digestion 3.3.3

Question 1

name components of digestive system

Answer 1

salivary glands
tongue
epiglottis
oesophagus
liver
stomach
gall bladder
pancreas
duodenum
ileum
colon
rectum
anus

Question 2

what does saliva consist of

Answer 2

mucin
amylase
mineral salts

Question 3

peristalsis definition

Answer 3

involuntary contraction or relaxation of muscles

Question 4

what happens in the oesophagus

Answer 4

peristalsis of the circular muscle contracts and relaxes to push food down

Question 5

what does the liver do

Answer 5

produces bile

Question 6

what does bile contain (and function of components)

Answer 6

bile salts - aids digestion of fats
mineral salts - neutralise stomach acid

Question 7

function of gall bladder

Answer 7

stores bile

Question 8

function of stomach

Answer 8

produces enzymes
stores and digests food

Question 9

pancreas function

Answer 9

produces pancreatic juices

Question 10

ileum structure and function

Answer 10

longest part of small intestine
enzymes produced in wall
inner walls have villi

Question 11

colon (large intestine) function

Answer 11

absorbs water (via osmosis)
absorbs mineral and vitamins

Question 12

function of duodenum (first section of small intestine)

Answer 12

receives secretions from the liver and pancreas
further digestion occurs

Question 13

physical breakdown of food

Answer 13

slicing and chewing action of the teeth
increases surface area for enzyme action
continues with churning action caused by contraction of muscles in the stomach wall

Question 14

chemical digestion of food

Answer 14

enzyme hydrolyse molecules into smaller soluble molecules

Question 15

why are multiple enzymes needed for molecules to be chemically digested

Answer 15

enzymes are specific so more than one is needed to hydrolyse a large molecule

one enzyme will hydrolyse a large molecule into sections and then the other will hydrolyse these sections into their monomers

Question 16

carbohydrases function

Answer 16

hydrolyse carbohydrates ultimately to monosaccharides

Question 17

lipases function

Answer 17

hydrolyse lipids into glycerol and fatty acids

Question 18

proteases function

Answer 18

hydrolyse proteins ultimately to amino acids

Question 19

starch digestion

Answer 19

salivary glands secrete salivary amylase
amylase hydrolyses starch into maltose
duodenum has pancreatic juices which contains pancreatic amylase which hydrolyses starch
peristalsis moves food along the intestine membrane bound maltase
hydrolyses maltose into alpha glucose

Question 20

what do the mineral salts in salvia do

Answer 20

maintain a pH 7

Question 21

what do disaccharidase enzymes do

Answer 21

hydrolyses disaccharides into monosaccharides

Question 22

3 disaccharidase enzymes

Answer 22

sucrase
lactase
maltase

Question 23

what does sucrase breakdown (and into what)

Answer 23

sucrose to glucose and fructose

Question 24

what does lactase breakdown

Answer 24

lactose to glucose and galactose

Question 25

what does maltase breakdown

Answer 25

maltose to alpha glucose

Question 26

which enzymes break down proteins

Answer 26

peptidases (proteases)

Question 27

what do endopeptases do

Answer 27

hydrolyse peptide bonds between amino acids in the central region of the molecule

Question 28

where are endopeptidases found

Answer 28

in the stomach

Question 29

what do exopeptidases do

Answer 29

hydrolyse the peptide bonds on the terminal amino acids of the peptide molecule to release dipeptidases and single amino acids

Question 30

where are exopeptidases found

Answer 30

the duodenum

Question 31

what do dipeptidases do

Answer 31

hydrolyse the bond between the dipeptide to release amino acids

Question 32

where are dipeptidases found

Answer 32

they are membrane bound found on epithelial cells lining the ileum

Question 33

what do lipases do

Answer 33

hydrolyse lipids

Question 34

where are lipases produced

Answer 34

the pancreas

Question 35

what do lipases do

Answer 35

hydrolyse the ester bond to form fatty acids and monoglycerides

Question 36

what is the structure of a monoglyceride

Answer 36

a glycerol with one fatty acid attached

Question 37

what does bile do

Answer 37

emulsifies large fat droplets to small droplets called micelles this increases the surface area of the lipids

Question 38

where are bile salts made

Answer 38

liver

Question 39

where are bile salts stored

Answer 39

gall bladder

Question 40

order of lipid digestion

Answer 40

bile emulsifies large lipid globules to small lipid globules lipase hydrolyses ester bond forms fatty acids and glycerol

Question 41

where are sucrase lactase and maltase made

Answer 41

ileum epithelial cells

Question 42

where does the absorption of hydrolysed products of digestion occur

Answer 42

in the ileum

Question 43

structure of ileum wall (4)

Answer 43

folded villi thin walls lined with epithelial cells

Question 44

adaptations of the ileum

Answer 44

villi increase surface area for diffusion thin wall reduces diffusion pathway blood vessels carry away absorbed material maintaining the gradient microvilli increase surface area for absorption

Question 45

where are microvilli

Answer 45

on the epithelial cells lining the villi on the ileum wall

Question 46

how are glucose and amino acids absorbed into the epithelial cell

Answer 46

co transport

Question 47

how are glucose and amino acids moved from the ileum epithelium cell to the blood

Answer 47

facilitated diffusion

Question 48

explain the transport of amino acids/glucose from the lumen of the ileum into the bloodstream (sodium potassium pump)

Answer 48

1 sodium ions transported out of epithelial cell membrane into the blood via the sodium potassium pump (ATP) 2 this maintains a low concentration of sodium ions inside the epithelial cell compared to the gut lumen 3 sodium ions diffuse down a concentration gradient from the lumen into the epithelial cell by facilitated diffusion 4 brings a glucose/amino acid molecule with it by co transport via carrier protein against concentration gradient 5 glucose/amino acids pass into the blood via facilitated diffusion

Question 49

Describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into lymph vessels (5 marks)

Answer 49

Micelles contain bile salts and fatty acids Maintain higher concentration of fatty acids to cell/lining of the ileum Fatty acids absorbed by diffusion Triglycerides formed in cells Vesicles move to cell membrane