Biology 1010:
Laboratory Six:
Genetic Crosses
Direction: There
is no simulation for this report. Completion of this lab report will be based
on reading Chapter 7 and using the word file entitled Lab 6 Handout: Sample
Genetic Crosses posted on Launchpad as a guide.
Table 1: Below is
a list of the phenotypes used in this lab.
These are all single gene traits that show complete dominance. Use this information to set up and analyze
your crosses.
Trait Dominant phenotype Recessive Phenotype
Flower color Purple flowers White flowers
Plant Height Tall plants Short Plants
Seed Shape Smooth seeds Wrinkled seeds
Seed Color Yellow seeds Green seeds
Part One: Symbols
and definitions:
1. Short answer questions:
a. What is a gene? (0.25pts)
A gene is a unit
of heredity that is passed on from a parent to its offspring and is used to
determine the characteristics of the offspring.
b. What is an allele? Give an example of 2 alleles of a human
gene. (0.25 pts)
An allele is a
trait of the gene. Individuals have two copies of each gene inherent from both parents;
examples of this could include things like the offspring’s blood type, hair or
eye color, etc.
c. What is the difference between an
organism that is a homozygote and one that is a heterozygote? (0.25 pts)
A homozygote is
an individual organism with two copies of the same allele that determines a
specific trait, while a heterozygote has a copy of two different alleles for
the same trait.
d. What is the difference between an
organism’s genotype and its phenotype? (0.25 pts)
An organism’s
phenotype would be the outward appearance of that individual, where the
genotype would be the organism’s genetic composition.
2. For each trait in the table below,
indicate ALL OF THE GENOTYPES that are possible. Use the first letter of the dominant trait to
indicate the trait. (2pts)
Trait Dominant genotype(s) Recessive genotype(s)
Flower color Purple = PP Pp pP White = pp
Plant Height Tall = TT Tt tT Short = tt
Seed Shape Smooth = SS Ss sS Wrinkled = ss
Seed Color Yellow = YY Yy yY Green= yy
Part Two: Genetic
Crosses
1. Pick three of the crosses to
complete using any 3 of the last 4 digits of your CUNYFirst Empl ID. If there are repeats, pick random numbers, so
you are doing 3 different crosses.
2. Highlight the numbers of the crosses
you are doing in column 1 below. You
must pick 3 different crosses.
Cross Number Male parent traits Female parent traits
0 Heterozygous for flower color
Heterozygous for
height Homozygous dominant
for flower color
Heterozygous for
height
1 Heterozygous for flower color
Homozygous
dominant for height Heterozygous
for flower color
Homozygous
dominant for height
2 Heterozygous for flower color
Heterozygous for
seed color Heterozygous for flower
color
Heterozygous for
seed color
3 Homozygous recessive for flower
color
Heterozygous for
seed color Homozygous dominant for
flower color
Heterozygous for
seed color
4 Homozygous recessive for seed
shape
Homozygous
recessive for height Heterozygous
for seed shape
Heterozygous for
height
5 Heterozygous for seed shape
Heterozygous for
height Heterozygous for seed
shape
Homozygous
recessive for height
6 Homozygous dominant for flower
color
Homozygous
recessive for seed shape Homozygous
recessive for flower color
Homozygous
dominant for seed shape
7 Heterozygous for flower color
Homozygous
recessive for seed shape Heterozygous for
flower color
Homozygous
recessive for seed shape
8 Heterozygous for seed shape
Heterozygous for
seed color Homozygous recessive for
seed shape
Homozygous
dominant for seed color
9 Heterozygous for seed shape
Homozygous
recessive for seed color Homozygous
recessive for seed shape
Homozygous
recessive for seed color
1. Now you can use the charts and
Punnett squares on each of the following pages to complete your crosses. You can use the Lab 6 Handout: Sample Genetic
Cross posted on LaunchPad directly below the lab for a guide in doing these
crosses
Cross 1: Please write the number of the cross you are
performing: ______________
Then fill in the
genotype and phenotype for each parent below.
Use the sample of a genetic cross posted on LaunchPad directly below the
lab for a guide.
Sex Genotype Phenotype
Male
Female
Step 1: Determine the different gamete combinations
that each parent can contribute to the offspring. Check the hint from the sample problem when
you are doing this.
Sex Gamete 1 Gamete 2 Gamete
3 Gamete 4
Male
Female
Step 2: Fill in
the Punnett Square below
Male gametes place across
?
Female Gametes:
Place below: ?
Step 3: Find the
Phenotype of each of the 16 combinations in your Punnett Square page.
Phenotype you’ve
found in offspring Number of offspring
with this phenotype
Cross 2: Please write the number of the cross you are
performing: ______________
Then fill in the
genotype and phenotype for each parent below.
Sex Genotype Phenotype
Male
Female
Step 1: Determine the different gamete combinations
that each parent can contribute to the offspring.
Sex Gamete 1 Gamete 2 Gamete
3 Gamete 4
Male
Female
Step 2: Fill in
the Punnett Square below
Male gametes place across
?
Female Gametes:
Place below: ?
Step 3: Find the
Phenotype of each of the 16 combinations in your Punnett Square page.
Phenotype you’ve
found in offspring Number of offspring
with this phenotype
Cross 3: Please write the number of the cross you are
performing: ______________
Then fill in the
genotype and phenotype for each parent below.
Sex Genotype Phenotype
Male
Female
Step 1: Determine the different gamete combinations
that each parent can contribute to the offspring.
Sex Gamete 1 Gamete 2 Gamete
3 Gamete 4
Male
Female
Step 2: Fill in
the Punnett Square below
Male gametes place across
?
Female Gametes:
Place below: ?
Step 3: Find the
Phenotype of each of the 16 combinations in your Punnett Square page.
Phenotype you’ve
found in offspring Number of offspring
with this phenotype
Questions:
1. Are gametes haploid or diploid? What about the offspring, are they haploid or
diploid? (1pt)
2. Can two short and green seeded
parents produce offspring that are tall and have yellow seeds? Explain using a
Punnett square why you think this outcome is possible or not. (1 pt)
3. Can two purple flowered and yellow
seeded parents produce offspring that have white flowers and green seeds? Explain using a Punnett square why you think
this outcome is possible or not. (1 pt)
