Dominant and Recessive Traits
Name: ________________________________
Laboratory Investigation
Problem: What are the phenotypes of some dominate and recessive human traits?
Materials: Paper and Pencil
Procedure:
1. Complete the data table below
2. Count the number of students in your class who have each of the traits listed in the table. Record the number
with the dominant trait in column 3 and the number with the recessive trait in column 4.
3. Determine the percentage of students who demonstrate each trait as follows: Divide the number of students
who have the trait by the total number of students in your class and multiply by 100. Record your percentages
for dominant traits in column 5 and your percentages for recessive traits in column 6.
Data Table
Dominant
Traits
Recessive
1
Round Face
Square Face
2
No Cleft Chin
Cleft Chin Present
3
Curly Hair
Straight Hair
4
Widow’s Peak
Straight Hairline
5
Almond Shaped
Eyes
Round Shaped
Eyes
6
Straight Eyes
Slanted Eyes
7
Long Eyelashes
Short Eyelashes
8
Freckles Present
Freckles Absent
9
Dimples present
Dimples Absent
10 Free Ear Lobes
Attached Ear
Lobes
11 Dark Hair
Light Hair
Number of
Students
Demonstrating
Dominant Trait
Number of
Students
Demonstrating
Recessive Trait
Percentage
Demonstrating
Dominant Trait
Percentage
Demonstrating
Recessive Trait
12 Tongue Roller
Nonroller
13 Second toe longer Second toe shorter
than big toe
than big toe
14 Hair on middle
digit
No hair on middle
digit
15 Hitch Hiker’s
thumb
Straight thumb
16 High Convex Nose
Ridge
Flat Top Nose
Observations:
1. Which trait is most common in your class? Which is lest common?
2. Do any students have traits that are intermediate between the dominant and recessive traits? If, so, how many?
Describe the intermediate traits.
Analysis and Conclusions:
1. Do dominant traits occur more often than recessive traits? Explain.
2. Predict how your observations might be different if you were to observe four other classes of students.
3. State a hypothesis to explain why some students have traits that are intermediate.
Trait
Shape of
Face
Dominant
Recessive
Cleft in
Chin
Present
Absent
Widow’s
Peak
Absent
Present
Shape of
Eyes
Position
of Eyes
Straight
Slant
Dimples
Present
Absent
Ear
Lobes
Free
Attached
Tongue
Roll
Roller
Nonroller
Second
Toe
Longer than big toe
Middle
Digit
Hair
Thumb
Nose
Shorter than big toe