exchange surfaces (p2) Flashcards
how many oxygen can haemoglobin bind to
4
what happens when one oxygen molecule binds to haemoglobin
molecule changes shape
makes it easier for the next oxygen molecule to bind
(positive cooperativity)
describe the bohr effect
p.pressure of CO2 rises
haemoglobin gives up oxygen more easily
what is the difference between fetal haemoglobin and adult haemoglobin
fetal has a higher affinity for oxygen
so it removes oxygen from maternal blood as they move past each other
what happens to CO2 in the red blood cell
converted into carbonic acid (H2CO3-) catalysed by carbonic anhydrase
carbonic acid dissociates to form hydrogen carbonate ions and protons
the h. carbonate ions move out the cell into the plasma
chloride ions move in maintaining the electrical balance of the cell (chloride shift)
what does haemoglobin also act as in the red blood cells
acts as a buffer
prevent changes in the pH by accepting free protons to form haemoglobinic acid
describe what happens in diastole
heart relaxes
atria and then ventricles fill with blood
why are the vascular bundles in the centre of the root
withstand tugging strains from stems and leaves being blown in the wind
what is the hydrostatic pressure in the leaf cells
1.5 MPa
how is continuous flow of water established in the plant
pull from water moving into the xylem and up the plant
+ cohesive forces between water
creates tension
how does water move into the xylem
ions pumped into the xylem
water moves by osmosis into the xylem from the endodermis through the symplast pathway
how does water enter the xylem
in the vascular bundle, water returns to apoplast pathway
how is root pressure established
pumping of ions into the xylem to produce water movement
what does root pressure do
push water up the xylem
(but it’s not the major factor)
