23. In rabbits, short hair is due to a dominant allele, S, long hair to its rece
ID: 85244 • Letter: 2
Question
23. In rabbits, short hair is due to a dominant allele, S, long hair to its recessive allele, s. Black hair is due to a dominant allele, B, and white hair to its recessive allele, b. When two rabbits were crossed, they produced 2,518 short-haired, black and 817 long- haired, black offspring. What are the probable genotypes of the parents? 24. In humans, the condition for normal blood clotting dominates hemophilia. Both alleles are sex- linked to the X chromosome. Two parents produced daughters who are all carriers and sons who are all normal. What are the probable genotypes of the parents? 25. In humans, deafness is due to a homozygous condition of either or both recessive alle les d and e. Both dominant alleles D and E are needed for normal hearing. Two deaf people marry and produce offspring who all have normal hearing. What are the probable genotypes of the children and parents?Explanation / Answer
Short hair = S
Long hair=s
Black hair= B
White hair=b
Short haired, black=2518
Long haired black=817
ratio= 2518/817= 3:1
The genotypes of the parents
SsBB x SsBB
Gametes= SB, sB
SB
sB
SB
SSBB (Short haired, black)
SsBB (Short haired, black)
sB
SsBB (Short haired, black)
ssBB (Long haired black)
(24)
Genotype of parents
XX (female) x XhY (Male)
All females are carriers
XhX, XhX, XY, XY
SB
sB
SB
SSBB (Short haired, black)
SsBB (Short haired, black)
sB
SsBB (Short haired, black)
ssBB (Long haired black)