KA - Classical Genetics Unit Test

In humans, the gene for curly hair (H) is incompletely dominant to the gene for straight hair (h). Individuals that are heterozygous (Hh) have wavy hair. Two wavy-haired heterozygous parents have a child. What is the likeliness that the child will have wavy hair?

1/2

Sickle-cell anemia is a recessive trait in humans. In order to express the disease, an affected individual must inherit two recessive alleles (ss). What is the probability that the offspring of two heterozygous parents will also be heterozygous?

1/2

In a pea plant, tall (T) is dominant to short (t), and green peas (G) are dominant to yellow peas (g). A tall plant with yellow peas (Ttgg) is crossed with a short plant with green peas (ttGg). Both the T and G traits assort independently from one another. What is the chance that the offspring will be short with yellow peas?

1/4

Hemophilia is an X-linked recessive trait. A non-hemophiliac father and a hemophiliac mother have a son. What is the percent chance that the son will be a hemophiliac?

100%

The pedigree below tracks Duchenne Muscular Dystrophy (DMD) through several generations. DMD is an X-linked recessive trait. If individuals I-1 and I-2 had another son, what is the chance that he would have DMD?

100%

In chickens, the allele for a pea comb (A) is dominant to the allele for a single comb (a). A mother with the genotype Aa and a father with the genotype Aa produce an offspring. What is the percent chance that the offspring will have a single comb?

25%

In humans, three alleles affect blood type. The A and B alleles are codominant, and the O allele is recessive. An AB blood type father has children with an A blood type mother (genotype AO). What are the chances that their children will have AB type blood?

25%

The pedigree below tracks the presence of attached earlobes through a family's generation. Having attached earlobes is an autosomal recessive trait. If individuals I-1 and I-2 had a fourth child, what is the chance that the child would have attached earlobes?

50%

Coat color in mice depends on three alleles. A scientist crosses a black mouse (c^b c) with an agouti mouse (Cc^b). What are the predicted phenotypes of their offspring?

50% of the offspring will have agouti coats, and 50% will have black coats.

A gene for corn has two alleles, one for yellow kernels and one for white kernels. A farmer mates yellow and white corn. All of the offspring have a nearly even mix of yellow and white kernels. Which type of inheritance most likely explains the relationship between the two alleles? Choose 1 answer:

Codominance

The pedigree below tracks the presence of dimples through a family's generation. Having dimples is an autosomal dominant trait. What is the phenotype of individual III-4?

Dimples

Which of the following are true of dominant and recessive alleles?

Dominant alleles mask the expression of recessive alleles. Dominant and recessive alleles can be found in the same individual.

The pedigree below tracks the presence of dimples through a family's generation. Having dimples is an autosomal dominant trait. Which of the following individuals is correctly matched with its genotype?

III-2 --> Dd

A black sheep is bred with a white sheep. All of their offspring have a phenotype of gray coats. What is the most likely pattern of inheritance for coat color in sheep?

Incomplete dominance

Which of the following is true regarding sex chromosome aneuploidy in humans?

Male sex chromosome aneuploidy can affect either the X or Y chromosome.

Duchenne muscular dystrophy (DMD) is an X-linked recessive condition that causes rapid muscle degeneration. DMD occurs in approximately 1 in every 3500 males, but it rarely affects females. Which statement most accurately explains why DMD affects males more often than females?

Males only have one copy of the X chromosome.

In buffalo, being boring (B) is dominant to being busy (b). A true-breeding, busy male is crossed with a true-breeding, boring female. What are the possible genotypes of their offspring?

Only Bb

Both pleiotropy and polygenic inheritance are key examples of Non-Mendelian inheritance. Which of the following answer choices is true?

Pleiotropy is when one gene affects multiple characteristics (e.g. Marfan syndrome).

In humans, the ability to taste the bitter chemical PTC is controlled by a single gene. The tasting gene (T) is dominant to the non-tasting gene (t). Which of the following genotypes is correctly labeled?

TT - Dominant homozygous

A dog breeder crosses two dogs that are heterozygous for brown coats. Some of the puppies have brown coats, and some have black coats. Assuming that coat color is controlled by a single gene, which of the following statements is most likely true?

The allele for brown coat is dominant to the allele for black coat.

A woman who has a sex-linked recessive trait has a son with a man who does not have that trait. Which of the following is true about their son?

There is a 100% chance he will be affected.

In a species of birds, having wide wings (W) is dominant to having thin wings (w). Which of the following genotypes is INCORRECTLY labeled?

Ww - homozygous dominant

The pedigree below tracks Duchenne Muscular Dystrophy (DMD) through several generations. DMD is an X-linked recessive trait. What is the genotype of individual II-2?

