Download PRE-AP BIOLOGY GENETICS PRACTICE PROBLEM DAY (2/5/15

PRE-AP BIOLOGY GENETICS PRACTICE PROBLEM DAY (2/5/15)
YOU MUST SHOW THE PUNNETT SQUARES FOR ALL QUESTIONS!!!!
USE YOUR OWN PAPER!!
Monohybrid:
1. In corn, normal kernels are dominant to waxy kernels. If you crossed a waxy kernel plant to a
heterozygous normal plant what type of seeds would be produced? Include all possible genotypes
and phenotypes.
2. Two short haired guinea pigs are mated several times. Out of 100 offspring, 25 of them have long
hair. What are the probable genotypes of the parents? Show the cross to prove it!
3. In pea plants, purple flowers are dominant to white flowers. A white flowered plant is crossed
with a plant that is heterozygous for the trait. What percentage of the offspring will have purple
flowers?
a. If out of 100 offspring 74 are purple flowered and 26 are white, what were the probable
genotypes AND phenotypes of the parents?
b. What are the parental genotypes needed to produce 100% white flowers?
Dihybrid:
4. Yellow fruit and dwarf vines are recessive traits in tomatoes. Red fruit and tall vines are dominant.
Complete a punnett square and answer the questions for a completely dominant red and tall plant
crossed with a heterozygous red and dwarf plant. (You chose the letters you want to use)
a. What percent of the offspring will be totally heterozygous?
b. What is the phenotype ratio?
c. What percent of the offspring will have yellow fruit and dwarf vines?
5. In humans, polydactylism (having an extra finger on each hand) is dominant to the typical 5-finger
arrangement. Tongue rolling is dominant to not being able to roll one’s tongue. A man who is
homozygous for 5-fingers and who cannot roll their tongue has children with a woman who is
heterozygous for polydactylism and tongue rolling. Draw a Punnett square that represents the
cross. What is the probability the couple will produce a polydactyl baby who cannot roll their
tongue?
Incomplete Dominance:
6. In radishes, the gene that controls color exhibits incomplete dominance. Pure-breeding red
radishes crossed with pure-breeding white radishes make purple radishes. What are the genotypic
and phenotypic ratios when you cross a purple radish with a white radish?
7. In Andalusian fowls, black individuals (B) and white individuals (W) are homozygous.
a. A homozygous black bird is crossed with a homozygous white bird. The offspring are all
bluish-gray. Show the cross as well as the genotypes and phenotypes of the parents and
offspring.
b. What are the genotypic and phenotypic ratios if a black individual is crossed with a bluishgray individual? Show the Punnett Square.
c. If two bluish-gray individuals were crossed, what would be the ratios for both phenotype
and genotype of the offspring? Show the Punnett Square.
Codominance:
8. In shorthorn cattle, when a red bull (RR) is crossed with a white cow (WW), all the offspring are
roan—a spotted, red and white or milky red color.
a. What offspring are expected from mating a roan bull and a roan cow? Show the Punnett
Square.
b. What phenotypes would you expect from a cross between a red bull and a white cow?
Show the Punnett Square.
c. If a roan bull were crossed with a red cow, what would be the possible phenotypes of their
offspring? Show the Punnett Square.
9. Crossing a black cat with a tan cat produces a tabby cat (combination of black and tan).
a. Cross a tan cat with a tabby cat, what are the phenotypes of the offspring?
b. If you wanted all tabby cats, what color cats would you want to breed?
10. A wealthy elderly couple dies together in an accident. A man comes forward, claiming that he is
their long lost son and is entitled to their fortune. The couple were of blood types AB and O. The
man has type O blood. Could he be the heir to the fortune? Show why or why not.