B6F

If several pea plants with the genotype TTYy are crossed with pea plants with the genotype Ttyy, what percentage of the offspring will be expected to have the TTYy allele combination?

• 25%

• 40%

• 50%

• 75%

In cocker spaniels the allele for a black coat color (B) is dominant over the allele for a brown coat color (b). If a brown cocker spaniel is crossed with a heterozygous black cocker spaniel, which of the following genotypic ratios can be expected?

• 0 BB: 2 Bb: 2bb

• 1 BB: 2 Bb: 1 bb

• 2 BB: 0 Bb: 2 bb

• 2 BB: 1 Bb: 0 bb

In the 1860's Gregor Mendel performed numerous dihybrid crosses between pea plants. Dihybrid crosses involve the study of the inheritance patterns related to two different traits. In guinea pigs the allele for black fur (B) is dominant over the allele for brown fur (b), and the allele for short fur (F) is dominant over the allele for long fur (f). What percentage of the offspring from a BbFf x bbff cross would be expected to be heterozygous for both traits?

• 0%

• 25%

• 50%

• 100%

Tomato plants usually have hairy stems. Hairless stems are present in tomato plants that are homozygous recessive for this trait. If the stem characteristics are determined by a single gene, what is the expected outcome of crossing two tomato plants that are heterozyous for hairy stems?

• 75% hairy stems: 25% hairless stems

• 100 % hairy stems

• 100 % hairless stems

• 50% hairy stems, 50% hairless stems

Facial dimples and free earlobes are both considered dominant human traits. What are the expected phenotypes of the offspring of a female with dimples and free earlobes (DDFf) and a male with no dimples and attached earlobes (ddff)?

• 50% with dimples and free earlobes and 50% with dimples and attached earlobes

• 50% with dimples and free earlobes and 50% with no dimples and attached earlobes

• 75% with dimples and free earlobes and 25% with no dimples and attached earlobes

• 75% with dimples and attached earlobers and 25% with no dimples and free earlobes

Normal fruit flies have brownish-yellow bodies, and this body color is dominant. A mutation in the gene for body color can produce flies with an ebony body color. A homozygous normal fruit fly (EE) is crossed with a homozygous ebony fruit fly (ee). What is the predicted outcome of this genetic cross?

• all of the offspring will have ebony bodies

• of the offspring, 75% will have brownish-yellow bodies, and 25% will have ebony bodies

• all of the offspring will have brownish-yellow bodies

• of the offspring, 75% will have ebony bodies and 25% will have brownish-yellow bodies

The four butterflies in the illustrations represent the offspring of the F1 generation. Which statement is best supported by the phenotypes of these offspring?

• the F1 generation is composed of only males

• two of the offspring in the F1 generation will not be able to reproduce

• the F1 generation is the result of a dihybrid cross

• two of the offspring in the F1 generation will experience a spontaneous mutation

Chickens can have different types of feathers. Frizzled feathers curl toward a chicken's head. Assume that feather type is determined by a single gene and that the allele for frizzles feathers is dominant over the allele for straight feathers. In a cross between two chickens with straight feathers, what percentage of the offspring can be expected to have frizzled feathers?

• 0%

• 25%

• 50%

• 100%

Albinism is an autosomal recessive condition. Which circle graph shows the genotype probability when an albino female mates with a male that is heterozygous for the albinism trait?

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In Holstein cattle the allele for black hair color (B) is dominant over the allele for red hair color (b), and the allele for polled (P), or lacking horns, is dominant over the allele for having horns (p). What is the expected phenotypic ratio of the offspring of a BbPp x BbPp cross if these alleles sort independently?

• 16 black/polled: 0 black/horned, 0 red/polled, 0 red/horned

• 12 black/polled, 0 black/horned, 0 red/polled, 4 red/horned

• 4 black/polled, 4 black/horned, 4 red/polled, 4 red/horned

• 9 black/polled, 3 black/horned, 3 red/polled, 1 red/horned