X^D, X^d

In chickens, the allele for black feathers (A) is dominant over the allele for red feathers (a). Which of the following pairs of terms are correctly matched?

aa - genotype; red feathers - phenotype

In pea plants, the allele for smooth pods (S) is dominant over the allele for constricted pods (s). Which of the following pairs of terms are correctly matched?

ss - genotype; constricted pod - phenotype

In horses, black coloring (B) is dominant, and chestnut coloring (b) is recessive. A homozygous black horse crosses with a chestnut horse. What percentage of offspring are expected to be chestnut?

0%

Ocular albinism is an X-linked recessive trait that causes a lack of pigmentation in the eyes. A father with ocular albinism and mother without the trait have a daughter. What is the percent chance that the daughter will have ocular albinism?

0%

In snakes, being rude (R) is dominant to being respectful (r), and being sneaky (S) is dominant to being sincere (s). A female snake that is homozygous recessive for both the r and s trait is mated with a male snake that is homozygous dominant for both traits (R and S). Both the R and S traits assort independently from one another. What is the probability that they will have an offspring that is respectful and sincere?

0/16

In rabbits, brown fur (B) is dominant to white fur (b) and short fur (H) is dominant to long fur (h). A brown, long-furred rabbit (Bbhh) is crossed with a white, short-furred rabbit (bbHh). Both the B and H traits assort independently from one another. What percentage of the offspring will be brown with long fur?

25%

The pedigree below tracks Duchenne Muscular Dystrophy (DMD) through several generations. DMD is an X-linked recessive trait. If individual II-3 has a child with a carrier woman, what is the percent chance that the child will be a daughter with DMD?

25%

The pedigree below tracks the presence of dimples through a family's generation. Having dimples is an autosomal dominant trait. If individuals II-1 and II-2 have a fourth child, what is the probability that the child will have dimples?

50%

When white-coated cattle (W) are mated with red-coated cattle (R), the offspring are roan (WR), meaning their coats contain both white and red hairs. This is an example of codominance. A farmer breeds two roan cattle with one another. What is the chance that their offspring will be roan?

50%

In camellia flowers, petal color is controlled by codominance. When a red flower is crossed with a white flower, all of the offspring are covered in both red and white petals. A scientist crosses a red flower (RR) with a red-and-white (RW) flower. What are the predicted phenotypes of their offspring?

50% percent of the offspring will be red, and 50% percent of the offspring will be red-and-white

The pedigree below tracks the presence of dimples through a family's generation. Having dimples is an autosomal dominant trait. If individual III-3 married a woman who was heterozygous for dimples, what is the percent chance their children will have dimples?

75%

In dogs, being clumsy (C) is dominant to being cool (c), and being dazzling (D) is dominant to being docile (d). A female dog that is heterozygous for both the C and D trait is mated with a male dog that is also heterozygous for both traits. Both the C and D traits assort independently from one another. What is the probability that they will have an offspring that is clumsy and dazzling?

9/16

Which of the following answer choices would be a sex chromosome aneuploidy in a human?

An egg contains two X chromosomes.

The pedigree below tracks the presence of attached earlobes through a family's generation. Having attached earlobes is an autosomal recessive trait. What is the genotype of individual I-1?

Ee

The pedigree below tracks the presence of attached earlobes through a family's generation. Having attached earlobes is an autosomal recessive trait. What is the genotype of individual II-3?

Ee

A female fish is homozygous dominant for both fancy fins (F) and shiny scales (S). She is crossed with a male who is heterozygous for both traits. What are the genotypes of these fish? (female; male)

FFSS; FfSs

Which type of non-Mendelian inheritance is depicted based on the Punnett square results above?

Lethal allele

Hunter syndrome is a progressively debilitating recessive disorder that is inherited on the X chromosome. A father without Hunter syndrome and an unaffected carrier mother have a child. Which of the following statements is true?

No daughter they have will be affected.

Human eye colors are found on a spectrum that ranges from completely pigmented (dark brown eyes) to a complete lack of pigment (light blue eyes). Which type of non-Mendelian inheritance does human eye color exemplify and why?

Polygenic inheritance; it involves multiple genes coding for a trait that falls within a wide spectrum

In the fruit fly Drosophilia, eye color is sex-linked. The allele for red eyes is dominant (X^W) and the allele for white eyes is recessive (X^w) A scientist crosses two red-eyed flies and notice that half of their male offspring have white eyes. What are the genotypes of the parents?

X^W, X^w; X^W, Y

In humans, the ability to break down lactose as an adult (known as lactase persistence) is dominant (L) to the inability to break down lactose as an adult (known as lactose intolerance), which is recessive (l). Which of the following genotype and phenotype combinations is correctly labeled?

ll - homozygous recessive - lactose intolerance

A male bird is homozygous recessive for both wacky wings (w) and flashy feathers (f). He is crossed with a female who is homozygous dominant (normal wings and normal feathers) for both traits. What are the genotypes of these birds? (male; female)

wwff; WWFF