Digestion and absorption

Question 1

Where is amylase produced?

Answer 1

Pancreas, salivary glands and small intestine

Question 2

What is the importance of digestion?

Answer 2

Hydrolyses large food molecules into smaller molecules
Which can move across cell membrane
And be absorbed into the blood

Question 3

Why are different enzymes needed to catalyse the breakdown of carbohydrates, proteins and lipids?

Answer 3

Enzymes are proteins with specific tertiary structures
Active site complementary to a specific substrate
Only specific substrate will bind to active site and form E-S complex

Question 4

Where is maltase produced?

Answer 4

(In the cell membrane of epithelial cells)
Small intestine

Question 5

Where is amylase secreted?

Answer 5

Mouth and small intestine

Question 6

What are the roles of the glands in the digestive system?

Answer 6

To produce digestive juices

Question 7

Name two types of glands in the digestive system

Answer 7

Pancreatic glands
Salivary glands

Question 8

What is the function of the small intestine in the digestive system?

Answer 8

It is where some digestion occurs and the absorption of soluble food also occurs

Question 9

What is the function of the stomach in the digestive system?

Answer 9

It is where digestion occurs.
It produces hydrochloric acid

Question 10

What is the role of the liver in the digestive system?

Answer 10

It produces bile

Question 11

What are enzymes?

Answer 11

Biological catalysts with a specific shape active site

Question 12

Where is lipase produced?

Answer 12

Pancreas and small intestine

Question 13

Where is lipase secreted?

Answer 13

The small intestine

Question 14

Where is protease produced?

Answer 14

Stomach, pancreas and small intestine

Question 15

Where is protease secreted?

Answer 15

Stomach and small intestine

Question 16

What is the role of bile in the digestive system?

Answer 16

Neutralises HCl (from stomach) to provide alkaline conditions in which small intestine enzymes work best
It emulsified the fats into smaller fat droplets giving a larger surface area for lipase to act on

Question 17

Where is bile produced?

Answer 17

Liver

Question 18

Where is bile stored?

Answer 18

Gall bladder

Question 19

What are proteins hydrolysed to?

Answer 19

Amino acids

Question 20

What is starch hydrolysed to?

Answer 20

alpha glucose

Question 21

What is fat hydrolysed to?

Answer 21

Fatty acids and glycerol
Monoglycerides

Question 22

Why can starch not be absorbed as easily?

Answer 22

It is a large, insoluble molecule

Question 23

What is starch first digested into?

Answer 23

Maltose

Question 24

What is maltose digested to?

Answer 24

Alpha glucose

Question 25

Explain how starch is hydrolysed to maltose

Answer 25

Amylase in the small intestine and mouth hydrolyses the glycosidic bonds

Question 26

Explain how maltose is hydrolysed to alpha glucose

Answer 26

Maltase (membrane bound disaccharidase) Hydrolyses glycosidic bond in maltose to produce alpha glucose

Question 27

Which monosaccharides is sucrose hydrolysed to?

Answer 27

Glucose Fructose

Question 28

Which monosaccharides is lactose hydrolysed to?

Answer 28

Glucose Galactose

Question 29

Explain co transport of glucose and sodium ions

Answer 29

Na+ actively transported out of epithelial cells into blood Establishes concentration gradient for Na+ into epithelial cells from lumen Na+ and glucose move by facilitated diffusion via co-transporter proteins into epithelial cell Glucose diffuses out of the cell into the blood by facilitated diffusion

Question 30

How is the small intestine adapted for digestion?

Answer 30

The lining Is folded into villi which give a large surface area The epithelial cells have microvilli which increase the surface area even more

Question 31

Explain how dipeptides are hydrolysed to amino acids

Answer 31

Dipeptidases in the cell surface membrane of epithelial cells Hydrolyse peptide bond between 2 amino acids

Question 32

Explain the steps in the digestion of a protein to a dipeptide

Answer 32

Endopeptidases hydrolyse peptide bonds within the protein Exopeptidases hydrolyse peptide bonds at the ends of the protein

Question 33

What is the difference in the co-transport of amino acids and the co-transport of glucose?

Answer 33

With glucose - Na+ are actively transported into the blood With amino acids- Na+ are actively transported into the ileum

Question 34

Describe how exopeptidases work

Answer 34

Hydrolyse peptide bonds at the ends of the protein Remove single terminal amino acids from proteins

Question 35

Explain how amino acids are absorbed

Answer 35

Na+ actively transported into the ileum from the epithelial cells Na+ and amino acids diffuse into cells via sodium-dependent transporter proteins

Question 36

Explain the role of bile in lipid digestion

Answer 36

Bile salts emulsify lipids Provide a larger surface area for lipase

Question 36

Where does lipid digestion occur?

Answer 36

The lumen of the small intestine

Question 37

Explain lipid digestion

Answer 37

In the small intestine lipase hydrolyses ester bonds Produces monoglycerides, fatty acids and glycerol Monoglycerides and fatty acids form micelles with bile salts

Question 38

Explain how the products of lipid digestion are absorbed

Answer 38

Micelles move monoglycerides and fatty acids to the epithelium Micelles constantly break up and reform, releasing the monoglycerides and fatty acids These diffuse across the cell membrane

Question 39

Explain why chylomicrons leave the cell by exocytosis

Answer 39

They are too large to leave by any other method

Question 40

Give an advantage of maltose being in the cell membrane and not secreted in pancreatic juice

Answer 40

It's a more effective way to absorb the products Enzymes not lost in gut contents

Question 41

Why would damage to the microvilli cause the amino acid concentration of the blood to decrease?

Answer 41

Decreases surface area of epithelial cells Fewer amino acid actively transported/ absorbed into epithelial cell