Question 1

A scientist wants to determine whether a yellow-seeded pea plant is homozygous dominant ($$YY) or $$heterozygous ($$Yy). $$Which of the following crosses should the scientist perform to reveal the genotype of the mystery plant?

Accepted Answer

Cross the mystery plant with a homozygous recessive ($$yy) $$plant.

Question 2

In a test cross between a pea plant with genotype $$Yy$$ and a plant with genotype $$yy$$, what is the expected phenotypic ratio of the offspring?

Accepted Answer

$$1:1$$ ratio of yellow to green seeds

Question 3

If a test cross between a yellow-seeded pea plant and a $$yy$$ plant produces all yellow-seeded offspring, what is the genotype of the yellow-seeded parent?

Accepted Answer

$$YY$$

Question 4

A test cross is performed between a tall pea plant (dominant, $$T) $$and a short pea plant ($$tt). If $$all offspring are tall, what is the genotype of the tall parent?

Accepted Answer

$$TT$$

Question 5

You perform a test cross between a yellow-seeded pea plant and a green-seeded pea plant. The offspring are 50% yellow and 50% green. What is the genotype of the yellow-seeded parent?

Accepted Answer

$$Yy$$

Question 6

Why are test crosses typically performed with homozygous recessive individuals?

Accepted Answer

Because the homozygous recessive genotype reveals the presence of recessive alleles in the mystery parent.

Question 7

A test cross between a plant with unknown genotype and a homozygous recessive plant results in all offspring displaying the dominant phenotype. What can you conclude about the genotype of the unknown parent?

Accepted Answer

The unknown parent is homozygous dominant.

Question 8

If a test cross yields a 1:1 ratio of dominant to recessive phenotypes in the offspring, what was the genotype of the mystery parent?

Accepted Answer

Heterozygous

Question 9

A yellow-seeded pea plant is crossed with a green-seeded pea plant. All offspring are yellow. What is the most likely genotype of the yellow-seeded parent?

Accepted Answer

$$YY$$

Question 10

In a test cross, what is the expected genotypic ratio of offspring when a heterozygous dominant plant ($$Yy) is $$crossed with a homozygous recessive plant ($$yy$$)?

Accepted Answer

$$1:1$$ ratio of $$Yy to$$ $$yy$$

Question 11

A test cross is performed and all offspring display the recessive phenotype. What does this indicate about the genotype of the mystery parent?

Accepted Answer

The mystery parent is homozygous recessive.

Question 12

Which of the following best describes the purpose of a test cross in genetics?

Accepted Answer

To determine the genotype of an individual with a dominant phenotype.

Question 13

A test cross between a tall pea plant and a short pea plant produces 100% tall offspring. Which of the following is the most likely genotype of the tall parent?

Accepted Answer

$$TT$$

Question 14

If a test cross between a yellow-seeded pea plant and a green-seeded pea plant produces 100% yellow-seeded offspring, what is the genotype of the yellow-seeded parent?

Accepted Answer

$$YY$$

Question 15

A test cross is performed between a plant with genotype $$Tt$$ and a plant with genotype $$tt. $$What percentage of the offspring are expected to be tall?

Accepted Answer

50%

Test Crosses and Determining Genotype in Mendelian Genetics

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