Genetics Test Review
1,) In elephants short ears (s) are recessive and long ears (S) are dominant.
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If the offspring produced was homozygous dominant for the trait what would the genotype and
phenotype be?
If the offspring produced was Heterozygous for the trait what would the genotype and
phenotype be?
If the offspring was homozygous recessive what would the genotype and phenotype be?
2,) In dogs, wire hair (S) is dominant to smooth (s). In a cross of a homozygous wire-haired dog with a
smooth-haired dog, what will be the phenotype and genotype of the F1 generation?
3,) In apples, red fruit (R) is dominant over green fruit (r). An apple tree that is homozygous for red fruit
is crossed with a plant that has green fruit. What would be the genotypes and phenotypes of the F1
generations?
4, In humans, being a tongue roller (R) is dominant over non-roller (r). A man who is a non-roller marries
a woman who is heterozygous for tongue rolling. What would the genotypes and phenotypes of the
offspring be? What percentage of the offspring will be tongue rollers?
5, In pea plants, spherical seeds (S) are dominant to dented seeds (s). In a genetic cross of two plants
that are heterozygous for the seed shape trait. What will the genotypes of the offspring be? What
fraction of the offspring should have spherical seeds?
6, In plants green pods (C) are dominant to yellow pods (c). A plant that is heterozygous for green pods
is crossed with a plant that has yellow pods. What are the possible genotypic and phenotypic ratios in
the offspring resulting from this cross? What percentage of the offspring will be Heterozygous for green
pods.
7, In pigs, the allele for short hair is dominant (H). If all the pigs are born short haired what are the
possible genotypes of the parents? (There are two possible combinations.)
8, In humans brown hair (B) is dominant over blonde hair coloring (b). Cross a homozygous brown
haired person to a homozygous blonde haired person. What are the phenotypes? What percentage
of the offspring will be brown haired?
9, A dog of unknown genotype is test-crossed (meaning it is crossed with a recessive tt dog). Of the
offspring, 860 have spots and 900 are solid colored. What is the genotype of the unknown parent, is
it TT or Tt? Show the cross to prove it.
10, Suppose that black hair (B) is dominant over blonde hair (b) and brown eyes (E) are dominant over
blue eyes (e).
A father that is heterozygous for black hair and has blue eyes is crossed with his wife that is homozygous
recessive for blonde hair and is Heterozygous for brown eyes. What are the offspring’s genotypic and
phenotypic ratios? Use the corresponding dihybrid cross to verify.
11, In rabbits, gray hair (G) is dominant to white hair (g), and black eyes (B) are dominant to red eyes
(b).
A male that is homozygous recessive for hair color and has red eyes is crossed with a female rabbit that
is Heterozygous for both hair and eye color. What are the genotypic and phenotypic ratios of the
offspring?