Question

Q. In water melon, red fruit colour (R) is dominant over cream fruit colour (r). A water melon plant homozygous for red fruits is crossed with a plant homozygous for cream fruits. The F1 are intercrossed to produce F2. (a) Give the genotypes and phenotypes of the parents, the F1, and the F2. (b) Give the genotypes and phenotypes of the offspring of a backcross between the F1, and the red fruit colour homozygous parent. (c) Give the genotypes and phenotypes of a backcross between the F1, and the cream fruit colour homozygous parent.

Answer 1

(a)F1 GEN will be all of red fruit colour ------ phenotype.
All will be heterozygous red fruit color------genotype

F2 GEN:- red fruit : cream fruit =3:1 -------phenotype
Homozygous red fruit: heterozygous red fruit: homozygous cream fruit=1:2:1

(b) Rr, Rr, RR, RR

(c) all are Rr



Hope it helps!!

Answer 2

a) parents - RR. × rr
(red) (cream)

F1 - all red with genotype Rr
now F1 intercrossed which is
Rr. × Rr
(red) (red)

F2- 1 RR 2 Rr 1 rr -genotypic ratio(1:2:1)
(red) (red) (cream) - phenotype ratio (3:1)


b)&(c) Back cross - when F1 crossed with either dominant or recessive parent
it is of 2 type
1. outcross= when F1 cross with dom. parent
Rr × RR
all dom. progeny peoduce
2. test cross = F1 cross with recessive parent
Rr × rr
then result is
Rr rr
(red) (cream)
gen. ratio =1:1
phenotypic ratio=1:1
no. of phenotype=2
no. of genotype =2
type of gametes =2

i hope it help !