Digestion and Absorption

Question 1

What is the primary function of the digestive system?

Answer 1

To break down food molecules and absorb water.

Question 2

What do digestive juices contain that facilitate digestion?

Answer 2

Hydrolytic enzymes and other molecules.

Question 3

What is the process by which large insoluble food molecules are converted into smaller soluble molecules?

Answer 3

Hydrolysis.

Question 4

What enzymes hydrolyse polypeptides and proteins into amino acids?

Answer 4

Proteases.

Question 5

What enzymes are responsible for hydrolysing carbohydrates into simple sugars?

Answer 5

Carbohydrases.

Question 6

Which enzymes hydrolyse fats into glycerol, fatty acids, and monoglycerides?

Answer 6

Lipases.

Question 7

What enzyme do salivary glands secrete?

Answer 7

Salivary Amylase.

Question 8

What is the role of gastric juice in the stomach?

Answer 8

It is acidic, kills microorganisms, and contains endopeptidases and exopeptidases.

Question 9

Where does the majority of nutrient absorption occur?

Answer 9

In the small intestine (ileum).

Question 10

What enzyme hydrolyses maltose to glucose in the small intestine?

Answer 10

Maltase.

Question 11

Complete the sentence: In mammals, cellulose is NOT hydrolysed because _______.

Answer 11

the enzyme cellulase is not produced.

Question 12

What are the products of starch digestion?

Answer 12

Maltose and glucose.

Question 13

Which two types of enzymes are involved in protein digestion?

Answer 13

Endopeptidases and exopeptidases.

Question 14

What is the function of dipeptidases?

Answer 14

To hydrolyse dipeptides into amino acids.

Question 15

What type of transport do monosaccharides use to cross the epithelial cell membrane?

Answer 15

Facilitated diffusion and co-transport.

Question 16

True or False: Glucose absorption requires ATP directly.

Answer 16

False.

Question 17

What is the role of bile in lipid digestion?

Answer 17

To emulsify fat droplets and increase the surface area for lipase action.

Question 18

What are micelles and their function in lipid absorption?

Answer 18

Micelles make fatty acids soluble in water and transport them to the epithelial cell surface.

Question 19

How are chylomicrons formed?

Answer 19

Triglycerides are modified and packaged with proteins at the Golgi apparatus.

Question 20

What is the outcome of lipid digestion in the small intestine?

Answer 20

Lipids are hydrolysed into glycerol, fatty acids, and monoglycerides.

Question 21

How are amino acids absorbed from the ileum into the blood?

Answer 21

By facilitated diffusion and co-transport using specific carrier proteins.

Question 22

Fill in the blank: Proteins are hydrolysed by _______.

Answer 22

Proteases.

Question 23

What happens to sodium ions if they are not actively transported out of the epithelial cell?

Answer 23

The concentration of sodium ions will rise in the cell.

Question 24

What is the order of the digestive system (process)?

Answer 24

Ingestion
Digestion
Absorption
Egestion

Question 25

What enzyme do salivary glands secrete and what does this hydrolyse?

Answer 25

Salivary glands –secretes salivary amylase which hydrolyses starch to maltose.

Question 26

What does the pancreas secrete?

Answer 26

Pancreatic juice containing: amylase endopeptidase exopeptidase lipase

Question 27

What has the small intestine been adapted for?

Answer 27

It has many ileum to provide a large surface area for the absorption of the products of digestion Maltase enzymes are embedded in the epithelial cell membrane of the small intestine to hydrolyse maltose to glucose, so it is available for rapid absorption

Question 28

Why is having maltase enzyemes embedded in the epithelial cell membrane of the small intestine a benefit?

Answer 28

To hydrolyse maltose to glucose so that it is available for rapid absorption

Question 29

Define digestion

Answer 29

A process in which large molecules are hydrolysed by enzymes into small molecules, which can be absorbed into the blood and then assimilated into biological molecules

Question 30

Describe the digestion of starch

Answer 30

1. Food enters the mouth and is mechanically digested 2. Salivary amylase hydrolyses glycosidic bonds in the starch to produce maltose 3. In the small intestine, pancreatic amylase hydrolyses more starch into maltose 4. Maltose is hydrolysed into glucose by maltase

Question 31

Where is maltase located?

