The Biology Project
Department of Biochemistry and Molecular Biophysics
University of Arizona

A. None

B. 1/4

C. 1/2

D. 3/4

E. All

A. the alleles segregate during meiosis.

B. each allele contains two mutations.

C. the alleles are identical.

D. the alleles are incompletely dominant.

E. only recessive traits are scored.

Problem 3) Mendel's "Experiment 1"

In Mendel's "Experiment 1," true-breeding pea plants with spherical seeds were crossed with true-breeding plants with dented seeds. (Spherical seeds are the dominant characteristic.) Mendel collected the seeds from this cross, grew F1-generation plants, let them self-pollinate to form a second generation, and analyzed the seeds of the resulting F2 generation. The results that he obtained, and that you would predict for this experiment are:

A.	1/2 the F1 and 3/4 of the F2 generation seeds were spherical.
B.	1/2 the F1 and 1/4 of the F2 generation seeds were dented.
C.	All of the F1 and F2 generation seeds were spherical.
D.	3/4 of the F1 and 9/16 of the F2 generation seeds were spherical.
E.	All the F1 and 3/4 of the F2 generation seeds were spherical.

Problem 4) A cross of F1-hybrid plants

A genetic cross between two F1-hybrid pea plants for spherical seeds will yield what percent spherical-seeded plants in the F2 generation? (Recall, spherical-shaped seeds are dominant over dented seeds.)

A. 100%

B. 75%

C. 50%

D. 25%

E. 0%

Problem 5) Another F1-hybrid cross

A genetic cross between two F1-hybrid pea plants having yellow seeds will yield what percent green-seeded plants in the F2 generation? Yellow seeds are dominant to green.

A. 0%

B. 25%

C. 50%

D. 75%

E. 100%

Problem 6) Predicting the dominant allele

When true-breeding tall stem pea plants are crossed with true-breeding short stem pea plants, all of the _________ plants, and 3/4 of the __________ plants had tall stems. Therefore, tall stems are dominant.

A. F1, F2.

B. G1, G2.

C. parental, F2.

D. F2, parental.

E. P1, P2

A. y

B. Y

C. yy

D. YY

E. Yy

Problem 8) Predicting the results of a test cross

A test cross is used to determine if the genotype of a plant with the dominant phenotype is homozygous or heterozygous. If the unknown is homozygous, all of the offspring of the test cross have the __________ phenotype. If the unknown is heterozygous, half of the offspring will have the __________ phenotype.

A. dominant, incompletely dominant

B. recessive, dominant

C. dominant, epistatic

D. codominant, complimentary

E. dominant, recessive

Problem 9) Incomplete dominance

In Mendel's experiments, if the gene for tall (T) plants was incompletely dominant over the gene for short (t) plants, what would be the result of crossing two Tt plants?

A. 1/4 would be tall; 1/2 intermediate height; 1/4 short

B. 1/2 would be tall; 1/4 intermediate height; 1/4 short.

C. 1/4 would be tall; 1/4 intermediate height; 1/2 short.

D. All the offspring would be tall.

E. All the offspring would be intermediate.

Problem 10) Disappearance of parental phenotypes in the F1 generation

A genetic cross of inbred snapdragons with red flowers with inbred snapdragons with white flowers resulted in F1-hybrid offspring that all had pink flowers. When the F1 plants were self-pollinated, the resulting F2-generation plants had a phenotypic ratio of 1 red: 2 pink: 1 white. The most likely explanation is:

A.	pink flower color is epistatic to red flower color.
B.	pink flowers are the result of a blending of the red and white genotypes.
C.	flower color is due to 2 or more complementary genes.
D.	heterozygous plants have a different phenotype than either inbred parent because of incomplete dominance of the dominant allele.
E.	flower color inheritance in snapdragons does not behave as a Mendelian trait.

Problem 11) Codominant alleles: The human ABO markers

Human blood type is determined by codominant alleles. There are three different alleles, known as I^A, I^B, and i. The I^A and I^B alleles are co-dominant, and the i allele is recessive.

The possible human phenotypes for blood group are type A, type B, type AB, and type O. Type A and B individuals can be either homozygous (I^AI^A or I^BI^B, respectively), or heterozygous (I^Ai or I^Bi, respectively).

A woman with type A blood and a man with type B blood could potentially have offspring with which of the following blood types?

A. type A

B. type B

C. type AB

D. type O

E. all of the above

A. pleiotropic

B. codominant

C. epistatic

D. lethal

E. sex-linked