a. (i) Type of genetic cross: Dihybrid
(ii) Reason for answer: Two characters are involved in the cross/involves two characters separable in inheritance.
b. (i) Phenotype of F1: Tall and Red.
(ii) Genetic Diagram
Let T represent the gene for Tallness;
t represent the gene for Dwarfism;
R represent the gene for Red;
r represent the gene for White.
OR
Parental genotype TtRr X TtRr
| X | TR | Tr | tR | tr |
| TR | TTRRTallRed | TTRrTallRed | TtRRTallRed | TtRrTallRed |
| Tr | TTRrTallRed | TTrrTallWhite | TtRrTallRed | TtrrTallWhite |
| tR | TtRRTallRed | TtRrTallRed | ttRRDwarf Red | ttRrDwarfRed |
| tr | TtRrTallRed | TtrrTallWhite | ttRRDwarfRed | ttrrDwarfWhite |
Crosses of parental genotypes
Tall and Red - 9
Tall and White - 3
Dwarf and Red - 3
Dwarf and White - 1
Parental genotype
Parental gametes (TR, Tr, tR, tr) shown
Correct Crosses of parental gamete
Phenotypic ratio 9:3:3:1
(iii) Calculation of Tall and White flowers in F2
(3/16) x (160/1) = 30
