Exam 19: Introduction to Genetics

The F ₂ phenotypic ratio of a monohybrid cross is

Gray is homozygous while blue is a heterozygous form of a semi-lethal gene. Give the ratio of the offspring produced in the cross of two blues.

The genotype of the parent at #1 is

The chance of producing an offspring of genotype Aa BB cc from a cross of Aa Bb Cc with Aa Bb Cc is

If a child has blood type AB, the parents

Individuals with the genotype Gg Hh Ii Jj will produce how many different kinds of gametes?

In cocker spaniels, black coat color (B) is dominant over red (b) , and solid color (S) is dominant over spotted (s) . If a red, spotted male was crossed with a black, solid female and all the offspring from several crosses expressed only the dominant traits, the genotype of the female would be

Horses In horses, black coat color is influenced by the dominant allele ( B ) and chestnut coat color by the recessive allele ( b ). Trotting gait is due to a dominant gene ( T ), pacing gait to the recessive allele ( t ). Use this information to answer the following question(s). In the horses example above, if a homozygous black trotter is crossed to a chestnut pacer, (a) what will be the appearance of the F ₁ and F ₂ generations? (b) which phenotype will be the most common? (c) which genotype will be the most common? (d) which of the potential offspring will be certain to breed true?

Which of the following genotypes is homozygous?

In the late 1920s, a mutation occurred in many silver fox farms around the world. The fox farms that sold expensive furs were proud of the quality of their furs, and each advertised that it had the best and most pure breed of all the fox farms. The new mutations produced a "platinum" coat pattern that was commercially desirable, so the farms crossed them to get more. The results of their breeding experiments were as follows: (1) silver x silver → all silver offspring; (2) silver x platinum → equal numbers of silver and platinum; (3) platinum x platinum → 2 platinum for each silver offspring. Explain.

Homozygotes with the genotype Hb^S/Hb^S have

In poultry, rose comb is controlled by a dominant allele and its recessive allele controls single comb. (a) Give the genotype and phenotype produced from crossing a pure-breeding, rose comb chicken with a pure-breeding, single comb chicken. (b) Give the results of the backcross of the F ₁ hybrid with both pure-breeding parents.

Blood types (A, B, and O) are controlled by

An individual with a genotype of Aa Bb CC is able to produce how many different kinds of gametes?

Selecting the Exception Four of the five answers listed below are pure-breeding. Select the exception.

A given chromosome and its genes may end up in any of ____ gametes.

Garden Peas In garden peas, one pair of alleles controls the height of the plant and a second pair of alleles controls flower color. The allele for tall ( D ) is dominant to the allele for dwarf ( d ), and the allele for purple ( P ) is dominant to the allele for white ( p ). Use this information to answer the following question(s). In the garden peas example above, a tall plant with purple flowers crossed with a tall plant with purple flowers produces 3/4 tall purple flowers and 1/4 tall white flowers. What is the genotype of the parents?