The atrial cells and ventricular cells are connected to each other using gap junction so that the wave of depolarization can directly spread from the atrium to the ventricle without the AV node. a.true b. false.

The given statement is true.

Explanation:

The atrial cells and ventricular cells are connected to each other using gap junction so that the wave of depolarization can directly spread from the atrium to the ventricle.  This is true.But, not without using the AV nodes. Through myocytes, the depolarizing waves pass much slower than the atrioventricular cells. AV nodal cells conduct them much faster than the atrial and ventricular cells. This system works as a standby. If there is some problem with the AV node, the atrial and ventricular cells will be able to spread the depolarizing waves with the help of gap junctions and without bothering the AV node.

This is a time line from 685 to 978

No because the eaeht is on a 23.5 degree axis tilt and so when it is winter the northern hemisphere is pointing away from the sun and the soutubern hemisphere is pointing toward the sun