(a)

Fig. 1.1 is a diagram representing part of the phospholipid bilayer of a cell surface membrane.

Fig. 1.1

[ 1 ]

(i)

Cholesterol is an important lipid component of many cell surface membranes. Fig. 1.2 shows the structure of a cholesterol molecule.

Fig. 1.2

Using the information in Fig. 1.2, explain the orientation (positioning) of cholesterol molecules in the phospholipid bilayer, as shown in Fig. 1.1.

[ 1 ]

[Maximum number: 1]

Where in the cell surface membrane are the carbohydrate chains of glycoproteins and glycolipids mainly located?

glycoproteins

glycolipids

inner surface

outer surface

inner surface

outer surface

[Maximum number: 1]

Fig. 6.1 is a diagram of the cell surface membrane of a squamous epithelial cell lining an alveolus.

Fig. 6.1

(a)

(i)

With reference to Fig. 6.1, state how to identify the external surface of the cell surface membrane.

[ 1 ]