1. Digestion and absorption

Question 1

amylase

1. what conversion does it catalyse?
2. this involves the hydrolysis of what bonds?
3. where is amylase produced and released?

Answer 1

1. conversion of starch (polysaccharide) into smaller sugar maltose (disaccharide)
2. glycosidic bonds
3. salivary glands - mouth
   pancreas - small intestine

Question 2

Membrane bound disaccharidases

1. where are they attached?
2. what do they break down?

Answer 2

1. cell membranes of epithelial cells of iluem (final part of small intestine)
2. disaccharides into monosaccharides

Question 3

Carbohydrates are broken down by what digestive enzymes

Answer 3

enzymes - amylase and membrane-bound disaccharidases

Question 4

glucose + glucose =

Answer 4

maltose

Question 5

glucose + fructose =

Answer 5

sucrose

Question 6

glucose + galactose =

Answer 6

lactose

Question 7

Membrane bound disaccharidases

1. name of disaccharidase that breaks down maltose (into glucose + glucose)
2. name of disaccharidase that breaks down sucrose (into fructose + glucose
3. name of disaccharidase that breaks down lactose (into glucos + galactose)

Answer 7

1. maltase
2. sucrase
   3 lactase

Question 8

what are lipids broken down by

Answer 8

enzyme - Lipase (with the help of bile salts)

Question 9

what is a monoglyceride made up of

Answer 9

glycerol molecule with 1 fatty acid attached

Question 10

Lipase

1. what conversion does it catalyse
2. what bonds are hydrolysed
3. where are they made
4. where do they work

Answer 10

1. breakdown of lipids into monoglycerides and fatty acids
2. ester bonds
3. pancreas
4. small intestine

Question 11

Bile salts

1. where are they produced?
2. what do they do?
3. how is this beneficial?
4. monoglycerides and fatty acids stick with bile salts to form tiny structures called

Answer 11

1. liver
2. emulsify lipids (cause lipids to form small droplets)
3. several small lipid droplets have a bigger surface area than single large droplet = increased surface area for lipase to work on and faster hydrolysis
4. micelles

Question 12

why are digestive enzymes used to break down biological molecules in food

Answer 12

large biological molecules too large to cross cell membranes (cant be absorbed into blood)
smaller molecules broken down by digestive enzymes can

Question 13

what are proteins broken down by

Answer 13

endopeptidases

exopeptidases

Question 14

endopeptidases

1. what bonds to they hydrolyse
2. e.g.s Trypsin and chymotrypsin - where are they made and where are they secreted
3. e.g. pepsin - where is it released and what is it released by
4. pepsin only works in what conditions

Answer 14

1. peptide bonds within a protein
2. pancreas. released in small intestine
3. stomach and released by cells in stomach lining
4. acidic (provided by HCl in stomach)

Question 15

exopeptidase

1. what bonds do they hydrolyse
2. e.g. dipeptidases work specifically on what
3. e.g. dipeptidases where are they located?

Answer 15

1. bonds at the end of protein molecules (remove single amino acids from proteins)
2. dipeptides (seperate 2 amino acids by hydrolysing peptide bond)
3. cell surface membrane of epithelial cells in the smll intestine

Question 16

how is glucose amino acids and galactose absorbed

Answer 16

by active transport with sodium ions via a co-transporter protein

Question 17

monosaccharides

how is fructose absorbed

Answer 17

facilitated diffusion through a transporter protein (different to the one glucose and galactose go through)

Question 18

how are monoglycerides and fatty acids absorbed

Answer 18

1. micelles move them towards epithelium
2. micelles constantly break up and reform = release lipids allowing them to be absorbed
3. lipid-soluble = diffuse directly across epithelial cell membrane

Question 19

where are the products of digestion absorbed

Answer 19

across iluem epithelium and into bloodstream