Question 4
Which of the following would be considered a form of active transport?
o the movement of oxygen molecules from high concentration in the blood to low concentration in the cell.
O the movement of carbon dioxide from high concentrations in the cell to low concentrations in the blood.
o the movement of glucose into the cell down its concentration gradient,
o the movement of sodium atoms from low concentration in the cell to higher concentrations outside the cell.
The most important property of the cell membrane<span> is its selective permeability: </span>some substances<span> can </span>pass through<span> it freely, but others cannot. Small and nonpolar (hydrophobic) molecules can freely </span>pass through<span> the </span>membrane<span>, but charged ions and large molecules such as proteins and sugars are barred passage. </span>
Mechanical digestion takes place in the mouth
