Question

1. in humans, the allele for tongue rolling (r) is dominant to the allele for non - tongue rolling (r). a man who is a non - roller marries and has offspring with a woman who is heterozygous.

a. what is the mother’s genotype? ____________
b. what is the father’s genotype? ____________
c. what is the chance of having a nonrolling child? ____________
d. what is the chance of having a rolling child? ____________

1. in tomatoes, red fruit (r) is dominant to yellow fruit (r). cross a homozygous red tomato plant to a heterozygous plant.

a. what is the genotypic ratio? ____________
b. what is the phenotypic ratio? ____________
c. what is the chance of for red fruit? __________ yellow fruit? __________

1. in cattle, the hornless condition (h) is dominant and the horned condition (h) is recessive. a bull without horns is crossed with a cow with horns. of the four offspring, 1 is horned and 3 are hornless.

a. what is the genotype of the bull? ____________
b. what is the genotype of the cow? ____________
c. what is the genotypic ratio? ____________
d. what is the phenotypic ratio? ____________

1. in humans widow’s peak (h) is dominant over straight hairline (h). a man with a straight hairline has children with a women with two alleles for widow’s peak.

a. what is the chance that any offspring would have a widow’s peak? ____________
b. what is the chance that any offspring would not have a widow’s peak? ____________
c. genotypic ratio? ____________
matching vocabulary
______ 9. genotypes made from the same alleles
______ 10. different forms of genes for a single trait
______ 11. gene that is always expressed
______ 12. gene that is only expressed in the homozygous state
______ 13. genotype made of two different alleles.
a. alleles
b. dominant
c. heterozygous
d. homozygous
e. recessive

Explanation:

5.

Step1: Determine mother's genotype

The mother is heterozygous. So her genotype is Rr.

Step2: Determine father's genotype

The father is a non - roller. Since non - rolling is recessive, his genotype is rr.

Step3: Calculate probability of non - rolling child

The cross is Rr x rr. Using a Punnett - square, the possible genotypes are Rr and rr in a 1:1 ratio. The probability of having a non - rolling child (rr) is 50% or 1/2.

Step4: Calculate probability of rolling child

The probability of having a rolling child (Rr) is 50% or 1/2.

6.

Step1: Identify genotypes of parents

The homozygous red tomato plant has genotype RR and the heterozygous plant has genotype Rr.

Step2: Determine genotypic ratio

The cross is RR x Rr. The possible genotypes are RR and Rr in a 1:1 ratio. So the genotypic ratio is 1 RR : 1 Rr.

Step3: Determine phenotypic ratio

Since both RR and Rr result in red fruit, the phenotypic ratio is 100% red : 0% yellow or 1:0.

Step4: Calculate probabilities of fruit color

The chance of red fruit is 100% or 1, and the chance of yellow fruit is 0% or 0.

7.

Step1: Determine cow's genotype

The cow has horns, so its genotype is hh.

Step2: Determine bull's genotype

Since some offspring are horned (hh), the bull without horns must be heterozygous, so its genotype is Hh.

Step3: Calculate genotypic ratio

The cross is Hh x hh. The possible genotypes are Hh and hh in a 1:1 ratio. So the genotypic ratio is 1 Hh : 1 hh.

Step4: Calculate phenotypic ratio

The phenotypic ratio of hornless (Hh) to horned (hh) is 1:1.

8.

Step1: Identify parents' genotypes

The man with a straight hairline has genotype hh, and the woman with two alleles for widow's peak has genotype HH.

Step2: Calculate probability of widow's peak offspring

The cross is HH x hh. All offspring will have genotype Hh, so the chance of having a widow's peak offspring is 100% or 1.

Step3: Calculate probability of non - widow's peak offspring

The chance of having a non - widow's peak offspring is 0% or 0.

Step4: Determine genotypic ratio

The genotypic ratio is 1 Hh : 0 hh : 0 HH or simply 1 Hh.

Matching Vocabulary

1. Genotypes made from the same alleles: D. homozygous
2. Different forms of genes for a single trait: A. alleles
3. Gene that is always expressed: B. dominant
4. Gene that is only expressed in the homozygous state: E. recessive
5. Genotype made of two different alleles: C. heterozygous

Answer:

5.
A. Rr
B. rr
C. 50% or 1/2
D. 50% or 1/2
6.
A. 1 RR : 1 Rr
B. 1 red : 0 yellow
C. 100% or 1, 0% or 0
7.
A. Hh
B. hh
C. 1 Hh : 1 hh
D. 1 hornless : 1 horned
8.
A. 100% or 1
B. 0% or 0
C. 1 Hh

1. D. homozygous
2. A. alleles
3. B. dominant
4. E. recessive
5. C. heterozygous