The action of the carrier protein X in Figure 1 is linked to a membrane-bound ATP hydrolase enzyme.

Explain the function of this ATP hydrolase.

The movement of Na+ out of the cell allows the absorption of glucose into the cell lining the ileum.

Explain how.

Describe and explain two features you would expect to find in a cell specialised for absorption.

1

2

Figure 2 is a diagram of one SGLT1 carrier protein.

Draw phospholipids on Figure 2 to show how the carrier protein, SGLT1, would fit into the cell-surface membrane.

Do not draw more than eight phospholipids.

Figure 2 shows the SGLT1 polypeptide with NH2 at one end and COOH at the other end.

Describe how amino acids join to form a polypeptide so there is always NH2 at one end and COOH at the other end.

You may use a diagram in your answer.

Space for diagram: