Digestion and Absorption

Question 1

what happens during digestion

Answer 1

large biological molecules are hydrolysed into smaller molecules that can be absorbed across cell membranes

Question 2

which enzymes hydrolyse carbohydrates into monosaccharides

Answer 2

amylase
membrane bound disaccharides

Question 3

where is amylase produced

Answer 3

pancreas and salivary glands

Question 4

describe digestion of carbohydrates

Answer 4

• amylase hydrolyses polysaccharides into disaccharides (starch > maltose)
• glycosidic bonds are hydrolysed

Question 5

whats the role of the membrane bound disacharidases in the digestion of carbohydrates

Answer 5

• the glycosidic bonds between the disaccharides are hydrolysed to form monosaccharides
• completes in the ileum

Question 6

describe and explain the whole process of digesting carbohydrates

Answer 6

• salivary glands release amylase which hydrolyses the glycosidic bonds between the polysaccharide (starch) and forms disaccharides (maltose)
• disaccharide is swallowed and reaches the small intestine where membrane bound disaccharidases hydrolyses the disacharide into a monosaccharide.

Question 7

give two examples of membrane bound enzymes

Answer 7

sucrase
lactase

Question 8

what are three proteases that can digest proteins

Answer 8

enopeptidases
exopeptidases
membrane bound dipeptidases

Question 9

which peptide bonds do endopeptidases hydrolyse

Answer 9

the ones between amino acids in the middle of a polymer chain

Question 10

which peptide bonds do exopeptidases hydrolyse

Answer 10

the one between amino acids at the end of the chain

Question 11

what bond do membrane bound dipeptidases break

Answer 11

the peptide bonds between two amino acids

Question 12

where does protein digestion occur

Answer 12

starts in stomach
moves into the duodenum
finishes in ileum

Question 13

what enzyme breaks down lipids and where is it produced

Answer 13

lipase
produced in pancreas

Question 14

how does lipase digest lipids

Answer 14

hydrolyses the ester bond in triglycerides into monoglycerides and fatty acids

Question 15

what are bile salts and what do they do

Answer 15

produced in liver
they emulsify lipids to form tiny droplets called micelles which gives a larger SA

Question 16

describe and explain physical stage of lipid digestion

Answer 16

lipids coated in bile salts = emulsion
many small droplets of lipids = larger SA for faster hydrolysis by lipase enzyme

Question 17

describe chemical stage of lipid digestion

Answer 17

lipase enzyme hydrolyses the lipids into glycerol and fatty acids

Question 18

what are micelles

Answer 18

water soluble vesicles formed of fatty acids, glycerol and monoglycerides and bile salts

Question 19

what do micelles do

Answer 19

deliver fatty acids, glycerol and monoglycerides to the epithelial cells of the ileum for absorption

Question 20

which cells does the absorption of the products of digestion occur

Answer 20

cells lining the ileum

Question 21

how is the ileum adapted for efficient absorption

Answer 21

has villi and micro villi which increases the SA
thin walls which provides a short diffusion pathway
theres a network of capillaries to maintain. the concentration gradient

Question 22

by which method are monosaccharides and amino acids absorbed

Answer 22

co transport

Question 23

how are lipids absorbed

Answer 23

• digested by lipase into monoglycerides and fatty acids
• micelles are formed
• micelles go towards the ileum where the monoglycerides and fatty acids diffuse across the c.s.m to enter the cells of the epithelial cells
• this is due to the non-polar nature of them = lipid soluble
• once inside, they are modified back into triglycerides inside the golgi apparatus

Question 24

how are monosaccharides absorbed into the ileum

Answer 24

via active transport with sodium ions
> uses a co transporter protein