3.2 Mass transport

Question 1

what products are formed from the hydrolysis of carbohydrates?

Answer 1

disaccharides then monosaccharides

Question 2

what products are formed from the hydrolysis of fats?

Answer 2

fatty acids and monoglycerides

Question 3

what products are formed from the hydrolysis of proteins?

Answer 3

amino acids

Question 4

where are digestive enzymes produced?

Answer 4

specialised cells in mammal digestive systems

Question 5

which enzyme catalyses the digestion of starch?

Answer 5

amylase

Question 6

which enzyme catalyses the digestion of lipids?

Answer 6

lipase

Question 7

which enzyme catalyses the digestion of proteins?

Answer 7

peptidases - endo and exo

Question 8

where is amylase produced and released?

Answer 8

produced by salivary glands and released in mouth. produced by pancreas and released in small intestine

Question 9

how does amylase work?

Answer 9

hydrolyses glycosidic bonds in starch

Question 10

what are membrane-bound disaccharidases?

Answer 10

enzymes attached to the cell membranes of epithelial cells lining the ileum

Question 11

what is the function of membrane-bound disaccharides?

Answer 11

break down disaccharides into monosaccharides through hydrolysis of glycosidic bonds

Question 12

which disaccharidase hydrolyses sucrose?

Answer 12

sucrase

Question 13

which disaccharidase hydrolyses maltose?

Answer 13

maltase

Question 14

which disaccharidase hydrolyses lactose?

Answer 14

lactase

Question 15

where is lipase produced and released?

Answer 15

produced by pancreas and released in small intestine

Question 16

how does lipase work?

Answer 16

hydrolyse ester bonds in lipids

Question 17

where are bile salts produced, stored and released?

Answer 17

produced in the liver, stored in the gall bladder, released in the small intestine

Question 18

what is the function of bile salts?

Answer 18

emulsify lipids into smaller droplets to increase surface area

Question 19

how are micelles formed?

Answer 19

monoglycerides and fatty acids attach to bile salts

Question 20

explain the process of lipid digestion [5]

Answer 20

1. bile salts emulsify lipids to form smaller droplets
2. surface area available for lipase to work on is increased
3. lipase hydrolyses ester bonds in lipid droplets
4. monoglycerides and fatty acids are produced
5. these stay attached to bile salts to form micelles

Question 21

what is the role of the oesophagus in the digestive system?

Answer 21

to carry food from the mouth to the stomach

Question 22

what is the role of the stomach in the digestive system?

Answer 22

stores and digests food using enzymes produced by glands in the inner layer

Question 23

what is the role of the ileum in the digestive system?

Answer 23

to digest food and absorb nutrients

Question 24

explain how the epithelial cells lining the small intestine are adapted for the absorption of glucose [6]

Answer 24

• microvilli provide a large surface area
• many mitochondria to produce ATP for active transport
• carrier proteins for active transport
• channel/carrier proteins for facilitated diffusion
• co-transport of sodium ions and glucose
• membrane-bound enzymes digest disaccharides and produce glucose

Question 25

what is the role of the large intestine in the digestive system?

Answer 25

to absorb water into the bloodstream

Question 26

what is the role of the salivary glands in the digestive system?

Answer 26

To secrete the enzyme amylase into the mouth, which hydrolyses starch into maltose

Question 27

what is the role of the pancreas in the digestive system?

Answer 27

To secrete pancreatic juice, which contains proteases to hydrolyse proteins, lipase to hydrolyse lipids, and amylase to hydrolyse starch

Question 28

Describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into lymph vessels [5]

Answer 28

• micelles contain bile salts, fatty acids and monoglycerides
• carry fatty acids and monoglycerides to ileum lining
• fatty acids and monoglycerides are absorbed by diffusion
• triglycerides reform
• chylomicron released via exocytosis