The allantois is one of the components of amniotic egg that handle waste collection and management in the embryo. It stores metabolic waste products, mainly uric acid. As the embryo grows in size, allantois also handle gas exchange.
D. They had to see if this new idea fit the evidence they found in their experiments.
Answer:
There are four chambers of the heart:
The two bottom chambers are the right ventricle and the left ventricle.
The two top chambers are the right atrium and the left atrium.