DIGESTION & ABSORPTION

Question 1

Chemical digestion

Answer 1

Uses of enzymes to break down food

Question 2

Mechanical digestion

Answer 2

Physical movement t9 make foods smaller

Question 3

Digestive system

Answer 3

Ingestion - digestion -absorption -egestion

Question 4

What are hydroclorix acids used for

Answer 4

Kill bacteria
Changes optimum ph

Question 5

Digestion of starch

Answer 5

Food is broken up & mixed with saliva
Salivary amylase hydrolyse glycosidic bonds in starch forming maltose
Pancreatic amylase hydrolyse starch to maltose
Maltase hydrolysis maltose to glucose

Question 6

Amino acids / carbohydrate absorption

Answer 6

Na+ actively transported out of epitheicla cell into blood by Na+/K+ pump
Creating Na+ comcentration gradient
Nac & glucose enter by facilitated diffusion using slecific contransporter proteins
Na+ diffuse into cell down a concentration gradient
Glucose moves into cell against its concentration gradient
Glucose moves into blood by facilitated diffusion from a high con to a lo conc

Question 7

Protein digestion

Answer 7

In stomach , proteins hydrolysed by protease
Endopeptidases hydrolyse peptide bonds within polypeptide chain to produce smaller polypeptide chain to increase surface are for next enzyme for faster and more effiecient digestion
Exopeptidases hydrlyses peptide bond. At the terminal end of proteins removing 1 amino acid at a time
Exopeptidases rare specific : 1 group complementary to each side
Dipeptidases hydrolyse dipeptides jnto amino acids

Question 8

Lipid digestion

Answer 8

In stomach , lipids are turned into fat droplets
Bile is produced in the liver , stored in gall bladder and relased into small intestine with the food
Bile salts empulsify fat droplets into micelles which increases surface are of lipids for lipase action for a faster and more efficient digestion

Question 9

Lipids absorption

Answer 9

1. Triglycerides hydrolysed into glycerol, fatty acids and monoglycerides
2. Bile salts, fatty acids forms micelles
3. Micelles make fatty acids soluble in water and bring fatty acids to surface of epithelial cell membrane.
4. Fatty acids enter epithelial cell by simple diffusion
5. At smooth endoplasmic reticulum: fatty acids and glycerol are recombined to form triglycerides
6. At Golgi apparatus: triglycerides are modified proteins are added to form lipoproteins and packaged into vesicles
7. Chylomicrons are transported into lump vessel by exocytosis.

Question 10

What is digestion

Answer 10

Process at which larger molecules are hydrolysed by enzymes to form small molecules which are absorbed into blood then assimilated into biological molecules

Question 11

Co transport of glucose (3marks)

Answer 11

Sodium ions actively transported from the ileum cell to blood
Forms a diffusion gradient for sodium to enter cells from gut with glucose
Glucose enters by facilitated diffusion with sodium ions