This was the most unpopular question among the candidates. The few candidates that
attempted it did so poorly.
The expected answers are:
(a)(i) Codominance
Codominance occurs when both the alleles in an heterozygous individual are fully
expressed; that is both alleles exert their effects so that the hybrid has a phenotype;
that is different from what the parents exhibit.
(ii) Calculation of Individuals with Co dominant blood group
Mention of codominant blood group is AB
Evidence of Calculation
32 .8% of 250
OR
32.8 x 250
100
= 82 individuals/people
(iii) Total number of individuals that can donate blood to blood group B
The total number of individuals will be from groups B and O
- 14% of the population is Blood group B
14% of 250
OR
14 x 250
100
= 35 individuals/people
- 45.2% of the population is blood group O
45.2% of 250
45.2 x 250 = 113 individuals/people
100
- Total number of people = 113 of group O
35 of group B
148 individuals/people can donate blood to the
accident victim in B
OR
The Total number of individuals from (B and O) blood group B and O
= 148 people/individuals
(b) Crossing
OR
Punnet Square – scoring/ (Punnet Square)
