Digestion

Question 1

Define digestion

Answer 1

Enzymes break down large complex insoluble molecules into small simple molecules so they can be digested easier

Question 2

Define ingestion

Answer 2

Food taken in by the mouth

Question 3

Define absorption

Answer 3

Products of digestion are absorbed through the lining of the intestine

Question 4

Define assimilation

Answer 4

Uptake of nutrients by cells and their use in the cells

Question 5

Define Egestion

Answer 5

Removal of faeces containing undigested food, bacteria, enzymes and cells from the intestine lining

Question 6

What order does food go through the human body

Answer 6

Mouth
salivary gland
oesophagus
Stomach
liver
gall bladder
pancreas
duodenum
ileum
large intestine
appendix
rectum

Question 7

Define mechanical digestion

Answer 7

Large pieces of food can be broken down into smaller pieces using body structures such as teeth, stomach and muscles to increases SA

Question 8

Describe the breakdown of starch

Answer 8

Starch is hydrolysed into maltose by salivary gland amylase in the mouth and prancreatic amylase in the small intestine

Question 9

Describe the breakdown of maltose

Answer 9

Maltose is hydrolysed into glucose by maltase enzymes embedded in microvilli of intestinal epithelial cells

Question 10

Describe the breakdown of protein

Answer 10

Protein is hydrolysed by protease into polypeptides

Polypeptides are hydrolysed by protease to dipeptides

Dipeptides are hydrolysed by dipeptidases into AAs

Question 11

3 types of protease enzymes

Answer 11

Endopeptidases, exopeptidases and dipeptides

Question 12

Describe what endopeptidases do

Answer 12

Break bonds in the middle of the polypeptide to produce shorter polypeptides

Question 13

Describe what exopeptidases do

Answer 13

Break bonds at the end of the polypeptides

Question 14

Describe what dipeptides do

Answer 14

Break dipeptides down into AAs

Question 15

Where are amino acids absorbed

Answer 15

Cells lining the ileum of the Small intestine

Question 16

What do bile salts do

Answer 16

Emulsifies lipids to increase SA for pancreatic lipids

associate with monoglycerides and cholesterol to form micelles

Question 17

What enzyme acts on lipids

Answer 17

Lipase

Question 18

What are lipids hydrolysed to

Answer 18

Fatty acids by lipase

Question 19

Describe lipid digestion

Answer 19

Lipids are emulsified by bile salts in order to increase surface area

They are then hydrolysed into fatty acids and glycerol

fatty acids and monoglycerides are not very soluble in water so its hard to carry them to the villi

Question 20

Describe the absorption of lipids

Answer 20

micelles breakdown into fatty acids and monoglycerides which diffuse through the cell mebrane

in the endoplasmic reticulum monoglycerides and fatty acids are used to reform triglycerides

Next they go to the golgi body where triglycerides are packaged with protein and cholesterol into chylomicrons

chylomicrons move to and fuse with the cell membrane to release triglycerides into the lacteals by exocytosis

chylomicrons pass via lymphatic vessels into the blood stream

Question 21

Explain how cells lining the ileum of the mammals absorb glucose by co transport with sodium

Answer 21

Sodium ions actively transported from ileum cell to blood

This maintains the concentration gradient for sodium to enter the cells from gut.

Glucose enters by facilitated diffusion with sodium ions

Question 22

Describe how proteins are digested in the human gut

Answer 22

Hydrolysis of peptide bonds.

Endopeptidases break polypeptides into smaller pieces

Exopeptidases remove terminal amino acids

Dipeptidases hydrolyse dipeptides to amino acids

Question 23

What two enzymes are required for the complete breakdown of starch

Answer 23

amylase and maltase

Question 24

Describe how digestion of starch in the human gut would lead to an increase in glucose in the blood

Answer 24

Starch hydrolysed by maltase and amylase

Producing glucose

Glucose molecules small enough to cross the gut wall into the bloodq

Question 25

Suggest a method in order to estimate the concentration of glucose in a solution to turn brick red

Answer 25

Time how long it takes to go brick red

weigh the precipitate

Question 26

Why would pH increase when lipase is added to milk

Answer 26

As fatty acids are produced

Question 27

Why are the combined use of endopeptidase and exopeptidase more efficient than just one

Answer 27

endopeptidase hydrolyses internal peptide bonds

exopeptidase hydrolyse external peptide bonds

more ends increase surface area

Question 28

What would the addition of a respiratory inhibitor prevent the absorption of Amino Acids

Answer 28

Less ATP produced so no active transport
Sodium not moved out of the cell
No diffusion gradient for sodium to move into the cell with amino acids1

Question 29

Explain how epithelial cells that line the small intestine are adapted for the absorption of glucose

Answer 29

Microvilli provide a large SA

Have large amounts of mitochondria to produce ATP for active transport

Contains Carrier proteins for active transport and facilitate diffusion