Characteristics

Pre-lab discussion

Independent assortment v. linked Dichotomous v. continuous traits Polygenic traits correlation

Hypothesis (Write 3!)

Independent variable: a pair of traits Dependent variable: number of

classmates with traits Predict: Linked or not? One hypothesis for continuous traits, two

hypotheses for dichotomous traits.

DATA:

Record ALL of your data in write-upFor the pairs you choose to test,

record ALL class data.

Continuous traits:

Height: Weight: Arm Span:

Dichotomous traits

These will be analyzed with contingency tables:

yes

no

yes no

Tongue Rolling (T, t)

Attached Earlobes (E, e)

e E

PTC Taste (P, p)

Sex (X,Y)XX xy

Dimpled Cheeks (D, d)

Dimpled Chin (C, c)

Widow’s Peak (W, w)

Bent Little Finger (L, l)

Double-Jointed Thumb (J, j)

Middigital Hair (H, h)

Freckles (F, f)

Hitchhiker’s Thumb (G, g)

Webbed Toes (W, w)

Wooly Hair (R, r)

Analysis

Discuss scatterplot graph and the two contingency tables.

Questions

1. What are “polygenic” traits? Which traits in this lab arePolygenic?2. What are “dichotomous” traits?3. Dichotomous traits are controlled by single gene. Give four examples of these from the lab.4. What does it mean for two traits to be “linked”?5. According to your data, what other traits besides the onesyou hypothesized about, do you think might be “linked”?6. If you had to determine red hair and freckles, or blond hairblue eyes were linked, how would you do it?