Active Transport

Question 1

Second stage

Answer 1

2) Sodium ions therefore diffuse into the epithelial cells by facilitated diffusion.
As it is co-transport the protein carrier also carries across a glucose molecule

Question 2

Third stage

Answer 2

Glucose molecule diffuses into the blood stream by facilitated diffusion

Question 3

Why is the movement of glucose indirect active transport?

Answer 3

The concentration is sodium ions controls the movement of glucose; and as sodium was initially actively transported, energy was therefore required to move glucose across.

Question 4

First step of co transport in the ileum

Answer 4

1) Sodium ions are actively transported by the NaK pump into the blood.
This creates a high concentration gradient from the lumen to the epithelial cell.