not educated on contraceptive methods. </span>
