A three-gene system of additive genes (A, B, and C) controls plant height. Each gene has two alleles (A and a, B and b, and C and c). There is dominance among the alleles of each gene, with alleles A, B, and C dominant over a, b, and c. Under this scheme, the dominant genotype for a gene contributes 10 cm to height potential, and the recessive genotype contributes 4 cm. What are the phenotypes and proportions of each phenotype among the F₂?
Table of contents
- 1. Introduction to Genetics51m
- 2. Mendel's Laws of Inheritance3h 37m
- 3. Extensions to Mendelian Inheritance2h 41m
- 4. Genetic Mapping and Linkage2h 28m
- 5. Genetics of Bacteria and Viruses1h 21m
- 6. Chromosomal Variation1h 48m
- 7. DNA and Chromosome Structure56m
- 8. DNA Replication1h 10m
- 9. Mitosis and Meiosis1h 34m
- 10. Transcription1h 0m
- 11. Translation58m
- 12. Gene Regulation in Prokaryotes1h 19m
- 13. Gene Regulation in Eukaryotes44m
- 14. Genetic Control of Development44m
- 15. Genomes and Genomics1h 50m
- 16. Transposable Elements47m
- 17. Mutation, Repair, and Recombination1h 6m
- 18. Molecular Genetic Tools19m
- 19. Cancer Genetics29m
- 20. Quantitative Genetics1h 26m
- 21. Population Genetics50m
- 22. Evolutionary Genetics29m
20. Quantitative Genetics
Analyzing Trait Variance
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
If you wanted to identify what proportion of trait variation is due to genetics, you would do what?
A
Control for environmental variation
B
Control for overall variation
C
Control for genetic variation
D
Control of phenotypic variation

1
Understand the concept of heritability, which is the proportion of phenotypic variation in a population that is attributable to genetic variation among individuals.
Recognize that phenotypic variation is the observable variation in traits among individuals in a population, which can be influenced by both genetic and environmental factors.
To determine the proportion of trait variation due to genetics, you need to control for environmental variation. This means ensuring that environmental factors are consistent or accounted for, so that any remaining variation can be attributed to genetic differences.
Consider using methods such as twin studies, adoption studies, or controlled breeding experiments, which help isolate genetic factors by minimizing environmental differences.
Finally, calculate the heritability estimate, which is the ratio of genetic variance to total phenotypic variance, often expressed as a percentage or a value between 0 and 1.
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