Besides supporting and protecting a cell, the cell membrane regulates what enters and leaves the cell.
I am soo sorry this is 4 hours late!!! Hope this helps!!! :)
The answer is the apoplast, the symplast, and the transmembrane pathway.
1. The apoplast pathway occurs through cell walls and space between cells. So, water does not cross any cell membrane as it travels this pathway.
2. The symplast pathway occurs through the continuum of cytoplasm. So, water travels through plasmodesmata which connect cells.
3. The transmembrane pathway occurs across cell membranes. So, water enters the cell on one side of the membrane and exits on the other.
Air passes through is: Nostrils → nasal cavity →Pharynx → Larynx →Trachea → Bronchi (with cartilaginous rings) →Bronchioles (without rings) → Alveoli (air sacs). Alveoli are the seat of exchange of O2 / CO2 between lungs and blood.
