i have not even solved one paper 6 in my life so i cant do that.
sry
.
but i can explain the kidney thingy.
and how it works.
the biology by DG Mackean is very good for that part.
just learn even though if there is something extra
the capillary is called a glomerulus ( oh no i forgot spell)
so high pressure over there causes the contents to leak out into that tubule.
but only small things go out, such as glucose, water amino acids ... (if protein and all that goes out, then the kidney is malfunctioning i.e ther is a problem)
this part is called ultra filtration
now these substances travel down the tubule
and few substances get absorbed back into the blood, to adjust the blood concentration/
this is called selective reabsorbtion.
it is called bowmans capsule ( i think i spelt it right).
now the these substances travels down the renal tubule, collects in one place, pelvis and passes on to ureter