Question 18M.2.SL.TZ1.3
| Date | May 2018 | Marks available | [Maximum mark: 8] | Reference code | 18M.2.SL.TZ1.3 |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Distinguish, Explain | Question number | 3 | Adapted from | N/A |
Using the Punnett grid, explain how two parents can have children with any of the different ABO blood groups.
[3]
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.
Distinguish between the structure of arteries and the structure of veins.
[3]
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.
Explain how cuts in the skin are sealed by blood clotting.
[2]
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
