A-LevelBiologyHomeostasis9700/43 · May/June 2018 · Q1015 Marks
Describe the effect of a high blood concentration of ADH on the kidney.
- (a)Describe the effect of a high blood concentration of ADH on the kidney.[8]
- (b)Explain how glucagon brings about a rise in blood glucose concentration.[7]
Mark scheme
Marking points from the official mark scheme (May/June 2018). The mark or mark type is shown in brackets.
- 10(a) eight from:
- 1 ADH reaches (cells of) collecting duct ;
- 2 binds to receptor on cell surface membrane ;
- 3 enzyme-controlled reactions / enzyme cascade ;
- 4 (active) phosphorylase;
- 5 (which causes) vesicles with, aquaporins / water channels;
- 6 to, move to / fuse with, (cell surface) membrane ;
- 7 increase (membrane) permeability (to water) ;
- 8 (more) water moves out of collecting duct;
- 9 by osmosis / down water potential gradient ;
- 10 (then) into blood;
- 11 urine (more) concentrated / small volume of urine ;
- 12 AVP; e.g. role of loop of Henle in creating water potential gradient
- movement of urea increases water potential gradient
- 10(b) seven from:
- 1 (glucagon) acts as cell signalling molecule ;
- 2 binds to receptor on cell surface membrane ;
- 3 liver cell;
- 4 G-protein activated;
- 5 adenylyl cyclase activated;
- 6 formation of CAMP;
- 7 (which is) second messenger ;
- 8 enzyme-controlled reactions / enzyme cascade ;
- 9 signal amplified ;
- 10 glycogen hydrolysed to glucose / glycogenolysis ;
- 11 (glucose released) into blood ;
- 12 AVP; e.g. ref. to glucose exits via GLUT2 proteins / gluconeogenesis
Write your answer and get it marked
On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.
Sign up free →