You want to increase fruit diameter in tomatoes, and you want to estimate herita
ID: 279920 • Letter: Y
Question
You want to increase fruit diameter in tomatoes, and you want to estimate heritability for this trait. You measured the diameter of tomatoes in two inbred lines, the F1 hybrid between these two lines, and the F2 generation. The variance for tomato diameter in inbred line 1 was 4.2 cm2. The variance for tomato diameter in inbred line 2 was 3.8 cm2. The variance in the F1 generation was 4.4 cm2. The variance in the F2 generation was 36.1 cm2.
Calculate the values below. Type in only the numerical value and round all answers properly to 3 decimal digits.
Phenotypic Variance = Answer cm2
Environmental Variance = Answer cm2
Genetic Variance = Answer cm2
Broad-sense Heritability = Answer
Which cross is considered to be a backcross?
F2 x Inbred Line 2
F1 x F2
F1 x F1
F2 x F2
F1 x Inbred Line 2
Inbred Line 1 x Inbred Line 2
If broad-sense heritability for a trait is very high and narrow-sense heritability is very low, which of the following must be true?
Dominance variance must be high relative to phenotypic variance Additive variance must be high relative to phenotypic variance Environmental variance must be high relative to phenotypic variance
Explanation / Answer
1) Phenotypic variance is the variance of F2 generation. So, the value of phenotypic variance is 36.1 cm2.
2) Environmental variance is the variance of F1 generation. So, the value of environmental variance is 4.4 cm2.
3) Genetic variance is the difference between phenotypic and environmental variance,
= 36.1 - 4.4 cm2
= 31.7 cm2
4) Broad sense heritability is calculated by the formula,
Vg/ Vp, where Vg is genetic variance and Vp is phenotypic variance
= 31.7/ 36.1
= 0.878
5. Back crossing is defined as crossing the hybrid with one of its parents. So, F1 x F2 is considered as back cross.
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