A tall violet flowered plant (TTVV) is crossed with a dwarf white flowered plant (ttvv). When the F1 plants are self-pollinated, a total of 1600 F2 plants are produced. How many plants of F2 generation are similar to the original parents in terms of both genotype and phenotype?
A tall violet flowered plant (TTVV) is crossed with a dwarf white flowered plant (ttvv). When the F1 plants are self-pollinated, a total of 1600 F2 plants are produced. How many plants of F2 generation are similar to the original parents in terms of both genotype and phenotype?
The correct option is D 200
This is a typical dihybrid cross. Both original parents are homozygous, so two different types of gametes will be formed- (TV) and (tv) respectively. The F1 progenies will be heterozygous with the genotype TtVv. Four different gametes are formed by the F1 plants- (TV), (Tv), (tV), (tv). The genotype of the F2 progenies are worked out using the Punnett square below
As shown here genotype ratio of the F2 generation is 1:1:2:2:4:2:2:1:1.
And 1 homozygous dominant (TTVV) and 1 homozygous recessive (ttvv) progenies are produced, which are the genotypes of the original parent plants. Therefore 116th of the 1600 F2 progenies are homozygous dominant (TTVV), that is 116×1600=100 and 116×1600=100 are homozygous recessive (ttvv). 100 + 100 = 200. Thus a total of 200 F2 progenies have the genotype of the original parents.
200
This is a typical dihybrid cross. Both original parents are homozygous, so two different types of gametes will be formed- (TV) and (tv) respectively. The F1 progenies will be heterozygous with the genotype TtVv. Four different gametes are formed by the F1 plants- (TV), (Tv), (tV), (tv). The genotype of the F2 progenies are worked out using the Punnett square below
As shown here genotype ratio of the F2 generation is 1:1:2:2:4:2:2:1:1.
And 1 homozygous dominant (TTVV) and 1 homozygous recessive (ttvv) progenies are produced, which are the genotypes of the original parent plants. Therefore 116th of the 1600 F2 progenies are homozygous dominant (TTVV), that is 116×1600=100 and 116×1600=100 are homozygous recessive (ttvv). 100 + 100 = 200. Thus a total of 200 F2 progenies have the genotype of the original parents.
