exchange surfaces Flashcards
the curve is S shaped, this shows how initially it is hard for oxygen to bind with the first subunit of Hb. the middle section of the curve has a steeper gradient because once one oxygen has bound the Hb changes shape so that it is easier for more oxygen molecules to bind (cooperative binding).
the curve levels off at the top because once three oxygen molecules have binded with Hb it is less likely that a fourth molecule will be able to bind to the empty space.
the fetal Hb is always above the adult Hb because fetal Hb has a higher affinity for oxygen then the adult Hb does. this means that the fetus can obtain oxygen by binding with the mothers Hb.
what is the hearts stroke volume
The volume of blood pumped out of the left ventricle during each systolic cardiac contraction.
if the hearts rate decreases the stoke volume must increase in order to maintain the same cardiac output.
give the equation that links heart rate, cardiac output and stroke volume
cardiac output = heart rate x stroke volume
what does tachycardia mean
a fast heart rate
what is atrial fibrillation
lack of synchronisation between the atria and the ventricle
how are hydrophytic plants adapted for gas exchnage
stomata is on the upper dies to allow gas exchnage in the air away from water
the leaf is full of spongey air spaces so that its never too far from gas molecules and also for buoyancy
thin leaves so a short diffusion pathway
what does a potometer consist of and how does it work
a capillary tube filled with water from a revisor, one end is open for the introduction of air and one end sealed onto a plant shoot.
it should be set up underwater and the root should be cut underwater
it works by introducing a single air bubble into the capillary tube and you must measure the movement of the bubble - water follows behind in a continuous column.
how does sucrose enter the sieve tube by active loading
companion cells contain lots of mitochondria which produces ATP to actively transport H+ ions out of sieve tube and set up a conc gradient. due to the conc gradient H+ ions diffuse back into the sieve tube by facilitated diffusion carry sucrose molecules with the by cotransport. as conc of sucrose builds up in companion cells sucrose diffuses into sieve tubes through plasmodesmata because of conc gradient.
