| In the XX-XY system, the _____ parent is heterogametic. | Father (male) |
| In birds, the sex determination system is _____; the _____ sex is heterogametic. | ZW-ZZ; female (ZW) |
| A male is _____ for X-linked genes because he has only one X chromosome. | Hemizygous |
| The karyotype of Down syndrome is _____. | 47, +21 (trisomy 21) |
| The karyotype of Turner syndrome is _____; the individual is _____. | 45, XO; female |
| The karyotype of Klinefelter syndrome is _____; the individual is _____ because of the _____ gene on the Y chromosome. | 47, XXY; male; SRY |
| Sickle cell anaemia results from a point mutation changing mRNA codon _____ from _____ to _____, replacing _____ acid with _____. | 6; GAG; GUG; glutamic; valine |
| Sickle cell anaemia is an _____ recessive disorder, caused by mutation in the _____ gene on chromosome _____. | autosomal; HBB; 11 |
| Alpha-thalassemia involves the _____ gene on chromosome _____. | HBA1/HBA2; 16 |
| Phenylketonuria is caused by deficiency of the enzyme _____, encoded by the _____ gene on chromosome _____. | phenylalanine hydroxylase; PAH; 12 |
| Haemophilia A is _____ recessive; it affects the _____ gene on the _____ chromosome. | X-linked; F8; X |
| Number of Barr bodies in a normal female = _____; in Turner = _____; in Klinefelter = _____. | 1; 0; 1 |
| In X-linked recessive pedigrees, affected daughters are rare because they require _____ from both parents. | the recessive X allele (Xa) |
| An affected father (Xh Y) passes _____ to all daughters and _____ to all sons. | Xh; Y |
| In a carrier female × normal male cross, P(haemophilic son) = _____; P(haemophilic child) = _____. | 1/2; 1/4 |
| The probability that an unaffected sibling of an autosomal recessive patient is a carrier = _____. | 2/3 |