B3 Organisation and the digestive system Flashcards
paper 1
Name the five levels of organisation.
cells - tissues - organs - organ systems - organisms
What is a tissue?
group of cells with similar structures
What is an organ?
group of tissues working together to perform a specific function
What is the function of the liver in digestion?
produces bile, which neutralises hydrochloric acid from the stomach and emulsifies fat to form small droplets with a large surface area
What is the function of saliva in digestion?
lubrication to help swallowing - contains amylase to break down starch
Name three enzymes produced in the pancreas.
amylase, protease, lipase
What are enzymes?
protein molecules that catalyse specific reactions in organisms
Why are enzymes described as specific?
each enzyme only catalyses a specific reaction because the active site only fits together with certain substrates (lock and key)
Describe the function amylase?
to break down starch into glucose
Where is amylase produced?
salivary glands, pancreas and small intestine
Describe the function of proteases.
to break down proteins into amino acids
Where are proteases produced?
stomach, pancreas and small intestine
Describe the function of lipases.
to break down lipids into fatty acids and glycerol
Where are lipases produced?
pancreas and small intestine
What are the two factors that affect the rate of activity of an enzyme?
temperature
pH
what does denatured mean?
shape of an enzyme’s active site is changed by high temperatures or extreme pH, so it can no longer bind with the substrate
Describe the effect of temperature on enzyme activity.
as temperature increases, rate of reaction increases until it reaches optimum for enzyme activity - above this temp enzyme activity decreases and eventually stops
Describe the effect of pH on enzyme activity.
different enzymes have a different optimum pH at which their activity is greatest- a pH much lower or higher than this enzyme activity decreases and stops
Why do different enzymes have different optimum pHs?
different parts of the digestive system have very different pHs - the stomach is strongly acidic and the pH in the small intestine is close to neutral
What is an organ system?
a group of organs working together to perform a specific function
