exam 3

Question 1

What is the genetic and phenotypic effect of inbreeding?

Answer 1

Causes an increase in homozygosity and a decrease in genetic variation.

Question 2

Jacob

Answer 2

wool

Question 3

Merino

Answer 3

wool

Question 4

suffolk

Answer 4

meat

Question 5

angora

Answer 5

hair

Question 6

Boer

Answer 6

meat

Question 7

nubian

Answer 7

dairy

Question 8

when making selection decisions, what is a management challenge?

Answer 8

Increasing intensity also means testing more animals, increasing cost

Question 9

when making selection decisions, the manager may not control…

Answer 9

heritability of the animal

Question 10

which of the statements is FALSE about multiple trait selection?

Answer 10

traits of economic value should not be considered

Question 11

the probability of multiple independent events is the…

Answer 11

product of the probabilities of each event

Question 12

what is the disadvantage of tandem selection for traits?

Answer 12

it takes 2 generations before the effect of the 2-trait selection is observed

Question 13

which of the following is TRUE?

Answer 13

the rate of inbreeding is faster in plants than animals

Question 14

_____ alleles are usually favorable over ______ alleles, so culling the less desirable animals results in an increase in the frequency of the dominant or favorable allele.

Answer 14

dominant; recessive

Question 15

inbreeding does what to the traits related to physical fitness in animals?

Answer 15

decreases them

Question 16

inbreeding should be used…

Answer 16

for the development of seed stock animals

Question 17

when selecting breeding animals, which of the following should be used?

Answer 17

animals superior for desirable traits

Question 18

linebreeding, a form of inbreeding, is used for what?

Answer 18

to increase the relationship animal of one ancestor

Question 19

A manager introducing a new trait or allele into a herd is an example of…

Answer 19

Migration

Question 20

In purebred herds, producers may create a small amount of hybrid vigor by…

Answer 20

Outbreeeding/outcrossing

Question 21

Which is true about heterosis?

Answer 21

Heterosis is not accurately estimated by a single mating because of environmental factors

Question 22

What is not a practical use of hybrid vigor?

Answer 22

Breeding two animals that have the worst performance in their herds

Question 23

difference between mean of selected parents and the population from which they came

Answer 23

selection differential

Question 24

expression of the probability that two individuals possess identical genes

Answer 24

coefficient of relationship

Question 25

alternating selection among traits across generations

Answer 25

tandem selection

Question 26

culling based on a minimum level of performance for each trait

Answer 26

independent culling levels

Question 27

selection of animals with high performance in any on trait

Answer 27

selection for extremes

Question 28

the time it takes for any genetic improvement made in the selection program of the top tier of the pyramid to trickle down to commercial level

Answer 28

genetic lag

Question 29

negative effect of inbreeding on vigor when management controls for environmental effects

Answer 29

inbreeding depression

Question 30

the mating of animals that are related

Answer 30

inbreeding

Question 31

the mating of animals that are related in order to propagate the genes of one particular animal

Answer 31

linebreeding

Question 32

the mating of animals of two or more different breeds

Answer 32

crossbreeding

Question 33

the mating of unrelated animals within a breed. although crossbreeding is more extreme than outcrossing, the genetic effects are similar

Answer 33

outcrossing

Question 34

increased performance of the offspring over the average performance of the parents when unrelated individuals are mated

Answer 34

heterosis

Question 35

purebred animals of two different breed are used for crossing to create an F1

Answer 35

two-breed cross

Question 36

crossbred F1 females are kept for breeding and are mated to nonrelated males from one of the parent breeds

Answer 36

two-breed rotation

Question 37

males from each of the three breeds are used in succession on crossbred females

Answer 37

three-breed rotation

Question 38

f1 females are produced from two purebred line, then bred to a different breed of sire to produce market offspring

Answer 38

three-breed terminal cross

Question 39

as selection intensity increases, response to selection ________

Answer 39

increases

Question 40

predicting individual offspring is typical for ________ but is not used for __________ because group performance is more important

Answer 40

companion animals; commercial animals

Question 41

when selecting for multiple traits, the value of selection (response to selection) for each individual trait will ______ for each trait, compared to the effect of selecting for a single trait

Answer 41

decrease

Question 42

many breeds were developed as a function of

Answer 42

inbreeding

Question 43

traits with high heritability have ________ heterosis than traits with low heritability

Answer 43

less

Question 44

outcrossing and crossbreeding ____________ heterozygosity

Answer 44

increase

Question 45

heterozygosity __________ after the F1 generation

Answer 45

decreases

Question 46

reciprocal crosses must be evaluated for performance because of __________ influences

Answer 46

maternal

Question 47

as animals mature, heterosis has ________ of an effect because of environmental influences

Answer 47

less

Question 48

two breed rotations eventually stabilize at ____ Breed A and ______ breed b or the inverse

Answer 48

2/3; 1/3

Question 49

three-breed rotations eventually stabilize at proportions of ____, _____, and _______

Answer 49

4/7 A; 2/7 B; 1/7 C