2 - Digestion

Question 1

Adaptations of Ilium

Answer 1

Villi

Thin walls

Presence of channel and carrier proteins for facilitated diffusion

Good blood supply to maintain a concentration gradient

Question 2

Parts of small intestine

Answer 2

Duodenum
Jejunum
Ileum

Question 3

Protein Digestion

Answer 3

Hydrolysed by enzymes called peptidases

Endopeptidase
-Break down peptide bonds between amino acids in the middle of a polypeptide chain

Exopeptidase
-Break down peptide bonds between amino acids at the end of a polypeptide chain

Membrane-bound dipeptidase
-Break down peptide bonds between last two amino acids left

Question 4

Lipid Digestion

Answer 4

1) Emulsification: Lipids split into tiny droplets by bile salts

2) Lipids hydrolysed by lipases which hydrolyse ester bonds in triglycerides to form fatty acids and monoglycerides

Question 5

Carbohydrate digestion

Answer 5

Amylase breaks down starch into maltose

Membrane-bound disaccharidases:

1) Maltase hydrolyses maltose into two glucose molecules.

2) Sucrase hydrolyses sucrose into glucose and fructose.

3) Lactase hydrolyses lactose into glucose and galactose.

Question 6

Co-transport with sodium ions

Answer 6

Used to absorb amino acids and monosaccharides

Sodium ions are actively transported out of the epithelial cell, creating a sodium ion gradient

Question 7

Digestion Definition

Answer 7

process in which large molecules are hydrolysed by enzymes to produce smaller molecules

Question 8

Absorption of lipids

Answer 8

Monoglycerides and fatty acids are insoluble in water so need to be packaged into micelles
Enter epithelial cells by diffusion

If longer chain fatty acids, can’t enter epithelial cells so
Packaged into chylomicrons which enter the lymphatic system and then eventually drain into the bloodstream later on near the heart