MBG2400 Exam Questions with Complete Correct Answers | Grade A+

Qualitative traits Ans: controlled by one or a few loci; discrete phenotypes (eye colour, coat colour, seed colour, seed texture, blood type, colourblindness etc) Quantitative traits Ans: controlled by multiple loci (also called polygenic traits); continuous phenotypes (height, weight, racing speed, milk yield, temperature, intelligence, temperament, schizophrenia - threshold trait) -- the range is measured as variation -- many loci contributing to the phenotype P = G + E Ans: phenotype = genotype + environment genotype = many loci contributing 2 environment = conditions in which the genotype is expressed Categorical traits Ans: discrete phenotypes; categories are laid over a continuous variable and each has a threshold e.g. calving ease - unassisted/easy pull/hard pull/surgical or mal-presentation Threshold Traits Ans: polygenic traits that are inherited quantitatively due to the contributions of many genes and categorized by a small number of discrete phenotypes Variance Ans: Measure of how much variability there is within a population for a certain trait (unable to calculate from threshold traits) Heritability (h^2) Ans: proportion of total variance that is additive genetic and half is transmitted from parent to offspring 3 Loci Ans: specific location/site in the genome, most have a small effect but occasionally have a larger effect QTL Detection Ans: Goal is to find a polymorphism in the genome that is associated with a distinct difference in phenotype QTL Genotyping Ans: Individual locus genotyping, usually an 'unimportant' polymorphism and normally don't genotype the QTL itsel