double circulation......

[hassam]

Use the information in Fig. 5.2 and Fig. 5.3 to suggest why the mammalian system is called a complete double circulation whilst that of the frog is called a partial double circulation.
Suggest why the system shown for the frog may be less effective at supplying the body tissues with oxygen.
ansers...???

 

[hassam]

why it is difficult to develop vaccine against HIV
HIV has a high mutation rate ;
contains RNA not DNA as genetic material ;
vaccine made will not be effective against different forms of virus ;
antigen / protein coat changes ;
hides in, T helper / T4 cells ;
AVP ; attenuated / live vaccine not safe to trial
this is MS...cn any1 explain me second point in the markscheme

 

[workinghard]

its hard 2 fig out whether u r askin a ques or tellin an ans or doing both!
from da fig wat i picked out was dat it is a D.C since the route through lungs and body is seperate ie each start and end at heart but do not really dross eachother
but thething v can c is dat only one artery leads 4m heart dat supplies to the lungs and the body so it is patial double circulation
the disadvantage is dat dere is mixing of oxygenated and deoxygenated bloods as a result of which dere is less efficient diffusion gradient and less efficient distribution
also if i hv 2 make a wild guess
i d say dat the supply wont be as effective to the body bcuz da pressure in the artery leeading to the body and the lungs is low!
i picked it up 4m da fact dat lungs is a delicate tissue andd bloob entering and leaving it is normally at lower tpressure than in normal systemic circulation
am i rite???????????

 

[workinghard]

i meant organ
lung is a delicate organ!

 

[Amna]

for the double circulation question...i think the frog's is called a partial double circulation because there's no closed loop between the lungs and the heart and another between the heart and the rest of the body... like it is in humans. in the frog it's more like deoxygenated blood from the rest of the body comes back into the heart along with the oxygenated blood from the lungs and they're pumped together to the rest of the body, and the lungs at the same time. it's less effiecient for supplying oxygen to body tissues cuz the oxygenated and deoxygenated bloods mix, so there's lower levels of HbO overall...