I just have a question, are you in seventh grade? I keep my binders from past years and I remember learning this, but don’t know if that’s the grade I learned it in, are you?
Alveolar walls are thin to enable the quick passage of oxygen in and out of the lungs. The lungs works hand-in-hand with the heart and also is responsible in converting blood that's de-oxygenated into an oxygenated blood that is usable by the organ systems of the body. The alveolar walls are also designed to have thin membranes so that it can expand and constrict quickly allowing us to breather properly.
Answer: C
Explanation: The Moon has phases because it orbits Earth, which causes the portion we see illuminated to change. The Moon takes 27.3 days to orbit Earth, but the lunar phase cycle (from new Moon to new Moon) is 29.5 days.
Dogs are omnivores, eating a mix of protein and grain and much more
