HEL PLSSS Which of the following describes the proper order of structures that an oxygen molecule diffuses through after entering the lungs?

Surfactant layer; alveolar space; capillary wall
Alveolar space; capillary wall; surfactant layer
Surfactant layer; capillary wall; alveolar space
Alveolar space; surfactant layer; capillary wall

What are the types of mutations, and how does each alter the encoded protein? college level answer

What effect does plate tectonics have an organic evolution

Which is an advantage of having memory cells when a pathogen is encountered for a second time. a) the memory cells are what proliferate into clones of cells in response to the binding of an antigen. b) memory cells are vital to the primary immune response in that they immediately recognize pathogens even at the first encounter. c) memory cells are essentially effector cells that are short lived and attack antigens even without having a receptor specific to that antigen. d) it ensures that more lymphocytes with a receptor specific to a particular antigen will be present than in a host that had never encountered that pathogen.