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Name: _______________________________
Date: ______________
Block: _______
C.P. Biology
Genetics Problems II
1. Spotted rabbits crossed with solid-colored rabbits produce all spotted offspring. When
the F1 rabbits were crossed they produced 32 spotted and 12 solid-colored offspring.
Which trait is dependent upon a dominant gene? ______________
How do you know? _____________________________________________________________
Perform a punnett square of the P1 generation and the F1 generation to prove the results
you just explained. Give both genotype and phenotype ratios.
Genotype ratio:
KEY:
Phenotype ratio:
2. In the above problem, how many of the F2 spotted rabbits would you expect to be
homozygous? __________ How many of the F2 solid-colored rabbits would you expect to be
homozygous? __________ Explain your reasoning and use your punnett square work to
prove your answer.
KEY:
3. In sheep, white-colored wool is due to a dominant gene and black to a recessive allele.
A white ewe crossed with a white ram produced a black lamb. If the same parents produce
another lamb, could it be white? __________ If so, what is the % chance of that happening?
_______________ List the genotypes of the ewe, ram, and black lamb. Include a punnett
square to prove your data.
Ewe: ____________ Ram: ____________ Lamb: ________
KEY:
4. In dogs, wire hair is a dominant trait while smooth hair is recessive. Two wire haired
dogs produce a litter of four wire-haired puppies. To determine if the male dog is pure for
wire hair or carries the gene for smooth hair, what should you do? ____________________
What type of female should he be crossed with? _________________ Use punnett squares to
prove your reasoning.
KEY:
5. In radishes, the shape of the bulb may be long, round, or oval. Crosses between a.) long
and oval produced 159 long and 156 oval; crosses between b.) long and round produced
576 oval; crosses between c.) oval and round produced 203 oval and 199 round; crosses
between d.) oval and oval produced 254 round, 493 oval, and 253 long. What type of
inheritance pattern is shown with this experiment? ___________________________________
Give the genotypes of each of the parents in crosses a-d.
KEY:
Parent
Genotypes:
6. In horses, black is dependent upon a dominant gene (B) and chestnut is the recessive
trait (b). Trotting gait (T) is dominant over pacing gate (t). Predict the phenotype ratios if
a homozygous black, heterozygous trotter horse is crossed with a heterozygous black,
heterozygous trotter horse. Show your results in a punnett square.
Key:
Phenotype ratio:
7. How many different kinds of gametes could be produced by a guinea pig with the
genotype bbLlRrSs?
8. Predict the results of a cross between a mom with blood type AB and a dad with blood
type B heterozygous. Show your results with a punnett square. Can they have a child with
type O blood? ________________
What type of inheritance pattern is this? ____________________
9. In humans, normal pigmentation (C) is dominant over albinism (c). A normal man
marries an albino woman. Their first child is an albino. What are the genotypes of these
three individuals? Dad: ____________ Mom: __________ Child: ___________ If these parents
have more children, what will be the probability that they will have more albino children?
____________ What is the probability that they will produce a normally-pigmented child?
___________ Show your results in a punnett square.
KEY:
10. An albino man marries a normally pigmented woman. They have 9 children who are all
normally pigmented. What would you surmise are the genotypes are of the
mom: ____________, dad: ____________, and children: ______________________________________?
Explain.
11. In cats, yellow fur is dominant (B) over black fur (b). The heterozygous condition (Bb)
results in a tortoise-shell pattern. The genes B and b are sex-linked on the X chromosome.
What kinds of offspring would be expected to result from the cross of a black male (XbY)
and a yellow female (XB XB)? ______________________________________________ Use a punnett
square to prove your results.
12. Using the information in problem 11, perform a cross between a black male and a
tortoise-shell female cat. What kinds of offspring, and in what ratios, would you expect to
see as a result of this mating? ____________________________________________________________ *
Prove your results in a punnett square.
13. Referencing information from problems 11 and 12, perform a cross between a yellow
male and a tortoise-shell female cat. If the female has a litter of four male kittens, what
color would they most likely be? _______________________________________________________ *
14. In mice, the following series of multiple alleles is known: Ay results in yellow fur. A_
results in gray fur. aa results in black fur. Ay Ay is a fatal condition. What kinds of
offspring, and in what ratios, will result from the following crosses:
Aya X Aa;
Ay a X aa;
Ay A X Ay A.
Give
Results:
15. In the P generation, a dog homozygous dominant for straight fur (FF) is crossed with a
dog homozygous recessive for curly fur (F’F’). The results of the F1 generation were 8
puppies with wavy fur. What type of inheritance pattern does this represent?
_________________________ If two dogs with curly fur mate and produce a litter of puppies,
what would you expect the phenotype ratios to be? ________________________________
Make a punnett square to support your results.
16. Hemophilia is a sex-linked genetic disorder that affects the body’s ability to clot blood
properly. If a man with hemophilia marries a normal female, what are the chances that any
of their children will have the disease? ______________ Will any males be affected?
__________________ Any females? _____________________ Now perform the same cross with
the female a carrier. How will the results change?
17. Imagine that there is a dominant gene that protects against sun-burning (T) and a
recessive gene that increases intolerance to the sun and causes sun-burning (t). If this trait
has a simple inheritance pattern, what is the probability that parents would have sunintolerant children if they are both heterozygous for the trait? ______________ What if the
inheritance pattern were incomplete dominance with the same parents. How would the
results change? _________________ And what if the traits were sex-linked, where dad is XtY
and mom is XT Xt? _____________________ Prove your answers using punnett squares.