Biology · Oct / Nov 2025 · Paper 41 · Question 2

letter on Fig. 6.1 name of the blood

carries

vessel

oxygenated blood

A

pulmonary artery

no

B

aorta

yes

C

hepatic portal vein no

D

renal vein

no

;;;;

name: valve ;

function: prevents back flow of blood / AW ;

any two from:

(only) two chambers ;

no, septum / left and right sides / AW ;

fewer valves ;

heart (chamber) walls of similar thickness (to each other) ;

fewer blood vessels (going to and from the heart) ;

any four from:

1

blood is pumped to the lungs then to the body / blood goes through the heart twice in one complete journey / double circulation ; 2

oxygenated and deoxygenated blood, are kept separate / do not mix / separated by septum ;

3

efficient, supply of blood / glucose / oxygen / nutrients (to, the body / AW) ;

4

efficient, removal / carbon dioxide / urea / lactic acid (from, body / AW); 5

provides high(er) pressure (in body) ;

6

which allow a high, metabolic rate / rate of respiration ;

7

which allows filtration in kidneys (for excretion) ;

8

low(er) pressure in, pulmonary, artery / circuit / AW ;

9

to prevent damage to (capillaries in the) lungs ;

10 allow more time for, gas exchange / absorption of oxygen ; 11 AVP ;

red blood cell ;

actual size = image size ÷ magnification ;

31.5 (µm) ;