chapter 3 : plasma membrane

(a)  The plasma membrane is said to be semi-permeable.

       What is the meaning of ‘semi-permeable’?

        A semi-permeable plasma membrane allows only certain substances
         to move freely across it while others cannot. 

(b) Describe how the particle moves across each of the following structures. i-Carbon dioxide / Oxygen / Glycerol /Fatty acid by Simple diffusion  through phospholipid bilayer ii-Water  by osmosis through pore protein iii -Glucose /Amino acid by facilitated diffussion through carrier protein iv- Sodium ion/pottasium by active transport through carrier protein and needs energy of ATP. /Potassium ion