Biology Y10 Digestive System Flashcards
purpose of the digestive system
breaks down food into a soluble form for absorption into the bloodstream
function of mouth
teeth mechanically break down food, large surface area for enzyme action
function of oesophagus
connects mouth and stomach, peristalsis pushes food bolus along
function of stomach
churns food to break down further and mix it, releases proteases and hydrochloric acid
function of small intestines
soluble food molecules absorbed into blood, villi increase surface area
function of large intestines
absorb water, form faeces
function of gut flora
breaks down substances, supplies essential nutrients, synthesises vitamin K, competes with harmful bacteria
function of rectum
store faeces
function of anus
control opening of the body
function of salivary glands
produce amylase, lubricate food bolus
function of liver
produces bile to emusify fats, neutralises stomach acid
function of gall bladder
stores bile for release
function of pancreas
produces enzymes
where is amylase produced
salivary glands, pancreas, small intestines
where is protease produced
stomach, pancreas, small intestines
where is lipase produced
pancreas
where does amylase act
mouth, small intestine
where does protease act
stomach, small intestine
where does lipase act
small intestine
what does amylase digest into what
starch -> glucose
what does protease digest into what
proteins -> amino acids
what does lipase digest into what
lipids -> 3 fatty acids and glycerol
what pH is the stomach
1.5-2
what pH does amylase work best at
~7
what pH does protease work best at
~1.6
what pH does lipase work best at
~8
how does the stomach protect itself from the hydrochloric acid
has a thick mucus lining
how to test for starch
iodine test
how to test for sugar
benedict’s test
how to test for lipids
emulsion test (ethanol)
how to test for protein
biuret test
what colour is iodine test before and after a positive result
orange-brown -> blue-black
what colour is benedict’s test before and after a positive result
light blue -> green to brick-red
what colour is emulsion test before and after a positive result
colourless -> cloudy emulsion
what colour is biuret test before and after a positive result
blue -> lilac
what are enzymes
large protein molecules folded to produce a unique shape (also biological catalyst)
what is an enzyme made of
amino acids
with what kind of substrate can an enzyme combine
complementary
what is the lock and key theory
the enzyme has a specific shape that perfectly matches the sustrate
what is a denatured enzyme
an enzyme whose shape has been distorted
how can denaturing happen
temperature and pH
what happens to an enzyme at low temperature
little kinetic energy = few collisions
what happens to an enzyme at optimum temperature
the most successful collisions
what happens to an enzyme at above optimum temperature
the active site deforms and hte enzyme begins to denature
what happens to an enzyme at optimum pH
most successful collisions
what happens to an enzyme at non-optimum pH
denatured = few successful collisions
what happens to an enzyme at extreme pH
denatured = no activity
what is metabolism
sum of all the reactions in a cell or organism
what types of reactions do enzymes speed up
synthesis (small thing -> big things), changing one molecule to another and breaking down larger molecules into smaller ones
what is glucose used for
fuel for respiration, to release energy
what are amino acids used for
building new proteins for growth and repair, enzymes and antibodies
what are glycerol and fatty acids used for
rebuilding lipids for energy store, insulation, protecting organs and new cell membranes and hormones
what is optimum temperature for enzymes in humans
~37°C
how to do iodine test
add a drop of sample and a drop of iodine and record changes in appearance
how to do biuret test
add a drop of sample and a drop of biuret solution and record changes in appearance
how to do benedict’s test
get test tubes, put samples in each, put benedict’s solution in each, heat up to 85°C for five minutes and record changes in appearance
how to do emulsion test
add sample to test tube, add ethanol to the test tube and mix, have water in another test tube, pour ethanol mix into water, record changes in appearance
