3_fundamentals of animal breeding and genetics tutorials

ABG 300 (Fundam entals of Animal Breeding & G enetics)

Tutorial questions

WEEK 1

1. Describe ho w cattle and poultry were domesticated giving the tim e, place reasons for (what led to)
domest ic at ion.
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2. Give a brief account of ho wthree species of farm animal wer e dom esticated
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3.In few concise statem ents, state the contribution of the follo win g peop le to the developm ent of
Animal Breedin g and Genetics. (i) Ro bert Bakewell (ii) Gr egory Mendel (iii) Rolan d Fisher and
Sewell Wright (iv) W illiam Bateson (v) An gust Weishmann (v i) Ian Wilmut. (Bonus will be giv en for
correct dates)
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WEEK 2

4. What is the im plication of each of the following on Men delian ratio? ( i) Co dom inance (ii)
Epistasis (iii) Incomplete dominance (iv) Dominan ce ( Give goo d illustrations in each case)

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5. State the two Men delian laws. With specific examples, explain what the lawm ean s
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WEEK 3

6. Define monohybrid an d dihybrid inheritance
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7. State the law of in dependent assortment and indicate all possible gametes that could be produced by
an animal with genotype AaBb.
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8. An animal heterozygo us for two indepen dently assorting pairs of genes (AaBb) is self fertilized. (i)
With the aid of a punnet squar e, draw the inh eritance of the interse mating (AaBb x AaBb) at F2. (ii)
Determ ine the expected fr equency of the following genotypes in the pro geny of such an anim al:
AABB, AaBb, aaBB.

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WEEK 4
9. State four facts that could explain the mechanism of inheritance.

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10.Differ entiate between these pairs giving goo d ex am ples. (i) Quantitative and Qualitative inher itance
(ii) Co dom inace and No dom inan ce (iii) Dilutin g an d Inhibitory epistasis.

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11.Coat colour s in cats ar e caused by the interactions of sever al genes, some affecting the ability to
produce the black pigment eumelan in, some the red pigment phaeomelan in an d some the patterns of
deposition of pigm ent. A bro wn tabby cat is crossed to a solid cinnam on cat. All the kittens resultin g
from this cross are bro wn tabbies. W hen adult these F1 were allowed to inter-cross freely with each
other to produce an F2. In the resulting explo din g cat population fo ur classes of cat could be seen,
bro wn tabbies, cinnamon tabbies, solid black s and solid cinnam ons in the relative proportions 9:3 :3:1.
Account for these observ ations.

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12.The Manx cat follo ws Mendelian Ratio. True or false? Discuss

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1. With annotated diagr am s only, distin guish between: (i) The major morphological classes of
chrom osomes. (ii) the behav iour of chromosom es dur ing metaphase of m itosis, meiosis I an d m eiosis
II (iii) What is the significance of m eiosis to liv ing organism

2. Define a karyotype an d state 2 main featur es of a karyotype.

3. Write short notes on the follo win g (i) Str ucture of chromosome. ( ii) Classification of chromosom es
based on the position of the centrom ere. (iii) Sex determination in Farm anim als.

4. What is mitosis?

5. Assuming an or gan ism has a hap loid set of 2 chromosom es, sho w clearly
the behav iour of chromosom es durin g m itosis usin g annotated diagram s only.

6. Distinguish bet ween m itosis an d m eio sis at prophase of cell division.

7. Ho w is sex determ ined in anim als?

8. Briefly discuss the sign ificance of the following to livin g or gan isms. ( i) Mitosis (ii) Meiosis.

9. Meiotic recombination is part of both haploid an d dip loid life cy cles. Discuss

10. The number of chrom osomes (2n) in the cell of a rabbit is 44. how many chromosom es are present
in: (i) Prim ary sp erm atocyte (ii) Spermatozoa (iii) Ova (iv) Polar bodies?

11. A fem ale anim al with genotype AaBb is crossed with double r ecessive male (aabb)

12. State the lawof product pro bability.

13. State one similarity an d differ ence between dom inance an d epistasis.

14. State and briefly exp lain with an exam ple the condition under which there co uld be a depart ure
from the F2 Mendelian ratio.

15. Short hair in rabbits is governed by a dom inant gene (L) and a long hair by a recessive allele (l).
Black hair results from the action of dom inant genotype ( B-) an d brown from recessive genotype (bb)
(i) What genotypic and phenotypic ratios ar e expected am ong the pro geny of cro sses between
homozygo us short-black and dihybrid short-black r abbits?
(ii) What type of epistasis is in operation if mating bet ween black rats of identical genotype produced
cream -colored, black an d albino offspr in g in the ratio 9:3:4 ?

16. Ho w is epistasis diff erent from dom inance?

17. In short horn cattle, the hom ozygous genotype RR pro duces red, rr pro duces wh ite an d Rr produce
roan (mixture of red an d white). The presence of horns is pro duced by the homozygous recessive

genotype pp and the polled condition by its dom inant allele P. if roan co ws heterozy go us for the horn
gen e are m ated to roan-horned bulls, what are the expected ph enotypic ratios in the offspring?

1. Write short notes on the follo win g phenom ena. (i) Penetrance an d expressivity (ii) Pleitropy and
Linkage ( iii) Coup lin g an d r epulsion (iv) Interchrom osomal an d intrachromosom al recom bin ation
2. Discuss the term penetrance an d expressivity.
3. Write an essay on pleitropy
4. What is recombination
5. Define (i) Linkage ( ii) Recom bin ation.
6. A female anim al with genotype AaBb is crossed with a double-r ecessive m ale (aabb). Their progeny
include 442 AaBb, 458 aabb, 46 Aabb an d 54 aaBb. Explain these results.
7. When true-breedin g brown goats are mated with certain true- breedin g wh ite goats, all the F1 kids
are white. The F2 from som e F1 X F1 cro sses were 118 white, 32 black an d 10 bro wn kids. W hat is
the genetic basis for these results?

PRAC TICALS
1. List the characteristics features of Niger-hyb pig. Describe the other breeds in UNAAB Farm
2. Give t wo distinguishing feat ures each between (a) n am ed breeds of goats an d (b) named br eeds of

sheep
3. Differentiate between a breed an d strain. List 7 different strains fo und in poultry unit an d their
distin guishin g features
4. Explain (i) Species (ii) Breed (iii) Strain.
5. List the different sp ecies of livestock available in COLANIM Farm
6. List at least two br eeds available in fo ur of them
7. Describe one breed from each of the four breeds