Biology Module 8 (Study Guide Questions)

Three pea plants have the following alleles for yellow (“Y”) and green (“y”) peas. What is the genotype and phenotype of each? Note whether they are homozygous or heterozygous.
a. YY
b. Yy
c. yy
a. Genotype: homozygous; Phenotype: yellow
b. Genotype: heterozygous; Phenotype: yellow
c. Genotype: homozygous; Phenotype: green

What process causes gametes to have only one allele, since other human cells have two of each allele?
Meiosis separates the two alleles

A pea plant which is homozygous in the dominant, axial flower allele (“A”) is crossed with a pea plant that is heterozygous in that allele. What are the possible genotypes and phenotypes, along with their percentage chances, for the offspring?
50% of the offspring have the “AA” genotype and 50% have the “Aa” genotype.
100% have the axial flower phenotype

A woman is a heterozygous in the ability to roll her tongue when extended. If she marries a man who cannot roll his tongue, what percentage of their children will be able to roll their tongues? Remember the allele for being able to roll your tongue is dominant.
50% of the children will be able to roll their tongue

Give the possible phenotypes and percentage chance for each in the dihybrid cross between a pea plant that is homozygous in producing smooth, yellow peas and a pea plant that produces wrinkled, green peas. The smooth and yellow alleles are dominant.
100% of the offspring have the “SsYy” genotype and the smooth, yellow phenotype

Give the possible phenotypes and the percentage chance for each in the dihybrid cross between a pea plant that is heterozygous in producing smooth, yellow peas and another with the same genotype.
smooth, yellow peas 56.25%
smooth, green peas 18.75%
wrinkled, yellow peas 18.75%
wrinkled, green peas 6.25%

In fruit flies, the color of the eye is a genetic trait that is sex-linked. What is the percentage of males that will have white eyes when a heterozygous, red-eyed female is crossed with a white-eyed male? What is the percentage of females that will have white eyes from the same cross?
50% of the females will be white-eyed
50% of the males will be white-eyed

In the case of the fruit fly eye color again, what must be the genotype of a male fly if, when crossed with a heterozygous female, there is no possibility of having a female with white eyes?
XᴿY

If a gamete has two alleles for the same genetic trait, what type of genetic disorder will result in a zygote formed with this gamete?
Change in chromosome number

A person carries a genetic disorder but does not have the disorder. How is that possible?
The genetic disorder must be recessive

Do sex-linked genetic disorders affect men and women the same? If not, which sex is affected more and why?
Sex-linked disorder affect men more frequently than women. This is because men have only one allele in sex-linked traits.

Two individuals have the exact same genotype for a certain trait, but they are not identical when it comes to that trait. How is this possible?
While the genetics are the same, the environmental and spiritual factors were probably different.

A woman with type O blood marries a man with type AB blood. What blood types are possible for their children? What is the percentage chance for each blood type?
A 50%
B 50%

IF a person has type B blood, what are the possible genotypes for that person? Include the possible genotypes related both to the type of blood as well as the Rh-factor.
BB or BO

What term do we use to refer to genetic traits that are governed by more than one set of genes?
Polygenetic inheritance