Science 10 BLOCK _______________
Name_________________________
Observable Human Traits Lab
Curricular Competencies
Make observations aimed at
identifying their own
questions, including
increasingly complex ones,
about the natural world
Seek and analyze patterns,
trends, and connections in
data
Use knowledge of scientific
concepts to draw conclusions
that are consistent with
evidence
Transfer and apply learning
to new situations
What you need to do to show
this skill
Marks
- Make observations about
the visible traits in yourself
and others
____/5
- Calculate the percentages of
students in class with each
trait
- Analyze data and make
connections to biology
(genetics and inheritance)
concepts
____/6
- Answer questions 1-3
- Answer follow-up questions ____/6
4-5
OVERALL _______/17
Name____________________
Observable Human Traits Lab
In the 1800s, Gregor Mendel performed breeding experiments on pea plants. His careful
observations were the basis of modern understanding of genetics and inheritance.
Certain traits in humans have two different variants (alleles). One allele is dominant and
the other is recessive. A person can have three possible combinations of alleles;
homozygous dominant, heterozygous, or homozygous recessive.
Purpose of this lab:
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The following table has explanations for some easily observable traits in humans. Each
has at least two alleles.
1.
2.
3.
4.
Within your group, record how many people either show the trait or not.
When done, add your group’s data to the class data table.
Record the class data into Table 1 on your lab
Calculate the percentage of students in the class who show and do not show each
trait
percent = number with the trait ÷ total number of students
5. Use this data to answer the follow-up questions
Number of students in the class:________________
Table 1. Results of observable human characteristics.
Trait
Number of people
with this trait
% with
trait
Number of people
without this trait
% without
trait
Attached earlobe
Tongue rolling
Dimples
Right handed
Freckles
Curly hair
Widow’s peak
Brown eyes
Cleft chin
Taste bitterness
Follow-up Lab Questions:
1. Did any of the class results suggest that one trait definitely had a dominant allele? If so,
which ones? How do you know? (2)
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2. Did any traits show an equal percentage of students with each allele? What do you think
this means? (2)
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3. Is there a trait from this lab that you are sure you have either the dominant or recessive
allele? Which one?______________________________________________________
Based on this, what can you assume about your biological parents' alleles for this trait?
Explain your answer thoroughly. (2)
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4. Explain, in detail, why you look different than your biological parents. And why do you
look different than your siblings/other family members? (2)
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5. Create 2 punnett squares for a cross between a person who can roll their tongue and a
person who cannot. (2)
a. Cross a homozygous dominant TT parent with a homozygous recessive tt parent.
b. Cross a heterozygous Tt parent with a homozygous recessive tt parent.
c. If those two people had four children, how would you know if the parent who
could roll their tongue was homozygous or heterozygous? (2)
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