1. Phenotypic diversity

Question 1

Define DNA

Answer 1

double-stranded, helical nucleic acid molecule that is the carrier of genetic information and the fundamental substance of which genes are composed

Question 2

Chromosome

Answer 2

a strand of DNA that is encoded with genes and made up of DNA tightly coiled many times around proteins called histones (for support)

Question 3

Gene

Answer 3

Basic physical unit of heredity and the DNA sequence at specific location on a chromosome

Question 4

allele

Answer 4

Alternative form of genes
>2 possible alleles at a locus
only two possible alleles one from sire and one from dam

Question 5

Locus

Answer 5

a particular position or place where a piece of DNA is situated

Question 6

Homozygote

Answer 6

individual carrying two alike alleles

Question 7

Heterozygote

Answer 7

individual carrying two unlike alleles of a gene

Question 8

Genotype

Answer 8

Genetic constitution of an individual

combination of alleles at a particular locus

Question 9

Chromatid

Answer 9

each of the two thread-like strands into which a chromosome divides longitudinally during cell division
each contains a double helix of dna

Question 10

Karyotype

Answer 10

the chromosome complement of an individual defined by the number, form and size of the chromosomes

Question 11

how many chromosomes do cattle have (2n)

Answer 11

60

Question 12

how many chromosomes do pigs have (2n)

Answer 12

38

Question 13

Mendel’s first law

Answer 13

law of segregation
during gamete formation each member of the allelic pair separates from the other to form the genetic constitution
gamete only have half the number of chromosomes
thus each parent contributes only one allele to the offspring

Question 14

Medel’s second law

Answer 14

law of independent assortment
genes assort independently during meiosis if all possible gametes are formed in equal proportions
pairs of alleles are passed on to offspring independently
offspring can possess combinations of genes that none of the parents had

Question 15

Exceptions to Mendel’s law

Answer 15

Linkage
independent segregation depends on the genes being unlinked
loci are linked when located on the same chromosome

Question 16

explain mendelian sampling

Answer 16

random samples of parental genes caused by segregation and independent assortment

Question 17

give three external environmental factors

Answer 17

nutrition
parasites
climate

Question 18

give three internal environmental factors

Answer 18

age of dam
birth status
gender

Question 19

why bother with breeding and selection

Answer 19

in a given environment animals with superior genetics will always outperform animals with inferior genetics
so we can get better results with animals with good genetics if the selection and genetics complement the environment

Question 20

Define selection

Answer 20

choosing and growing specific individual animals with desirable characteristics to breed with them and improve genetics of new generations

Question 21

Define animal breeding

Answer 21

the directed development of breeds through the selection of parent animals expressing desired traits

Question 22

list three types of selection and explain what is achieved through each

Answer 22

Directional-to move the mean of the population either higher or lower so that weaker genetics is eliminated

Stabilizing- to have a more centralized mean with less genetic variation away from the mean

Disruptive-eliminating the middle of a bell curve to disrupt the mean and move the variation further away from the mode

Question 23

define traits

Answer 23

traits are observable/ measurable characteristics eg birthweight

Question 24

define a Phenotype

Answer 24

the measured level of performance for a traits eg. 35 kgs.

Question 25

list 4 fitness traits

Answer 25

litter size
ovulation rate
calving interval
survivability (fertility and reproduction)

Question 26

list 4 production traits

Answer 26

weight
growth rate
milk yield
greasy fleece yield

Question 27

list 2 quality traits

Answer 27

meat tenderness

butterfat

Question 28

list 3 type traits

Answer 28

udder conformation
legs
functional efficiency

Question 29

list 2 behavioral traits

Answer 29

temperament

learning ability

Question 30

give the Hardy-Weinberg law

Answer 30

in a randomly mating population in which there is
no selection, mutation, migration, or genetic drift

genotypic freq. in offspring are determined solely by allele freq. in parents
and allele frequencies and genotype freq. remain constant from generation to the next

Question 31

Explain random mating

Answer 31

choice of partner independent from genotype and phenotype

Question 32

Explain genetic drift

Answer 32

genetic drift is the natural fluctuation in the frequency of genes