Name ____________________ Pd _____ Score
Purpose: 1. To be able to complete single and double trait crosses.
2. To be able to complete single and double trait crosses
for incomplete dominance.
3. To be able to complete crosses for sex-linked and
1. Legos 25-30 of at least 2 to 4 colors, of two different
Example Tall =T and = a red 8 dot Lego t=short and
a 4 dot red or 8 dot other color such as yellow.
2. Make a grid 4by 4 on a sheet of paper that is at least a
foot on each side.
3. Use Legos in place of the letters.
4. Crosses will be put on the board. Students will set up
the cross and the gametes on the paper to be checked
by the teacher.
5. Students will fill in the grid list genotype and phenotype
on lab data sheet.
6. Students will write out selected crosses on paper or
put them on the board to demonstrate their
1. Cross ______ : _______ genotype phenotype
1. How does independent assortment work to
effect genetic recombination.
2. Examine the genotypic and phenotypic ratios for the
single and double crosses with the dominant
and recessive traits. Compare these to Mendel's results.
a/ How do your results compare?
b/ Why do your think it turned out this way?
c/ How might this work in the real world of selective
3. Explain the results for the crosses with the incomplete
a/ Compare the genotype and phenotype ratios.
b/ What if Mendel had known about incomplete
4. Design an experiment to demonstrate a/ a dominant and
b/ a recessive mutation.
Note to the teachers:
Sex- linked crosses require that you have the students
designate one large Lego as the X chromosome and one short one
as the Y chromosome. When the X carries the trait you have the
students put a single or double dot Lego on the X to denote which
X carries the trait.