What will happen to the heart beat if sodium is blocked from crossing the cell membrane?

The heart will never have a ventricular cell action potential because the increased sodium permeability is important in activating the voltage gated fast acting sodium channels. Without depolarization, there will be no heart beat.

What are three pieces of evidence of the hypothesis that mitochondria originated as bacterium?

Mitochondria has its own DNA, the DNA is circular, and it divides by fission. It is also important to remember that mitochondria is passed maternally.

If the posterior division of the Internal Iliac artery was blocked, which organs would see a reduction in blood flow?

The organs and regions affected would be the gluteal region, the posterior abdominal wall, the spinal meninges, and the deep back muscles dorsal to the sacrum. The posterior division of the internal iliac artery gives rise to the iliolumbar artery, lateral sacral artery, and the superior gluteal artery which supplies the regions mentioned above.