Answer:
a. 1:1
b. 25%
c. Dobby can give blood to Harry, but Harry cannot give blood to Dobby.
Explanation:
a. Type O blood is recessive to type A blood and type B blood.
A B
O AO BO
O AO BO
According to the Punnett square, 50% of the offspring will have the AO genotype and 50% will have the BO genotype (1/2=50%). This means 50% will have type A blood and 50% will have type B blood, as the alleles for type A and type B blood are dominant over the allele for type O blood.
b. The male house elf's genotype is AO. If his mother was type O, then she only had the type O alleles to pass down to him, so he had to inherit one. The female house elf's genotype is BO. Her mother had to have the genotype AO. This is the only way the female would have inherited type B blood. If her mother had the AA genotype, then she would've had type AA or AB blood.
B O
A AB AO
O BO OO
According to the Punnett square, their offspring have a 25% chance of displaying any of the four blood types (1/4=25%).
c. Dobby has type A blood and Harry has type AB blood. This means that Dobby can give blood to Harry, as Harry has A antigens. However, Harry cannot give to Dobby because Dobby doesn't have B antigens, so he would experience an incompatibility reaction.
