Jobs.... they do different jobs.
Answer: The SA node
Answer choices are:
<span>A. </span>The AV node
<span>B. </span>The SA node
<span>C. </span>The purkinje fibers
<span>D. </span>The AV bundle
The SA node<span> is the heart's natural pacemaker consisting of a cluster of cells located in the upper part of the wall of the right atrium. (the right upper chamber of the heart). The electrical impulses are produced and sent out from there to regulate heartbeat. This is also called the sinus code. </span>
That's true. There is little variety among organisms found in pools, pounds and lakes. Despite that fact that many ponds are seasonal, lasting just a couple of month (for exemple sessile pools) while lakes can exist for more than hundred years. Lakes and ponds have limited species diversity because they are often limited from each other and from other water sources like rivers, seas and oceans.
A. Migration (birds migraye to warmer climates during colder months)
