ANSC 305 Riley Exam 2

A ram suspected of being a carrier at a major locus with dominant gene action has P0 = 0.33. This likely means that:

his parents were carriers at this locus

P(DN) = LOC = 0.75. This means (with respect to a locus with 2 alleles and complete dominance genetic action)

Known heterozygotes would be identified with probablity = 0.75

Lethal recessive alleles sometimes affect population allele and genotype frequencies--all the following are true except.

(a) early embryonic deaths are not observed, so homozygous recessive individuals never appear

(b) homozygous recessive individuals are sometimes born, but do not live long.

(c) early embryonic deaths cut into the heterozygote frequencies in the populations.

(d) Homozygous recessive individuals are sometimes born, but are not able to live normally and contribute to the population

c

With respect to a locus with 2 alleles and complete dominance genetic action for some character, one heterozygous parent and one homozygous recessive parent should produce on average:

1/2 phenotypically dominant and 1/2 phenotypically recessive

A is the dam of B no other paths of relatedness between them. Fa = 0.0625; Rab = ?

(1/2) (1.0625) = 0.53125

Why are harmful recessive alleles not removed from the population by natural selection?

they are present in heterozygotes

Production system complementarity definition:

specialized sire lines or breedtypes and specialized dam lines or breedtypes are used to enhance system productivity

Fiber producing goat(s)?

(a) angora, boer

(b) angora, dorper

(c) angora, dorper, boer

(d) angora

d

In the context of a single locus with complete dominance and 2 alleles B and b, and individuals with genotype bb die shortly after birth, it would be expected that:

f(b) should be low in the population that lives

Hampshire:

(a) terminal type swine breed

(b) US origin

(c) "Up" ears

(d) all are correct

(e) black with a white belt

d

P(HD I CT) with respect to a single locus with 2 alleles (A and a) and dominance as the genetic action--all of the following are correct except:

(a) combines information about probability of being homozygous dominant at this locus based upon initial information and a successful progeny test (no homozygous recessive progeny produced)

(b) lets us know with certainty that an individual is AA

(c) parameter space of 0 to 1.

(d) is sequential; that is, more information supporting the probability of being homozygous at this locus can be added across time

(e) could help with making selection or mating decisions with respect to this locus

b

In the context of a single locus with complete dominance and 2 alleles B and b, a phenotypically dominant individual is suspected of being a heterozygote at this locus. Po = 1/3; LOC = 3/4; P(HD I CT) = ?

2/3...

In cattle, base coat color is due to a single locus (allegedly; for this problem assume it is due to a single locus with complete dominance of black over red base color). An Angus herd has only these alleles: E and e. A black heifer from that herd suspected of having genotype Ee at this locus has father with genotype Ee and red mother. This heifer:

has genotype Ee

In the context of a single locus with complete dominance and 2 alleles C and c, a phenotypically dominant individual is suspected of being a heterozygote at this locus. Po = 0.2; LOC = 0.6; P(HD I CT) =?

0.385...

Additive relatedness between full-siblings range:

0 to 1

All of the following are true about inbreeding execpt:

(a) illegal in all 50 US States as well as territories

(b) increases levels of homozygosity in an individual

(c) sometimes results in reduced fitness of individuals

(d) Fx = 1/2 ax's parents

(e) parameter space of Fx 0 to 1

a

Statistical measures of association of two variables used often in genetics and animal breeding : regression coefficient and correlation coefficient, all are true except:

(a) share the same numerator

(b) have different parameter spaces

(c) share the same denominator

(d) can be expressed as mathematical functions of each other

(e) indications of correspondence of values of one character with values of another character

a

Spider lamb syndrome:

(a) recessive lethal

(b) causes malformed and twisted legs

(c) genetic test available

(d) traced back to the Suffolk ram Walking Tall

(e) all of these statements are correct

e

Consider a single locus in cattle with 2 alleles (D, d) and complete dominance; the homozygous recessive genotype (dd) is responsible for dwarfism. A non-dwarf bull sires a dward calf.

(a) His genotype is known with certainty: Dd

(b) His genotype is known with certainty: DD

(c) His genotype with probability = 0.9 is Dd

(d) His genotype with probability = 1/3 is DD

(e) His genotype with probability = 1/3 is Dd

a