In need of assistance. Please help answer the following. 1) Pure-breeding yellow

Question

In need of assistance. Please help answer the following.

1) Pure-breeding yellow guinea pigs crossed with pure-breeding white guinea pigs produce only cream-colored offspring. This pattern indicates incomplete dominance. Rough hair is found to be dominant to smooth hair. Give the F1 and F2 genotypic and phenotypic ratios of a cross of a smooth white guinea pig with a homozygous rough yellow guinea pig.

2) A breeder of cattle has a herd of white cows and a roan bull. Hair color in this breed is controlled by an incomplete dominant gene. The two homozygous forms are either red or white, and the heterozygous is roan. Answer the following questions please

What color calves are expected and in what proportion?

Outline a procedure to develop an all-red herd.

3) In horses, black coat color is influenced by the dominant allele (B), and chestnut coat color is influenced by the recessive allele (b). Trotting gait is due to a dominant gene (T), pacing gait to the recessive allele (t). If a homozygous black trotter is crossed with a chestnut pacer:

What will be the appearance of the F1 and F2 generations?

Which phenotype will be the most common?

Which genotype will be the most common?

Which of the potential offspring will be certain to breed true?

4) In garden peas, one pair of alleles controls the height of the plant and a second pair of alleles controls flower color. The allele for tall (D) is dominant to the allele for dwarf (d), and the allele for purple (P) is dominant for the allele for white (p). A tall purple crossed with a tall purple produces ¾ tall purple and ¼ tall white. What is the genotype of the parents ?

5) Three alleles control the ABO blood types. IA and IB are codominant genes, so the combination of IAIB produces the AB blood type. The third allele Iois recessive to the other two alleles. Indicate which of these parents could produce the given child and submit your response to the instructor.

A X AB produce B child.

A X O produce A child.

A X B produce O child.

A X AB produce O child.

A X AB produce B child.

B X B produce O child.

AB X AB produce A child.

Explanation / Answer

1. this means that the parents are rryy and RRYY (R-rough, r-smooth, Y-yellow, y-white skin)
the F1 population would all be rough hair and cream coloured skin - phenotype while the genotype would be RrYy. since Rr is dominant therefore rough and since Yy is codominant therefore cream coloured skin

now if u self them u get 4 different types of gametes: RY, Ry, rY, ry
now putting them in a mendalian double hybrid cross u get the genotypes
RRYY-1- rough hair yellow skin
RRYy- 2 - rough hair cream skin
RrYY-2 - rough hair yellow skin
RrYy-4 - rough hair cream skin
RRyy-1 - rough hair white skin
Rryy-2 - rough hair white skin
rrYY-1 - smooth hair yellow skin
rrYy-2 - smooth hair cream skin
rryy-1 - smooth hair and white skin

there fore your phenotypic ratios would be
rough hair and yellow skin - 3
rough hair and cream skin - 6
rough hair and white skin - 3
smooth hair and yellow skin - 1
smooth hair and cream skin - 2
smooth hair and white skin - 1

2.

Incomplete dominant gene.
R1: red
R2: white

Genotype Phenotype
R1R1 --> red
R2R2 --> white
R1R2 --> roan

2. P: white (R2R2) x roan (R1R2)
(a) F1: 1R1R2 (roan) : 1 R2R2 (white)

(b) you can develop an all-red herd by breeding a red cow and a red bull.

3.

Set up a Punnett Square with the two horses' genotypes. Homozygous means two of the same allele (e.x. tt or BB) and heterozygous means the horse has one dominant and one recessive allele for a trait, such as Bb). The first horse is a homozygous black trotter so it's genotype is BB, and it's gaits so it's TT, since T is a dominant allele and the horse is homozygous. The other horse is bb tt because it's chestnut, which means it has the recessive alleles for color and it paces, which means it has two recessive alleles. Now, with that info, set up two Punnet Sqaures with the two horses' genotypes.

B B

b Bb Bb

b Bb Bb

T T

t Tt Tt

t Tt Tt

Any time an organism that is homozygous recessive and an organism that is homozygous dominant are breeded, the offspring will always have heterozygous genotypes, but will always show whatever the dominant trait is.

4.

For the first cross, we have

D?pp crossed with ddP?, where ? represents unknown genotype.

We see that half the offsprings are tall and half are dwarf, which meant that the parent must be heterozygous, i.e. Ddpp or else no dwarf plant will result.

Likewise, half the offspring have white flowers and the other half white, so the gene for colour must also be heterozygous, i.e. ddPp

Overall we have a cross of
tall white Ddpp with
dwarf purple ddPp

Question 2:
Both parents are tall, but the recessive dwarf phenotype is shown in the offspring. This means both parents must be heterozygous for the height gene, i.e. Dd.

For colour, we have P? crossed with pp, and both colour types are seen. so the purple plant must be heterozygous.

Therefore parental genotypes are:
tall purple DdPP
tall white DdPp

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