Animal Genetics

Question 1

Process of Natural selection

Answer 1

Member of a species have variations that are inherited, species overbreed or produce more offspring than necessary, members of the species must compete for limited resources (food, mates),
Members of the species that are best adapted will survive and reproduce.
The traits of the survivors will accumulate in the population and the traits of the weaker (poorly adapted) species will become rarer.

Question 2

Genetic Engineering

Answer 2

The artificial manipulation of genes between organisms of different species such that it can carry out tasks not usually associated with the organism.

Question 3

Advantages of genetic engineering

Answer 3

Improved milk yield (cows)
Improved milk quality
Improved carcass quality
increased prolificacy
faster growth rates
increased disease resistance

Question 4

Why is progeny testing of dairy bulls more reliable than performance testing

Answer 4

Bulls produce many offspring, the average results of many are more accurate indicators than the results of just one animal, bulls cannot be performance tested for milk production,
but can be progeny tested for milk production,
the female offspring of the bull can be tested

Question 5

genotype

Answer 5

The genes that make up the trait which is expressed in an individual

Question 6

genotyping

Answer 6

Comparing the genetic sequences of an organism to that of another

Question 7

Genomic selection

Answer 7

Animals or plants selected based on their DNA examined and compared to reference data

Question 8

Advantages of genomically selected animals

Answer 8

Increased animal performance (milk yield/quality/LWG)
Early identification of genetically superior animals for breeding
Identify prolific sires to have increased offspring

Question 9

Genetic improvements based on physical traits

Answer 9

Farmer identifies trait (double muscle,udder,sound feet, polled)
- Then farmer selectively breeds from these superior animals to achieve superior offspring
- This results in higher profit

Question 10

A way to reduce need for antibiotic use on farms

Answer 10

Better hygiene to prevent animals from picking up disease
- Screen herd for different diseases and only provide antibiotics if disease is present
- cull persistently infected animals so they don’t pass on infections to other animals
-use of vaccinations to prevent disease

Question 11

significance of meiosis in gamete formation

Answer 11

Halves diploid number, allows for fertilisation and promotes variation

Question 12

“Crossing over” process and signifigance

Answer 12

Process : Homologous chromosomes , exchange DNA
Significance : Allows variation

Question 13

Performance testing

Answer 13

Comparing records of an animals performance with the records of similar animals kept under the same conditions to identify superior animals

Question 14

Back cross

Answer 14

Breeding a crossbreed offspring with a pure breeding recessive, both expressed in phenotype, resulting in an intermediate trait

Question 15

Clone

Answer 15

A group of cells that are genetically identical to each other

Question 16

Tetraploid

Answer 16

More than two copies of the each chromosome

Question 17

2 reasons male animals are castrated on farms

Answer 17

Agressive, danger to farmer, meat not as marketable and interfere with breeding program

Question 18

Pedigree herd

Answer 18

All animals descended from a pure breeding line

Question 19

recessive allele

Answer 19

Not expressed when paired with a dominant allele, only when paired with another recessive allele

Question 20

Natural Service

Answer 20

Use of a male in the herd to fertilise the females

Question 21

Independent assortment

Answer 21

When either pair of alleles can combine with either of another pair

Question 22

Incomplete dominance

Answer 22

neither the dominant nor the recessive gene is able to be expressed so a compromise is achieved. Blend of the two alleles in the phenotype

Question 23

Sex linkage

Answer 23

A gene found on the X chromosome but no copy on the Y chromosome, located only on sex determining chromosomes

Question 24

Mopping up

Answer 24

Involves a stock bull detecting and servicing any cows or heifers not in calf

Question 25

Sexed semen in a dairy herd

Answer 25

90% chance of producing a female calf , which are raeared as replacements in the dairy herd, allows for expansion of dairy herd while maintaining biodiversity
OR
Sexed semen can be used on genetically superior cows to produce bulls for breeding

Question 26

Distinguish between selectively breeding and interbreeding

Answer 26

Selectively breeding = process of breeding animals or plants with desirable traits and concentrating on those desirable traits in their offspring.

Interbreeding = Is the mating closely related animals which increase the chances of offspring being affected by undesirable recessive traits.

Question 27

Mendels 2 Laws

Answer 27

Indépendant Assortment = Either member of a pair of allies can combine with either member of another pair of alleles on different chromosomes at gamete formation

Law of Segregation = pair of alleles controlling a trait separate at gamete formation

Question 28

Polyploidy

Answer 28

Cells with more than 2 sets of chromosomes eg wheat or endosperm

Question 29

Freemartin condition

Answer 29

Infertility in female animals that have a male twin

Question 30

Micropropagation

Answer 30

Plant tissue grown to produce clones identical to the parent eg seed potato propagation.

Question 31

Embryo transfer

Answer 31

Embryos from one (donor) animal implanted into a surrogate

Question 32

Benefits of embryo transfer

Answer 32

More offspring from superior stock
-genetic improvement
-produces replacement stock
-decreases time for genetic improvement

Question 33

Progeny testing

Answer 33

Keeping a record of the performance of an animals offspring with the offspring of other animals kept under the same conditions to identify superior breeding stock

Question 34

Continuos variation

Answer 34

Characteristics controlled by a number of genes

Question 35

Hybrid vigour

Answer 35

The increased productivity displayed by offspring from genetically different parents