Answer question fully as possible,justifying your answer with genetic diagram (with keys)as required.list all outcomes

Question

In a species of self fertilising plant,tall is dominant to short,and flower colour can be either red,blue,or in combination purple.Explain the genetics associated with crossing a homozygous tall plant with blue flowers,and a homozygous short plant with red flowers,going to and including the F2 generation.

Answer 1

Genetics of a plant cross (Height x Flower Color)

Assumptions :

-Height controlled by T( tall, dominant) and t (short,recessive)

-Flower color controlled by R (red ) and B (blue). RR= red, BB= blue, RB= purple ( incomplete dominance).

-Independent Assortment.

Parental cross :TTBB ( Tall,Blue) x tt RR ( Short,Red )

F1 Generation:

All offspring= TtRB----->Tall,Purple

F2 Generation :

Gametes : TR, TB, tR, tB -------> 4x4 Punnet Square

x TR TB tR tB

TR TTRR( Tall,Red ) TTRB( Tall,Purple ) TtRR( Tall,Red ) TtRB( Tall,Purple)

TB TTRB( Tall, Purple) TTBB( Tall,Blue) TtRB( Tall,Purple) TtBB(Tall,Blue)

tR TtRR (Tall,Red ) TtRB (Tall,Purple ) ttRR ( Short, Red ) ttRB (Short,Purple )

tB TtRB ( Tall,Purple) TtBB( Tall,Blue) tt RB( Short,purple) ttbb ( short,purple)

F2 Phenotypic ratios :

-Tall ,Red = 3/16 , Tall, purple =6/16, Tall , blue= 3/16, Short ,red = 1/16, Snort, Purple = 2/16, Short,Blue =1/16.

Collapsed ratios :

-Height only : 3 tall : I short

-Color only : 1 Red :2 purple :1 blue

EXplanation :

Height follows Simple Dominance (3:1). Color shows Incomplete Dominance (1:2:1) and Independent Assortment gives combined ratios as given above.