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13. Mendelian Genetics

Test Crosses

13. Mendelian Genetics

Test Crosses

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Jason Amores Sumpter

Steps to Performing a Test Cross

Steps to Performing a Test Cross

Jason Amores Sumpter

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Animation: Testcross in "MendAliens"

Animation: Testcross in "MendAliens"

Monohybrid Test Cross (Mendel's Experiments)

Monohybrid Test Cross (Mendel's Experiments)

Test Crosses | Genetics

Test Crosses | Genetics

Practice this topic

Multiple Choice

A single gene test cross is conducted to determine the genotype of a pea plant that shows the dominant phenotype for height (T = tall, t = short). If all offspring of the cross show the dominant phenotype, then the genotype of the unknown parent is _______.

a) TT.

b) tT.

c) Tt.

d) tt.

Has a video solution.

Multiple Choice

You want to determine the pea color genotype of a pea plant with yellow peas. You conduct a test cross with your mystery pea plant. The test cross results in 50% of the offspring possessing yellow peas and 50% of the offspring possessing green peas. What is the genotype for pea color of the mystery parent?

a) YY.

b) Yy.

c) yy.

d) None of the above.

Has a video solution.

Multiple Choice

What is indicated when a single-character testcross yields offspring that all have the dominant phenotype?

Multiple Choice

A gray-bodied, vestigial-winged fly is crossed with a black-bodied, normal-winged fly. The F₁ progeny is testcrossed. Among the resulting offspring, __________ is a parental type, and __________ is a recombinant type.

Multiple Choice

To identify the genotype of a yellow-seeded pea plant as either homozygous dominant (YY) or heterozygous

(Yy), you could do a test cross between your mystery plant and a plant with a genotype of _______.

Has a video solution.

Textbook Question

Two black female mice are crossed with a brown male. In several litters, female I produced 9 black offspring and 7 brown; female II produced 57 black offspring. What deductions can you make about the inheritance of black and brown coat color in mice? What are the genotypes of the parents?

Has a video solution.

Textbook Question

In flies, small wings are recessive to normal wings. If a cross between two flies produces 8 small-wing offspring and 28 normal-wing offspring, what are the most likely genotypes of the parents? (Use S to represent the normal-wing allele and s to represent the short-wing allele.)

Has a video solution.

Textbook Question

In flies, small wings are recessive to normal wings. If a cross between two flies produces 8 small-wing offspring and 28 normal-wing offspring, what are the most likely genotypes of the parents? (Use S to represent the normal-wing allele and s to represent the short-wing allele.)

Has a video solution.

Textbook Question

The smooth feathers on the back of the neck in pigeons can be reversed by a mutation to produce a 'crested' appearance in which feathers form a distinctive spike at the back of the head. A pigeon breeder examined offspring produced by a single pair of non-crested birds and recorded the following: 22 non-crested and 7 crested. She then made a series of crosses using offspring from the first cross. When she crossed two of the crested birds, all 20 of the offspring were crested. When she crossed a non-crested bird with a crested bird, 7 offspring were non-crested and 6 were crested. For these three crosses, provide genotypes for parents and offspring that are consistent with these results.

Has a video solution.

Textbook Question

In 1981, a stray black cat with unusual rounded, curled-back ears was adopted by a family in California. Hundreds of descendants of the cat have since been born, and cat fanciers hope to develop the curl cat into a show breed. Suppose you owned the first curl cat and wanted to develop a true-breeding variety. How would you determine whether the curl allele is dominant or recessive? How would you obtain true-breeding curl cats? How could you be sure they are true-breeding?

Has a video solution.

Textbook Question

In 1981, a stray black cat with unusual rounded, curled-back ears was adopted by a family in Lakewood, California. Suppose you owned the first curl cat and wanted to breed it to develop a true-breeding variety. Describe tests that would determine whether the curl gene is dominant or recessive and whether it is autosomal or sex-linked. Explain why you think your tests would be conclusive. Describe a test to determine that a cat is true-breeding.

Has a video solution.

Textbook Question

You have crossed two Drosophila melanogaster individuals that have long wings and red eyes—the wild-type phenotype. In the progeny, curved wings and lozenge eyes mutant phenotypes appear as follows: What is the genotype of the male parent?

Has a video solution.

Textbook Question

You have crossed two Drosophila melanogaster individuals that have long wings and red eyes—the wild-type phenotype. In the progeny, curved wings and lozenge eyes mutant phenotypes appear as follows: What is the genotype of the female parent?

Has a video solution.

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