Question

In watermelons long and striped fruit characters dominate round and solid color characters. What are that genotypes of the parents in the following crosses?

A) round striped X long striped gives 3 long striped,1 long solid, 1 round striped and 1 round solid.

B) long solid X long striped gives 1 long striped, 1 long solid, 1 round striped and 1 round solid.

C) long striped X Long solid gives all long half striped, half solid.

D) Round solid X long striped gives all long striped

E) Round solid X Long striped gives 10 long solid, 11 long striped, 10 round solid and 9 round striped

Answer 1

let the alleles be L-long, l-round, S- striped, s- solid.

A) round striped X long striped gives 3 long striped,1 long solid, 1 round striped and 1 round solid.

all four phenotypes are possible

so genotype of round striped-llSs ( it has to have s allele so that it can pass s allele to the progeny, so that ss progenies are possible)

genotype of the long, striped is LlSs ( both recessive alleles has to be present, so they can have progenies with recessive phenotype)

	LS	Ls	lS	ls
lS	LlSS (long, striped)	LlSs (long, striped)	llSS ( round, striped)	llSs ( round, striped)
ls	LlSs (long, striped)	Llss ( long, solid)	llSs ( round, striped)	llss ( round, solid)

B) long solid X long striped gives 1 long striped, 1 long solid, 1 round striped and 1 round solid.

all four phenotypes are possible

the genotype of long solid is Llss ( it is heterozygous at the L locus so that they can produce gamete with l allele, then only it is possible to have ll ( round) progeny)

the genotype of long striped is LlSs, it has to have recessive alleles for both genes then only it is possible to produce ls gamete with fuse with ls gamete from the other parent to get round, solid progeny.

C) C) long striped X Long solid gives all long half striped, half solid.

all progenies are long so one of the long parent is homozygous dominant

genotype of long, striped is LLSs or LlSs

genotype of the long solid is Llss or LLss

( 50% of the progeny are solid and 50% are striped, so the striped parent is Ss and the solid parent is ss)

D) Round solid X long striped gives all long striped

genotype of round solid is llss, genotype of long striped is LLSS, so that all progenies are long , striped.

E) Round solid X Long striped

all four phenotypes are possible

genotype of round solid is llss.

genotype of long, striped is LlSs so that four different gametes can be produced Ls, LS, lS, ls, so that all four phenotypes are possible.

	LS	Ls	lS	ls
Ls	LLSs	LLss	LlSs	Ll
ls	LlSs	Llss	LlSs