Theory question 104
Mendelian Inheritance(a) A child belongs to blood group O and the mother belongs to group B. With the aid of a genetic cross, state the possible blood groups of the father. (b)(i) Name two forms of adaptive communication in animals. (ii) State two reasons why organisms communicate with one another.
Show the model answer
(a) The child is OO, so the mother must be BO and the father must give an O allele. The father can be AO, BO or OO.
Crosses: BO × AO → AB, BO, AO, OO; BO × BO → BB, BO, BO, OO; BO × OO → BO, BO, OO, OO. Each cross can give an OO child.
So the father's blood group could be A (AO), B (BO) or O (OO), but not AB.
Diagram must show parents, gametes, offspring.
(b)(i) Any two: sound (calls, songs, chirping); visual signals (colour, display, dances, body posture); chemical signals (pheromones, scent marking); touch (tactile).
(ii) Any two: to attract a mate; to warn of danger; to mark territory; to show where food is; to keep a group together; to identify members of the same species or colony; to frighten enemies.
The child's O allele must come from both parents, so the father cannot be AB.