Name: _______________________________ Date: ___________________ Period: _______
Observing Human Traits Lab
Background: Physical traits are observable characteristics that are determined by genes.
Genes are specific segments of DNA located on chromosomes that code for a particular trait.
Most genes have two or more variations called alleles. Some alleles are dominant over others,
and dominant alleles will be expressed (an organism’s phenotype or physical appearance)
over recessive alleles. Recessive alleles may be present in an organism but expression will be
masked in the presence of a dominant allele for the same gene. Recessive traits will only be
expressed when there are two recessive alleles present in the genotype (the “code”).
Keep in mind that it’s not always quite this simple. There are other factors that can affect trait
expression, and most traits have several genes that influence expression. This lab is a basic
introduction to dominant and recessive traits. Let’s get started!
Directions: Circle the phenotype you have for each of the following human traits.
Personal Traits Inventory
Trait
Handedness
Phenotype
Right handed
Left handed
Unattached
Attached
Tongue rolling
Yes
No
Tongue folding
Yes
No
Cheek dimples
Yes
No
Freckles
Yes
No
Cleft chin
Smooth chin
Hairline shape
Widow’s peak
Straight hairline
Bent little finger
Yes
No
Mid-digital hair
Yes
No
Eye dominance
Right-eye dominant
Left-eye dominant
Double jointed fingers
Yes
No
Hitchhiker’s thumb
Yes
No
Right thumb on top
Left thumb on top
Right arm on top
Left arm on top
Yes
No
Earlobes
Chin
Hand clasping
Arm folding
Long second toe
©Tamra Young
Name: _______________________________ Date: ___________________ Period: _______
Observing Human Traits Lab
Background: Physical traits are observable characteristics and are determined by genes.
Some human traits include dimples, tongue rolling, and earlobes. There are two types of genes
for each trait: dominant and recessive. For example, earlobes can either be unattached
(dominant) or attached (recessive). If present, the dominant gene will always be expressed
(the physical appearance of the individual) over the recessive gene. The recessive gene will
only be expressed in the absence of the dominant gene. Keep in mind that it’s not always quite
this simple. There are other factors that affect trait expression that will not be covered in class.
This lab is a basic introduction to dominant and recessive traits. Let’s get started!
Directions: Circle the expression below you have for each of the following human traits.
Personal Traits Inventory
Trait
Handedness
Expression
Right handed
Left handed
Unattached
Attached
Tongue rolling
Yes
No
Tongue folding
Yes
No
Cheek dimples
Yes
No
Freckles
Yes
No
Cleft chin
Smooth chin
Hairline shape
Widow’s peak
Straight hairline
Bent little finger
Yes
No
Mid-digital hair
Yes
No
Eye dominance
Right-eye dominant
Left-eye dominant
Double jointed fingers
Yes
No
Hitchhiker’s thumb
Yes
No
Right thumb on top
Left thumb on top
Right arm on top
Left arm on top
Yes
No
Earlobes
Chin
Hand clasping
Arm folding
Long second toe
©Tamra Young
Directions: Record the expressions for you and 19 classmates. Find the total and ratio of each.
Classroom Traits Inventory
Student Name
Right/
left
handed
Attach/
unattach
earlobes
Double
jointed
fingers
Roll
tongue
Hitchhiker’s
thumb
Bent
little
finger
Widow’s
peak
Cleft/
smooth
chin
Right/
left eye
dominant
R/L
A/U
Y/N
Y/N
Y/N
Y/N
Y/N
C/S
R/L
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Total
Ratio
©Tamra Young
Observing Human Traits Lab
By: Tamra Young
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