In a cross of two pure-breeding lines of tomatoes producing different fruit size
ID: 44415 • Letter: I
Question
In a cross of two pure-breeding lines of tomatoes producing different fruit sizes, the variance in grams (g) of fruit weight in the F1 is 2.00 g, and the variance among the F2 is 5.90 g.
1. Determine the geneti? variance VG for the trait. (Express your answer using three significant figures.)
2. Determine the environmental variance VE for the trait. (Express your answer using three significant figures.)
3. Determine the broad sense heritability of the trait. (Express your answer using three significant figures.)
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Explanation / Answer
2. When two pure-breeding lines of tomatoes are selected for cross any variation among these individuals population will be due to their genetic variation. The F1 generation obtained on crossing these pure-breeding lines will be genetically identical and hence any phenotypic variation observed will be due to environmental variation VE. Hence environmental variance (VE) will be equal to the F1 phenotypic variance 2.00 g or 0.002 kg.
1. The heterozygous F1 individuals undergo independent assortment to produce variation among the genotype of F2 population. Hence in genetic variation (VG) is also involved along with environmental variation to obtain phenotypic variance of F2 population (Vp).
Vp = VG + VE
VG = Vp - VE
VG = 5.90