Answer:
The ventricles of the heart have thicker muscular walls than the atria. This is because blood is pumped out of the heart at greater pressure from these chambers compared to the atria. ... This is due to the higher forces needed to pump blood through the systemic circuit (around the body) compared to the pulmonary circuit.
Explanation:
The Human Heart — PT Direct
The molecules doesn't need energy to cross through.
The diffusion doesn't need protien, the molecules pass between phospholipids by passes protien. It moves smaller molecules. Facilitated need protien also hormone, and larger molecules.
I wish it makes sense.
I think you forgot to give the options along with this question. I have researched with the question and have found the options as well. Hope it helps you in your study. Among the choices that i have come up with, the option that says that temperate deciduous forests are less open than tropical rain forests.