Lab: Dominant and Recessive Traits
Name ______________________
Directions: Check off in the table below whether you inherited the dominant (D) or recessive (R) gene for the following genetic traits.
1. Tongue rolling: The ability to roll the tongue outside the mouth is due to a dominant trait.
2. Eye color: Although eye color is quite complex, assume that blue or gray eyes is the recessive trait and that brown, hazel, or other eye color
is an expression of the dominant gene.
3. Ear lobes: Most people have ear lobes that hang free at the bottom of the ear. Those people that have attached
ear lobes have the recessive trait.
4. Dimples: The presence of dimple(s) on the facial cheeks or on the chin is an expression of a dominant gene.
5. Widow’s peak: If the hair line drops into a point in the center of the forehead, this is an expression of a dominant gene. A continuous
hairline is the recessive expression.
6. Index/fourth finger: Place the hand, fingers together on your desk and see whether the index finger is shorter or longer than the ring (4th
finger). A shorter index finger is an example of dominant trait in males and recessive in females.
7. Interlocking fingers: Clasp your hands together with your fingers interlocked. A dominant gene is probably present if your left thumb is on top
of your right. If your right thumb is on top, then you have the recessive gene.
8. Curly hair: Curly hair is an expression of a dominant gene.
9. Bent little finger: A dominant gene causes the last joint of the little finger to bend inward, toward the fourth finger.
10. Long eye lashes: Long eye lashes indicate that a dominant gene is being expressed.
11. Straight thumb: While your hand is extended (like you’re going to shake someone’s hand), see whether your thumb is straight or curves
back towards your wrist. If your thumb is bent, it is known as a “hitchhiker’s thumb” and is a recessive trait.
12. Freckles: Freckles on the face indicate a dominant gene is expressed.
13. Hair on middle finger: Hair on the middle fingers, between the two joints, shows a dominant gene expression.
Total # of students in your class __________
TRAITS
DOM.
REC.
# OF
STUDENTS
SHOWING
DOMINANT
# OF
STUDENTS
SHOWING
RECESSIVE
% SHOWING
DOMINANT
TRAIT
% SHOWING
RECESSIVE
TRAIT
1.Tongue Rolling
2.Eye color
3.Ear lobes
4.Dimples
5.Window’s peek
6.Index/fourth finger
7.Interlocking fingers
8.Curly hair
9.Bent finger
10.Eye lashes
11.Straight thumb
12. Freckles
13. Hair on fingers
Conclusion:
% showing trait =
1. Determine the percentage of students who demonstrate each trait.
#students who have trait
X 100
Total number of students in class
2. Which dominant trait is most common in your class? ______________________________________________________________
3. Which recessive trait is most common in your class? ______________________________________________________________