10 Would you expect good nutrition to increase or decrease the heritability of

10 would you expect good nutrition to increase or

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variation about a low mean, whereas well-fed people have genetic variation about a high mean. 10. Would you expect good nutrition to increase or decrease the heritability of height? (hint, how does this affect V E ). Good nutrition should increase the heritability of height by elimination some of the environmental variance. It affects only the denominator in a heritability equation. 11. Two adult plants of a particular species have extreme phenotypes for height (0.4m tall and 2m tall), a quantitative trait. a) If you only had one uniformly lighted greenhouse, how would you determine whether the variation in plant height is environmentally or genetically determined? Grow the plants under uniform environmental conditions to see the environmental role in height. b) How would you attempt to estimate the number of allelic pairs that may be involved in controlling this trait? By crossing the plants and looking at the extremes of the F2 generation, it is possible to estimate the number of genes involved in this trait. 12 a).If skin color is caused by additive genes, can marriages between individuals with intermediate- colored skin produce: i) light-skinned offspring, ii) dark-skinned offspring? Yes, two Aa Bb Cc Dd individuals can produce AA BB CC DD or aa bb cc dd and other variations with more or less than 4 contributing alleles. b) Can marriages between light skinned individuals (zero contributing alleles) produce dark-skinned offspring. No, two aa bb cc dd individuals are homozygous and cannot produce darker colored individuals. 13. A plant with a genotype of aa bb and a height of 40 cm is crossed to a plant with a genotype of AA BB and a height of 60cm. If each dominant allele contributes to height additively, what is the expected height of the F1 progeny and the expected contribution of each contributing allele. Expected height of the F1 (Aa Bb) is 50 cm. The difference in height of the two plants is 20cm and the tall plant has 4 contributing alleles, so each contributing allele contributes 5 cm. 14. Two strains of wheat were compared for the time required to mature. Strain X required 14 days and Strain Y required 28 days. The strains were crossed, and the F1 generation was selfed. One hundred F2 progeny out of 6,200,000 matured in 14 days or less. How many genes may be involved in maturation? The frequency of individuals in the F2 that resemble one parent is (1/4) n , where n= the number of genes involved. In this case, 100/6,200,000 is approximately (1/4) 8 . So there are probably 8 genes involved.
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  • Spring '11
  • dr
  • Genetics, 2m, VE, heterozygote, 20g

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