You are presented with a heart from an unknown organism. Upon studying the heart, you note that it has a small node of tissue in the right atrium and that it has a single aorta leading directly from the left ventricle. Based on these observations, from what kind of organism must this heart have come from?
A) Reptile
B) Amphibian
C) Bony fish
D) Bird or mammal
E) Cartilaginous fish

Question

Quizplus · Accepted Answer

The presence of a single aorta leading directly from the left ventricle is characteristic of birds and mammals, which have a four-chambered heart allowing for complete separation of oxygenated and deoxygenated blood. The small node of tissue in the right atrium is likely the sinoatrial (SA) node, which is present in the hearts of birds and mammals and acts as a natural pacemaker.

You Are Presented with a Heart from an Unknown Organism