In: Biology
In a test cross of a double heterozygote, each of the recombinant type gametes occurs at a frequency of 15%. The expected frequency of each of the parental type gametes is
a) 15% b) 20% c) 35% d) 45% e) 50%
Ans:
C) 35%
Explanation:
double heterozygote test cross is given as under
Phenotypes Tall Round x Dwarf wrinkled
Genotypes TTRR x ttrr
Gametes TR, Tr, tR, tr tr
Genotypes and phenotypes of F2 population
| 
 TR (35%)  | 
 Tr (15%)  | 
 tR (15%)  | 
 tr (35%)  | 
|
| 
 tr  | 
 TtRr  | 
 Ttrr  | 
 ttRr  | 
 ttrr  | 
Phenotypes Tall Round Tall wrinkled dwarf Round dwarf wrinkled
Since frequency of each recombinant gametes = 15%
Recombinant gametes = Tr and tR
Therefore frequency of recombinant gametes is given under
Tr = 15%
tR = 15%
Parental gametes = TR and tr
Therefore frequency of parental gametes is given under
TR= 35%
Tr =35%