Answer 31

The epithelial cell membrane of the ileum

Question 32

How are monosaccharides absorbed?

Answer 32

By facilitated diffusion and co-transport

Question 33

How are amino acids absorbed?

Answer 33

By facilitated diffusion and co-transport

Question 34

Describe how glucose is absorbed from the ilium into the blood

Answer 34

1. Sodium ions are actively transported out of epithelial cell into the blood by sodium potassium pump; 2. This creates a concentration gradient of Na+ 3. Na+ and glucose enter by facilitated diffusion using co-transport 4. Na+ diffuse into the cell down its concentration gradient. 5. Glucose moves into the cell against its concentration gradient 6. Glucose moves into the blood by facilitated diffusion

Question 35

Describe how amino acids are absorbed from the ilium into the blood

Answer 35

1. Sodium ions are actively transported out of epithelial cell into the blood by sodium potassium pump; 2. This creates a concentration gradient of Na+ 3. Na+ and amino acids enter by facilitated diffusion using co-transport 4. Na+ diffuse into the cell down its concentration gradient. 5. Amino acids move into the cell against its concentration gradient 6. Amino acids moves into the blood by facilitated diffusion

Question 36

What do epithelial cells contain a lot of, for more active transport?

Answer 36

Many mitochondria to produce a large amount of ATP

Question 37

Why can't some people hydrolyse lactose?

Answer 37

They do not produce lactase

Question 38

How does lactose and disaccharides lower water potential?

Answer 38

They are soluble

Question 39

Lactose and disaccharides are soluble, what does this mean?

Answer 39

They lower water potential

Question 40

Describe protein digestion

Answer 40

1. Proteins are hydrolysed by protease. 2. Endopeptidases hydrolyse the peptide bonds within the polypeptide chain. 3. This produces many smaller polypeptide chains and increases the surface area for the next enzyme. This makes digestion faster and more efficient. 4. Exopeptidases hydrolyse the peptide bonds at the terminal ends of the protein, removing one amino acid at a time. Amino acids and dipeptides are produced. 6. Then dipeptidases hydrolyse dipeptides into amino acids which can now be absorbed by facilitated diffusion, active transport and cotransport.

Question 41

What are exopeptidases?

Answer 41

Specific: one group are complementary to the N terminal end and another group are complementary to the C terminal end.

Question 42

Where are dipeptidases located?

Answer 42

embedded in the cell surface membrane of the epithelial cells

Question 43

Where are lipids digested?

Answer 43

ONLY within the lumen of the ileum

Question 44

Where is bile produced?

Answer 44

Liver

Question 45

Where is bile stored?

Answer 45

The gall bladder

Question 46

What does bile contain?

Answer 46

Bile salts, which emulsify fat droplets

Question 47

Why is it good that bile salts emulsify fat droplets?

Answer 47

It increases the surface area of the lipids for the action of lipases

Question 48

What do lipases hydrolyse lipids into?

Answer 48

Glycerol Fatty acids Monoglycerides

Question 49

Describe lipid digestion

Answer 49

1. Lipid droplets are mixed with bile salts to form smaller droplets; 2. Smaller droplets increase surface area for faster hydrolysis by lipase; 3. Triglycerides hydrolysed into glycerol, fatty acids and monoglycerides; 4. BILE SALTS, Glycerol and fatty acids form micelles;

Question 50

Describe lipid absorption

Answer 50

5. Micelles make Fatty acids soluble in water and bring Fatty acids to the surface of the epithelial cell membrane. 6. Fatty acids enter the epithelial cell by simple diffusion. 7. At the Smooth.E.R→Fatty acids, glycerol are recombined to form triglycerides. 8. At the golgi apparatus →Triglycerides are modified, proteins are added to form lipoproteins and packaged into vesicles. 9. Lipoproteins are transported into a lymph vessel by exocytosis. They then enter the blood.