Download Working with a partner, observe which form you have for each trait in

Name________________Period _________
Observing Human Traits
CPO 11A
Traits are physical characteristics you inherit from your parents. In this investigation, you will take an inventory
of your observable traits and compare these to the observable traits of your classmates.
Working with a partner,
observe which form you
have for each trait in the
table. Circle your form
of each trait in Table 1
(Note: for the final trait,
your teacher will give
you a piece of PTC paper
to taste).
Table 1 –Individual Data (circle the form you have for each trait)
Trait
Earlobe
Dimples
Chin
Hairline
Finger Hair
Thumb
PTC tasting
Form 1
Free
Present
Cleft
Widow’s Peak
Present
Straight thumb
Can taste
Form 2
Attached
Absent
No cleft
Straight
Absent
Hitchhiker’s thumb
Cannot taste
Stop and think
1. For earlobes only, how many students in you class do you think will share the same form (free or attached)
as you? Explain your reasoning.
How many students?
Explanation:
2. Do you think any of your classmates will have the same form of all traits as you? Make a prediction about
how many of your classmates will have the same form of all 7 traits as you. Explain your reasoning.
How many students?
Explanation:
Your teacher will display results for the whole class. Enter your results in Table 2 and then use
the data to calculate the frequency of each form of the trait for your class. Use this formula:
(# of students with form of trait ÷ Total number of students in class) x 100
Table 2 - Class data
Trait
Number of
students with
Form 1
Frequency of
students with
Form 1
Number of
students with
Form 2
Frequency of
students with
Form 2
Earlobe
Dimples
Chin
Hairline
Finger hair
Thumb
PTC tasting
Analysis:
1. For each trait, which form was most
common. Form 1 or 2? Answer using
the table at the right.
2. Why do you think one form is more
common than the other?
Trait
Which form was most
common?
Earlobe
Dimples
Chin
Hairline
Finger hair
Thumb
PTC tasting
3. Do you think you classroom population is typical of a larger population such as your
entire school or community? Explain your answer. Is our classroom typical?
Explanation:
Traits are controlled by factors called genes. For each trait listed in table 1, you get one gene
from your mother and one gene from your father. For many traits, there is a dominant form
and a recessive form. The dominant gene masks the effect of the recessive gene for the trait.
Looking back at the data you collected today, which form of each trait appears to be
dominant?