Digestion & Absorbtion

Question 1

Cells lining the ileum of mammals absorb the monosaccharide glucose by co-transport with
sodium ions. Explain how

Answer 1

1. Sodium ions actively transported from ileum cell to blood;
2. Maintains diffusion gradient for sodium to enter cells from gut with glucose
3. Glucose enters by facilitated diffusion with sodium ions;
4. Glucose enters blood by facilitated diffusion

Question 2

Galactose has a similar structure to part of the lactose molecule.
Explain how galactose inhibits lactase.

Answer 2

1. Galactose is a competitive inhibitor / attaches to the active site (of lactase);
2. Fewer enzyme substrate complexes formed between lactase and lactose