Unit 6 Genetics Study Guide:
Use your Interactive Notebook to either highlight the the answer
in your interactive notebook (if you find the answer there) or write the answer in your interactive notebook. You
will be able to use your interactive notebook ONLY on the test next class.
Define:
Gene
Allele
Homozygous
Heterozygous
Genotype
Phenotype
Dominant
Recessive
Mendelian
Inheritance
Pea Plant Characteristics:
Characteristic
Dominant Allele
Recessive Allele
Flower Color
Purple (P)
White (p)
Seed Color
Yellow (Y)
Green (y)
Seed Shape
Smooth (S)
Wrinkled (s)
Pod Color
Green (G)
Yellow (g)
Use the above table to fill out the following tables:
For each genotype, indicate whether it is homozygous dominant, homozygous recessive or heterozygous.
PP
Yy
Ss
pp
gg
GG
For each genotype, indicate the phenotype.
PP
Yy
Ss
pp
gg
GG
For each phenotype indicate the possible genotype(s).
White flower
Green Pod
Smooth seeds
Green Seeds
Yellow seeds
Wrinkled seeds
Complete punnett squares for the following crosses:
1. A purple flower plant with the genotype of PP is crossed with a purple flower plant with the genotype Pp. This is an
example of simple Mendelian inheritance.
What is the probability of purple flower offspring? _____________
What is the probability of white flower offspring? ______________
What is the genotype ratio of the offspring? __________________
What is the phenotype ratio of the offspring? _________________
2. A heterozygous freckled person is crossed with a non freckled person. Assume this is simple
mendelian inheritance..
What is the probability of purple flower offspring? _____________
What is the probability of white flower offspring? ______________
What is the genotype ratio of the offspring? __________________
What is the phenotype ratio of the offspring? _________________
Non-Mendelian Inheritance:
Define and give an example of:
Incomplete Dominance
Codominance
Multiple Alleles
1.
How many alleles must be present in order for a par cular trait to show up in the offspring?
________________________
2.
Where does an offspring get its alleles? __________________
___________________________________________________
3.
If parents have two alleles for every trait, how do they pass only one of their alleles to their offspring?
________________
___________________________________________________
Give 3 examples of each of these things:
Dominant Allele
Recessive Allele
Genotype
Phenotype
Homozygous
dominant
Homozygous
Recessive
Heterozygous
Punnett Square Practice Problems: Use the format to solve the problems. Be
sure to EXPLAIN your answer in words!
Widow's Peak is a dominant trait, with straight hairline being the recessive form of hairline. Two people with
Widow's Peak Hairlines have 5 children. All have straight hairlines. How can this be? What is the chance that
each child would have a straight hairline? You can do a punnett square on paper to help you find your answer.
Write your answer in complete sentences.
Long eyelashes are a dominant trait. In what situation can two people with long eyelashes have a child with
short eyelashes? What is the chance of this happening?
In rabbits, the allele for black coat color (B) is dominant over the allele for brown coat color (b). Two black
rabbits are mated. They produce some offspring that are black and some that are brown. What could the
possible genotypes of the parents (there is more than one way this can happen).
Freckles are a dominant trait. What are the potential genotypes and phenotypes and their proportions if a
woman heterozygous for freckles who has children with a man with no freckles.
Manx cats have no tails. This is caused by a regulatory gene, which is dominant. N= no tail, n=tail. A second
pair of genes gives a cat L=long tails, l=shorter tails. What kind of tail will the following genotypes have?
Genotype
SSll
ssLL
Phenotype
Explain why
SsLl
ssLl