B2 Flashcards
What is the order in which food passes through the digestive system?
Mouth, oesophagus, stomach, small intestine, large intestine, rectum, anus
What is the function of the mouth in digestion?
To mechanically break up food into smaller pieces to increase surface area
What is the function of stomach acid?
To kill potentially pathogenic microorganisms in food
What is the function of the small intestine?
To absorb carbohydrates, lipids amino acids,vitamins and mineral ions from digested food
Give an adaptation of the small intestine to aid absorption of digested molecules.
Has structures called villi which increase surface area
Give an adaptation of the cells lining the small intestine to aid absorption of digested molecules.
Epithelial cells lining the villi have microvilli on their surface which further increase surface area
What is the function of the large intestine?
To absorb water from digested foods
What is the function of liver in digestion?
To produce bile, an emulsifying and neutralising substance
What is the function of the gall bladder?
To store bile until it can be released into the small intestine
What is the function of the rectum?
To store undigested material before excretion
What is an enzyme?
A protein which can catalyse a reaction without being used up itself
What is a substrate?
A molecule or an atom which is acted upon by an enzyme
How does an enzyme ‘recognise’ its specific substrate?
A complementary shaped ‘active site’ - A region on the enzyme which fits the substrate
Name two environmental conditions that can change an enzyme’s active sight.
pH (either higher or lower than optimum)
Higher than optimum temperature
What do carbohydrases break down and what do they produce?
Carbohydrates to simple sugar (e.g. amylase to simple sugars)
