[SPM Biology Inheritance]

How to do this question?
Answer is (P: Aa, Q: AA)
Is it possible for P to be AA?

20. Diagram 7 shows a family pedigree for the albino characteristic.
Rajah 7 menunjukkan pedigri suatu keluarga bagi ciri albino.
Diagram 7 / Rajah 7
Albinism is controlled by a pair of recessive alleles, aa. A is dominant over a. What is the genotype for P and Q ? Albinisme dikawal oleh sepasang alel resesif, aa. A adalah dominan terhadap a. Apakah genotip bagi P dan Q?

For generation I, since an albino male/female is involved, one of the parent will have the aa recessive alleles.

As a result, for generation II, all of the children can belong to either the aa trait (if P or Q is Aa) or the Aa trait. In the question, all generation II do not exhibit albinism, indicating that they all have the Aa trait. But this doesn’t rule out the possibility of ‘Aa’ in the parent (P/Q), hence this would imply that P and Q must be either Aa or AA.

Therefore, the possible answers are:

  1. P: AA , Q: AA
  2. P: Aa, Q: Aa
  3. P: AA, Q:Aa
  4. P: Aa, Q: AA

Any of the above combination can be the answer, let me see the MCQ options if possible.

Owhhh I see, ok thank you very much!! :blush: :grin: