1. SC.912.L.16.1
Use Mendel’s laws of segregation and independent assortment to analyze patterns of inheritance.
Clarifications
Students will use Mendel’s laws of segregation and independent assortment to analyze patterns of inheritance.
Students will identify, analyze, and/or predict inheritance patterns caused by various modes of inheritance.
Content Limits
Items referring to general dominant and recessive traits may address but will not assess the P and generations. F1
Items addressing dihybrid crosses or patterns that include codominance, incomplete dominance, multiple alleles, sex-linkage, or polygenic inheritance may assess the P and generations. F1
Stimulus Attributes
Inheritance outcomes may be expressed in percent, ratios, or fractions.
Scenarios may refer to codominance or incomplete dominance but not both codominance and incomplete dominance.
Punnett squares may be used to predict outcomes of a cross.
Response Attribute
Options may include codominance or incomplete dominance but not both.
ESSENTIAL QUESTION: How do genes influence the variety of organisms that exist?

2. Dihybrid Cross
Inheritance of TWO traits from parents.

3. Law of Independent Assortment
Determining all possible allele combinations in gametes from each parent.
F.O.I.L
Directions
Genotype
Gametes F
First – Combine the first letters of each trait with each other.
PpGg PG O
Outer – Combine the outside letters of each trait with each other. Pg I
Inner – Combine the inside letters of each trait with each other. pG L
Last – Combine the last letters of each trait with each other. pg

4. Law of Independent Assortment

5. Practice problem
Parents are both heterozygous tall pea plants and round peas.
P X
T t
R r
T t R r
*Since there are two or more traits the law of independent assortment applies We Must FOIL
F O I L
F O I L
P1 ____ ____ ____ ____ X ____ ____ ____ ____
T R
T r
t R
t r
T R
T r
t R
t r

6. Complete Dominance Dihybrid
P1 _T R_ _T r_ _t R_ _t r_ X _T R_ _T r_ _t R_ _t r_
Offspring Genotype
T R
T r
t R
t r
1 TTRR : 2 TTRr : 2 TtRR
4 TtRr : 1 TTrr : 2 Ttrr
1 ttRR : 2 ttRr : 1 ttrr
T R
TTRR
TTRr
TtRR
TtRr
T r
TTRr
TTrr
TtRr
Ttrr
Offspring Phenotype
9:3:3:1
Tall Round = 9
Tall wrinkled = 3
Short round = 3
Short wrinkled = 1
t R
TtRR
TtRr
t tRR
t tRr
TtRr
Ttrr
t t Rr
ttrr
t r

7. They Do Wisconsin Fast Plant Lab
A cross between the F2 generation have been set up for you.
Students will analyze the phenotypic ratios of the fast plants.
How many separate traits are observed?
What are the possible genotypes and phenotypes of the parents of this cross?
What are the genotypes and phenotypes of the cross?