Another CIM Opportunity!
Investigation: Human Genes
Name:
Per:
Before you begin your investigation you will check your understanding of genotypes, phenotypes, alleles and the possible
combinations we find for a trait by filling out the following table:
Fill in the table below for each genetic trait.
Genetic Trait
Possible phenotypes
in population
Ability to roll
tongue
Type of earlobe
Type of thumb
Type of hairline
Freckles
Dimples
Your Phenotype
Alleles
Possible genotypes
in the population
Your possible
Genotype(s)
Part 1:Background for Examining the Frequency of Each Trait in the Population
Your CIM lab should begin with a Title, Question, and Hypothesis:
Title: Write a title below that is specific and includes detail about your investigation:
Question: Is the dominant trait in a population always more common than the recessive?
Hypothesis: Write your hypothesis below. Remember, a hypothesis should be in the ‘If…, then….’ format, and should state a
relationship between your two variables.
Now you need to write your Background Information:
Background Information should explain the terms and concepts that you need to know to understand your investigation. It should
also explain the reasoning that backs up your hypothesis. The Background Information should not contain the results of your
investigation. That information will be discussed in your conclusion.
You should answer the following questions in your Background Information:
What is a trait?
What is the difference between a phenotype and a genotype?
What are alleles and where do they come from?
What do we mean when we say a trait is dominant or recessive?
How will we look at frequencies in our population?
How do the above questions relate to your hypothesis?
Write notes or the rough draft for your Background Information below:
Part 2: Materials and Procedures
Materials: We will not have many materials for this lab but you should list any that you use:
Procedure: Conduct a survey of at least 40 people in your school or community to see what their phenotype is for each of the
following 3 traits:
1. Widow’s Peak
2. Ability to roll tongue
3. One other trait of your choice from page One.
Be sure that you give a detailed description of the steps you used to collect your data. You should describe the questions that you
asked, how you decided who to ask, any determinations you made about your populations, and difficulties that you encountered in the
procedure.
Write your procedure in steps. Include any drawings that illustrate what procedure you followed.
Part 3: Presenting the Data
Collecting Data:
YOU WILL NEED TO DESIGN A DATA TABLE ON ANOTHER SHEET OF PAPER THAT WILL
INCLUDE THE NAME OF EACH PERSON THAT YOU SURVEYED AND THE RESULTS OF THE
SURVEY.
FILL IN THIS DATA TABLE WHEN YOU HAVE COMPLETED YOUR SURVEY OF INDIVIDUALS:
Phenotype
Widow’s
Peak
No Widow’s Can Roll
Peak
Tongue
Cannot Roll
Tongue
Tally of
individuals
Total
number
Percentage calculations:
For each of the 3 traits you have collected data for (widow’s/no widow’s peak, rolling/not rolling tongue, and the trait of your
choice), calculate the percentage of individuals who show each phenotype.
Phenotype
Percentage of
individuals
with each trait
Widow’s Peak No Widow’s
Peak
Can Roll
Tongue
Cannot Roll
Tongue
Graph your data:
For each of the three traits you collected data for, create a bar graph to represent the data. You may put your graph in the space below
or on a separate piece of paper attached to this paper.
Part 3: Analysis and Conclusion
This is a key part of the investigation where many students lose points in their write-up.
You need to explain clearly:
What you found out in the investigation (refer to specific data!)
Whether it supports your hypothesis or not
Why does this happen?
What else might you discover about this subject and how would you design an investigation?
Analyze the data and draw conclusions by answering the following questions. USE THESE ANSWERS, AND THE QUESTIONS
ABOVE, TO HELP YOU WRITE YOUR CONCLUSION.
1. a) From the data table on page one: is a widow’s peak a dominant or recessive trait?
b) From the data you collected: Is widow’s peak or no widow’s peak the more common trait in the population?
2. a) From the data table on page one: is the ability to roll the tongue a dominant or recessive trait?
b) From the data you collected: is the ability to roll the tongue or the inability to roll the tongue the more common trait in the
population?
3. Fill in the blanks for the 3rd trait you surveyed.
a) From the data table on page one: Is ___________________________ a dominant or recessive trait?
b) From the data you collected: Is ___________________________ or ___________________________the more common
trait in the population?
4. Is your hypothesis supported? From the analysis of your data, does dominance correlate with frequency in the population (in
other words, is the dominant trait always the more common trait in the population)? Explain your answer using your
data.
5. Explain why this happens. This is a very important part of your conclusion!
6. Explain 2 ways in which this investigation could be improved or expanded upon to give more reliable data for the human
population.