Question

explain dihybrid cross and monohybrid cross with checkerboard

Answer 1

Mono hybrid cross having one pair of trait whereas dihybrid cross having two pair of traits.
Example:
Monohybrid-yellow flower and green flower.
Dihybrid-Round yellow and wrinkled green

Answer 2

Dihybrid cross is a cross between two different lines/genes that differ in two observed traits. In the Mendelian sense, between the alleles of both these loci there is a relationship of complete dominance - recessive.
Phenotype :-                        

Yellow Round  = 9/16
Yellow wrinkled = 3/16
Green Round = 3/16

Thus phenotypic Ratio = 9 : 3 : 3 : 1

Genotype:-

Homozygous yellow &Homozygous Round-YYRR = 1
Homozygous yellow &Heterozygous Round-YYRr = 2
Heterozygous yellow &Homozygous Round-YyRR = 2
Heterozygous yellow & Heterozygous Round-YyRr =4
Homozygous yellow& Homozygous wrinkled–YYrr = 1
Heterozygous yellow &Homozygous wrinkled-Yyrr = 2
Homozygous Green &Homozygous Round-yyRR = 1
Homozygous Green & Heterozygous Round-yyRr = 2
Homozygous Green & Homozygous wrinkled-yyrr = 1

Thus genotypic Ratio =1:2:2:4:1:2:1:2:1



A monohybrid cross is a mating between individuals who have different alleles at one genetic locus of interest. The character(s) being studied in a monohybrid cross are governed by two alleles for a single locus.
TT . tt
\ /
Tt
TT -TALL CHARACTER
tt - dwarf character
Tt - monohybrid cross...
phenotype ratio -3:1
genotype ratio -1:2:1