Test 2, Deck 7

Question 1

Yellow and white fruiting squashes are cross and give only yellow squashes (F1). If we let F1 fertilize, what will be the F2 phenotypic ratio?

Answer 1

yellow to white 3:1

Question 2

A cross between a rough-hair guinea pig and smooth hair guinea pig produces 8 rough hair and 6 smooth hair. Another cross between two smooth hair yields only smooth hair in all subsequent generation, which allele is dominant?

Answer 2

Rough hair

Question 3

A cross between a rough-hair guinea pig and smooth hair guinea pig produces 8 rough hair and 6 smooth hair. Another cross between two smooth hair yields only smooth hair in all subsequent generation, whats is the genotypes of the four parents ?

Answer 3

Parents 1: Rr rr

Parents 2 : rr and rr

Question 4

In fruit flies, the wild type v(wt) produces normal wings but the v(-) produces short wings. Two wild type wing flies cross and produce 88 normal and 35 short wings, What is the parent’s genotype?

Answer 4

V(wt)v(-) V(wt)v(-)

Question 5

In fruit flies, the wild type v(wt) produces normal wings but the v(-) produces short wings. If a F1 short-wing female crosses with her F0 father with normal wings, how many flies will be normal out of 80 of F2 ?

Answer 5

40 will ne normal

Question 6

A farmer orders 24 chicks, some have shorter legs. He crosses chicks with short and normal leg, he also crosses chicks with both short leg. He gets these offspring:
1st: Normal x Short –> 47 short, 43 normal
2nd: short x Short –> 39 short, 19 normal
Is the first cross useful to find which allele is dominant?

Answer 6

No, either could be dominant

Question 7

A farmer orders 24 chicks, some have shorter legs. He crosses chicks with short and normal leg, he also crosses chicks with both short leg. He gets these offspring:
1st: Normal x Short –> 47 short, 43 normal
2nd: short x Short –> 39 short, 19 normal
Is the second cross useful for finding the dominant allele? Is so, which one is it?

Answer 7

Yes, short is dominant

Question 8

A farmer orders 24 chicks, some have shorter legs. He crosses chicks with short and normal leg, he also crosses chicks with both short leg. He gets these offspring:
1st: Normal x Short –> 47 short, 43 normal
2nd: short x Short –> 39 short, 19 normal
What kind of inheritance pattern is it?

Answer 8

Lethal recessive (crossing two short legs gives two phenotypes which suggests that short leg are heterozygote. The proportion is 2:1, this suggests the homozygous recessive is lethal)

Question 9

When homozygous, a lethal recessive allele of bovines produces amputated calves. they die 2 weeks after birth. If two heterozygotes are crossed, which proportion of 1 year old offsprings should carry the allele?

Answer 9

2/3 will be heterozygous

Question 10

When homozygous, a lethal recessive allele of bovines produces amputated calves. they die 2 weeks after birth. How could a farmer that discovered that his cows gave birth to amputated calves get rid of this trait?

Answer 10

He would have to prevent all the cows that gave birth to amputated calves from reproducing in the futur.

Question 11

In a garden peas, tall vine is dominant to dwarf. Green is dominant to yellow. A tall, yellow plant is crossed with a dwarf green plant and produce 80 dawrf and green out of 320 offsprings. What is the genotype of parents?

Answer 11

Parents: Ttgg and ttGg

Question 12

In humans, homozygotes have either straight or curly hair, only heterozygote can have wavy hair. From mating two wavy hair individuals, what is the probability that 4 children in the family will have straight hair?

Answer 12

1/256

Question 13

When chickens with white feathers are crossed to black feathers, their offsprings are grey. When grey individuals are crossed, they produce white grey and black chickens. What is the inheritance? Indicate the genotypes of each phenotypes.

Answer 13

Incomplete dominance

Black BB, white bb, grey Bb

Question 14

In a shortorn cattle, 3 coat colors occur: red, roan and white. Mating red and red or white and white produces only red or only white offsprings. Mating roan with roan produces roan, red and white in 1:2:1 proportions. What is the genotype of the roan?

Answer 14

RR’

Question 15

In a shortorn cattle, 3 coat colors occur: red, roan and white. Mating red and red or white and white produces only red or only white offsprings. Mating a roan with white produces 20 calves. Predict the most likely phenotypes and their proportions of these offsprings? What is the inheritance?

Answer 15

Co-dominance

1/2 R’R’ white, 1/2 R’R roan

Question 16

In a labrador, dominant allele E- is required to produce pigment, dogs with 2 recessive alleles are golden (ee). A second gene give a black B- color when dominant and a brown bb when recessive. Which genotype gives brown coat?

Answer 16

Eebb

Question 17

Achondroplastic dwarfism is caused by heterozygous Aa and the homozygous recessive aa is lethal. Select the genotypes of the possible children from a cross between heterozygous achondro. parents.

Answer 17

Aa and AA, aa zygote will not be born

Question 18

In radishes, shape may be long, round or oval. Crosses between round and oval made 199 round and 203 oval offspring. Crosses between oval and oval made 121 long, 243 oval and 119 round. Which phenotype is the heterozygote?

Answer 18

Oval

Question 19

In radishes, shape may be long, round or oval. Crosses between round and oval made 199 round and 203 oval offspring. Crosses between oval and oval made 121 long, 243 oval and 119 round. What is the inheritance?

Answer 19

Incomplete dominance

Question 20

A cross of two erminette produces 22 erminette, 14 black and 12 white chickens. What type of inheritance is this?

Answer 20

Co-dominance (erminette is fleckered white and black)