Date | May 2018 | Marks available | 3 | Reference code | 18M.2.SL.TZ1.3 |
Level | Standard level | Paper | Paper 2 | Time zone | Time zone 1 |
Command term | Distinguish | Question number | 3 | Adapted from | N/A |
Question
Using the Punnett grid, explain how two parents can have children with any of the different ABO blood groups.
Distinguish between the structure of arteries and the structure of veins.
Explain how cuts in the skin are sealed by blood clotting.
Markscheme
a. correct gametes of one parent as IA AND i in header line/column
AND
correct gametes of other parent as IB AND i in header column/line
b. correct corresponding genotypes in inner squares as IAIB, IAi, IBi, ii
c. corresponding phenotypes of children identified as AB, A, B and O
d. ratio of phenotypes is 1:1:1:1 OWTTE
Allow ECF.
a. arteries have thicker (muscular) walls/layer/tunica (media)
OR
veins have thinner (muscular) walls/layer/tunica (media)
b. arteries have no valves
OR
veins have valves
c. arteries have thicker elastic layer
OR
veins have thinner elastic layer
d. arteries have a smaller lumen/bore
OR
veins have a larger lumen/bore
Accept answers presented in a table.
a. clotting factors released from platelets
b. clotting process involves a cascade/series of reactions
c. produces thrombin
d. causes rapid conversion of fibrinogen into fibrin
e. fibrin makes a mesh to seal the wound OWTTE