s would be secondary Explanation:
just cause
Answer:
Polar molecules are unable to go across unless they are crossed with the help of the protein channel.
Due to the semi-permeable nature of the plasma membrane polar molecules and molecules with high molecular weight are unable to cross the membrane.
Their transportation across the cell membrane is facilitated by integral transmembrane proteins or carrier proteins which form channels across the membrane.
For example, fructose in the small intestine is transported into the cell with the help of GLUT5 transporter.
Adenine binds with Thymine