OESWTE: Digestion and absorption

Question 1

Where is amylase produced?

Answer 1

• Salivary glands
• Pancreas

Question 2

What disaccharide is starch made from?

Answer 2

Maltose

Question 3

Where does the digestion of lipids occur?

Answer 3

Small intestine

Question 4

Explain how lipids are digested:

Answer 4

• Lipids mix with bile salts and are emulsified
• Lipid micelles are hydrolysed by lipase.
• Fatty acids and monoglycerides are a product.

Question 5

Where is endopeptidase produced?

Answer 5

• Stomach
• Small intestine

Question 6

Where is dipeptidase produced?

Answer 6

• Stomach
• Small intestine
• Epithelial cell

Question 7

By what process are amino acids absorbed into the blood?

Answer 7

Co-transport

Question 8

By what process are monosaccharides absorbed into the blood?

Answer 8

Co-transport

Question 9

Where does absorption of nutrients occur in mammals?

Answer 9

Ileum

Question 10

Explain how the ileum is adapted for absorption:

Answer 10

• Ileum wall is covered in villi = thin walls = network of capillaries

Question 11

In a hydrolysis reaction what are carbohydrates broken down into?

Answer 11

Disaccharides then monosaccharides

Question 12

In a hydrolysis reaction what are lipids broken down into?

Answer 12

Fatty acids and monoglycerides

Question 13

In a hydrolysis reaction what are proteins broken down into?

Answer 13

Amino acids

Question 14

What does amylase digest?

Answer 14

Starch

Question 15

What is starch made up of?

Answer 15

Two polysaccharides each made from long chains of alpha-glucose molecules

Question 16

How does amylase digest starch?

Answer 16

• Catalyses hydrolysis reactions that break the glycosidic bonds
• Maltose is produced.

Question 17

Where does the pancreas release amylase to?

Answer 17

Small intestine.

Question 18

What are membrane-bound disaccharides?

Answer 18

Enzymes that are attached to the cell membranes of epithelial cells lining the ileum.

Question 19

What is the role of membrane-bound disaccharides?

Answer 19

Help to break down disaccharides into monosaccharides.

Question 20

How do membrane-bound disaccharides break down disaccharides into monosaccharides?

Answer 20

Hydrolyse glycosidic bonds.

Question 21

What does lipase digest?

Answer 21

Lipids

Question 22

How does lipase digest lipids?

Answer 22

Ester bonds are hydrolysed.

Question 23

Where is lipase produced?

Answer 23

Pancreas

Question 24

Where are bile salts produced?

Answer 24

Liver

Question 25

What is the role of bile salts?

Answer 25

Emulsify lipids

Question 26

How do lipids being emulsified allow for faster digestion?

Answer 26

Formation of micelles greatly increases the surface area of lipid that the lipase can digest.

Question 27

Role of endopeptidases:

Answer 27

Hydrolyse peptide bonds and single amino acids at the end of protein molecules.

Question 28

What are dipeptideases?

Answer 28

Exopeptidases that work specifically on dipeptides.

Question 29

Role of dipeptidases:

Answer 29

Seperate the two amino acids that make up a dipeptide by hydrolysing the peptide bond between them.

Question 30

Where are dipeptidases often located?

Answer 30

Cell-surface membrane of the epithelial cells in the small intestine.

Question 31

How is glucose absorbed across the ileum epithelium into the bloodstream?

Answer 31

Absorbed by active transport with sodium ions via a co-transporter protein.

Question 32

How do micelles help to move monoglycerides and fatty acids towards the epithelium?

Answer 32

• Micelles break up and reform,
• Releases monoglycerides and fatty acids, allowing them to be absorbed.

Question 33

Why can monoglycerides and fatty acids diffuse directly across the epithelial cell membrane?

Answer 33

They are lipid-soluble.

Question 34

How are proteins absorbed across the ileum epithelium into the bloodstream?

Answer 34

• Sodium ions are actively transported out of the epithelial cells into the ileum.
• They then diffuse back into epithelial cells through sodium-dependent transporter proteins, carrying the amino acids with them.