Download Probability of Traits in a Population

Probability of Traits in a Population
Name _________________
Date _________
Background Vocabulary

Purebred
Hybrid



or Homozygous : - the same genes for a trait - ex; BB, bb
or Heterozygous : -
Genotype -
differnet genes for a trait - ex: Bb, Ww
What the allele or gene is; ex.. BB or Bb.
Phenotype - What the traits “physically” looks like. Brown Eyes , Tall
Frequency : Number of individuals with a certain trait in a population.
Dominant Trait : A trait that masks another trait.
Recessive Trait : A trait that is suppressed by a dominant trait.
Problem:
What are some observable inherited traits in humans? What is the relationship
between frequency of a trait in a population and whether the trait is dominant or
recessive?
Make a hypothesis;
Make a hypothesis on the frequency of traits. Choose one of the hypotheses below.(you
can never really prove something true, but you can prove it false)
1- There are more dominant traits expressed in SMS students.
or
2- There are more recessive traits expressed in SMS students.
Hypothesis:____________________________________________________
_____________________________________________________________
Procedure
In this investigation you will conduct a survey of observable traits in humans (the
population tested will be your class).
1- Conduct the survey and record results.
2- Graph your results and calculate the frequency of each trait in a population.
Mr. Mullany
1
Probability of Traits in a Population
Observable Human Traits
Hair Line
Widow’s peak (W)
or
Straight across (w )
Earlobe
attached ( e )
or unattached ( E )
Eyes
Brown/Hazel ( B )
Mr. Mullany
or Blue/Green ( b )
Tongue
Roller ( R )
or
Non - roller ( r )
Thumb
Straight Thumb ( t )
or
Hitchhiker’s Thumb ( T )
Folded Hands
Left ( H )
or right ( h )
2
Probability of Traits in a Population
Observations
Record all results from the class survey.
Trait
Hairline
Dominant
Total Recessive
Window’s Peak
(W)
Tongue
Earlobe
Thumb
Eyes
Folded
Hands
Total
Straight Across
Hairline
Roller
(R)
Unattached
(E)
(w)
Non-roller
(r)
Attached
(e)
Hitchhiker’s Thumb
Straight Thumb
(T)
Brown/ Hazel
(B)
Left thumb over
right
(H)
(t)
Blue/Green
(b)
Right thumb
over left
(h)
Total Number of Students in Survey _________
1- Graph your observations on a piece of graph paper (attach graph paper to the lab and
use the format below). This is just an example. You have to graph your data as a double
bar graph on graph paper.
Graph
Dominant and Recessive Traits in SMS
Number of Students
20
15
10
5
0
Tongue Rolling
Dimples
Ear Lobes
eye Color
Traits
Dominant
Mr. Mullany
Recessive
3
Probability of Traits in a Population
Thought Questions
1- How many dominant traits tested in this lab do you have?
2- According to your chart, do most students in SMS have dominant or recessive traits?
(use the data from your class survey)
3-Which recessive traits are more common than dominant traits?
4- If you have brown eyes how many genotypes could you write for that dominant trait?
Explain?
5- If you have blue eyes, how many genotypes could you write for that recessive trait?
Explain?
Mr. Mullany
4
Probability of Traits in a Population
Conclusions
1- Generalize:
According to your results are the dominant traits the most common in a population or
are recessive traits more common? You are supporting or rejecting your hypothesis.
Explain your answer using the data to support it.
2- Infer: Write a possible genotype for yourself using all your traits.
(Remember if you have brown eyes your genotype for eyes can be BB or Bb. But if you
have blue eyes it can only be bb. )
My Genotype
Trait
Hairline (W)
Tongue Roller (R)
Ear Lobe (E)
Thumb (T)
Eyes (B)
Folded Hands (H)
Mr. Mullany
Genotype
5