Class Trait Lab
Background: The passing of traits from one generation to the next is called
inheritance or heredity. Gregor Mendel was an Austrian monk and plant breeder
that studied the methods and the mathematics of inheritance in pea plants. From his
work came the study of genetics, which is the science of heredity. Mendel noticed
that certain specific traits in pea plants were passed on generation after generation. In
order to understand how these traits were passed on, he performed many years of
experiments. Mendel is known as the father of genetics.
Purpose: Survey your classmates to find out which versions of certain inherited characteristics
(or traits) are more common and which are less common.
Procedure: To begin, use your book to define the two terms below. Record your definitions
below (2 pts. Each)
1. Define TRAIT.
2. Define ALLELE.
3. Attached is a table of some genetic traits students in our class may have. We will use
these traits for our survey today. As you survey your fellow students, record the data in
the chart attached. To identify what each trait looks like, pictures of each trait will be
shown on the overhead screen.
4. Once the data for the class has been collected, calculate the percentages of each trait
(dominant or recessive). Fill in the numbers on your data table. (Data Table= 15 pts.)
{Percent (%) = number of students with the trait / total number of students surveyed X 100.}
{For example: 15 students with the trait / 25 students surveyed X 100 = 60%}
5. Once the data tables have been filled out, use the results from the % dominant and %
recessive columns to construct a double bar graph of your findings. (Graph paper is
attached) The X axis will be the genetic trait (phenotype) and the Y axis will be the
percentage of classmates with the trait.
6. Remember graphs must have a relevant title, properly labeled axes, and a key.
7. When graphing, use as much of the graph paper as possible. This means that the graph
should not be on one corner of the paper. It should cover most, if not all, of the graph
paper. (Graph= 15pts.)
Name ________________________________
Class Traits Lab Answer Sheet
The names of the traits are listed below in the data collection table. Mark your data in the
appropriate column based on presence or absence of each observable trait. Indicate the possible
genotypes of each phenotype in the same boxes (eg. HH, Hh or hh). Record the class numbers
for presence or absence of each trait. Finally, calculate the percentage of students that show the
trait surveyed. When all data has been processed and graphed, answer the conclusion questions
that follow.
Trait
Mark if Present/
Mark if Absent/
Class # dominant
Class # Recessive
(List possible
genotypes)
Hitchhikers Thumb
(H, h)
Unattached
Earlobes (E, e)
Widow's Peak
(W, w)
Roll Tongue
(T, t)
Right Handed
(R, r)
Mid Digital Hair
(M, m)
Freckles (F, f)
Dimples (D, d)
Cleft Chin (C, c)
Clasp hands left
over right?
(H, h)
Six fingers on one
hand (S, s)
Pinkie Fingers
bent (P, p)
Longer Big Toe
(B, b)
Taste PTC (T, t)
(List possible
genotypes)
Total
Class %
Class %
People
dominant
recessive
Analysis Questions: (2 pts. Each)
1.
What traits were you dominant for? Were you in the majority for this class?
2.
What traits are you recessive for? Were you in the majority for this class?
3.
Is there a pattern in the traits present in the classroom population? If so, describe.
4.
What factors would account for the similarities or differences in our classroom
population?
5.
Why would scientists want to know the percentages of traits in a population?
6.
Are dominant traits always the most prevalent in a population? Explain.
7.
Explain the benefits of having different traits among humans.
8.
What might happen if every human was genetically identical?