ANSC 4395-Breeding & Genetics FINAL|
QUESTIONS WITH COMPLETE ANSWERS
Simply-Inherited Traits: Correct Answer: Traits affected by only a few genes
EX: Coat color, Horns
Simply-inherited Traits:
-Qualitative or categorical Correct Answer: Either/or expression
EX: Black or red, Horned or polled
Simply-inherited Traits are rarely... Correct Answer: quantitative (Measured with numbers or
continuous)
EX: White spotting in cats (1-9 numerical rating)
Simply-inherited Traits are typically, affected very little by... Correct Answer: environment
EX: Chocolate lab may bleach out if left in the sun, but there is no mistaking it for a black or
yellow lab
Polygenic Traits: Correct Answer: Affected by many genes with no gene having an overriding
influence
EX: Growth rate, Milk production, Ribeye area
Polygenic Traits are typically... Correct Answer: quantitative or continuous in expression
-Phenotypes are usually described by numbers
EX: Weaning weights, Milk yield, Ribeye Area
Polygenic Traits are greatly influenced by... Correct Answer: environment
-Lack of feed
-Heat/cold stress
-Training of quarter horses (speed)
Some polygenic traits have categorical phenotypes, called what? Correct Answer: Threshold
Traits
-Pregnancy (pregnant or not pregnant)
-Dystocia (1-5)
-Natural gait (trotter or pacer)
-Influenced by many genes but have an either/or result
, Between simply-inherited and polygenic traits, which is more important? Correct Answer:
Typically, polygenic traits
-Growth rate, fertility, milk production
-Traits that determine productivity and profitability
Traits: Some markets are more sensitive to... Correct Answer: simply-inherited traits
-Coat or feather color
-Polled
Genetic defects are usually... Correct Answer: simply-inherited
Common Characteristics of Simply-inherited & Polygenic Traits: Correct Answer: -Both are
subject to the same Mendelian mechanisms (Laws of segregation & independent assortment)
-Dominance and epistasis affect both
-Principles of selection and mating apply to both (attempt to increase the frequencies of
favorable alleles)
Different Breeding Approaches-
Function of the number of genes involved: Correct Answer: -The more genes involved, the more
difficult it is to observe the effects of individual genes, and therefore the less specific info we
have about those genes
-More "noise" in equation
-When a few or one gene affects a trait, the effects of those genes are well understood (EX:
Color, Polled)
What are test matings? Correct Answer: Matings designed to reveal the genotype of an
individual for a small number of loci
-Simply-inherited traits
Test Matings-
Polygenic traits: Correct Answer: Polygenic traits have so many genes affecting them that this is
impossible
-Can not observe the effects of specific genes
-Have to characterize the net effect
-EX: Breeding Values, EPDs
There are 3 general types of test matings to determine if an individual is heterozygous: Correct
Answer: -Mating to recessives
-Mating to heterozygotes
-Mating a sire to his daughters
The method with the highest probability of detection is... Correct Answer: mating to recessives
-Probability of siring a recessive offspring is 1/2
Test Matings-
If the condition is deleterious, it may be hard to find... Correct Answer: homozygous recessives
QUESTIONS WITH COMPLETE ANSWERS
Simply-Inherited Traits: Correct Answer: Traits affected by only a few genes
EX: Coat color, Horns
Simply-inherited Traits:
-Qualitative or categorical Correct Answer: Either/or expression
EX: Black or red, Horned or polled
Simply-inherited Traits are rarely... Correct Answer: quantitative (Measured with numbers or
continuous)
EX: White spotting in cats (1-9 numerical rating)
Simply-inherited Traits are typically, affected very little by... Correct Answer: environment
EX: Chocolate lab may bleach out if left in the sun, but there is no mistaking it for a black or
yellow lab
Polygenic Traits: Correct Answer: Affected by many genes with no gene having an overriding
influence
EX: Growth rate, Milk production, Ribeye area
Polygenic Traits are typically... Correct Answer: quantitative or continuous in expression
-Phenotypes are usually described by numbers
EX: Weaning weights, Milk yield, Ribeye Area
Polygenic Traits are greatly influenced by... Correct Answer: environment
-Lack of feed
-Heat/cold stress
-Training of quarter horses (speed)
Some polygenic traits have categorical phenotypes, called what? Correct Answer: Threshold
Traits
-Pregnancy (pregnant or not pregnant)
-Dystocia (1-5)
-Natural gait (trotter or pacer)
-Influenced by many genes but have an either/or result
, Between simply-inherited and polygenic traits, which is more important? Correct Answer:
Typically, polygenic traits
-Growth rate, fertility, milk production
-Traits that determine productivity and profitability
Traits: Some markets are more sensitive to... Correct Answer: simply-inherited traits
-Coat or feather color
-Polled
Genetic defects are usually... Correct Answer: simply-inherited
Common Characteristics of Simply-inherited & Polygenic Traits: Correct Answer: -Both are
subject to the same Mendelian mechanisms (Laws of segregation & independent assortment)
-Dominance and epistasis affect both
-Principles of selection and mating apply to both (attempt to increase the frequencies of
favorable alleles)
Different Breeding Approaches-
Function of the number of genes involved: Correct Answer: -The more genes involved, the more
difficult it is to observe the effects of individual genes, and therefore the less specific info we
have about those genes
-More "noise" in equation
-When a few or one gene affects a trait, the effects of those genes are well understood (EX:
Color, Polled)
What are test matings? Correct Answer: Matings designed to reveal the genotype of an
individual for a small number of loci
-Simply-inherited traits
Test Matings-
Polygenic traits: Correct Answer: Polygenic traits have so many genes affecting them that this is
impossible
-Can not observe the effects of specific genes
-Have to characterize the net effect
-EX: Breeding Values, EPDs
There are 3 general types of test matings to determine if an individual is heterozygous: Correct
Answer: -Mating to recessives
-Mating to heterozygotes
-Mating a sire to his daughters
The method with the highest probability of detection is... Correct Answer: mating to recessives
-Probability of siring a recessive offspring is 1/2
Test Matings-
If the condition is deleterious, it may be hard to find... Correct Answer: homozygous recessives
