2. Why would the first life form probably have been a prokaryote rather than a eukaryote?

The oldest fossils, between 3.5 and 3.8 billion years old, are then accepted as both the first life and prokaryotic.

p

explanation:

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.