1. Genetic Patterns in Tribbles
#1 a) Red
b) black
c) pheno 3:1 red to black
geno 1:2:1 RR Rr rr
P1 RR x rr
F1 Rr
Rr x Rr
F2 RR Rr
Rr rr

2. Tribbles #2 A. Codominance both blue & yellow hairs HB and HY
HB HY x HB HB
green blue
HB HY
HB HB HB HB HY
ratios
Pheno: 50% blue hair
50% green (both)
1:1
Geno: 50% HB HB
50% HB HY

3. #3 a) Red, Blue and Yellow HR HB HY b) black and white hb hw
c) black is recessive to red, blue, & yellow, but black is dominant to white

4. #4 A) spotted and blue hair B) solid and black hair
C) T (spots) t (solid)
HB hb
D) To get a 9:3:3:1 ratio that is a normal dihybrid heterozygous cross:
TtHBhb x TtHBhb
THB Thb tHB thb
THB
Thb
tHB
thb

5. #5 A) spotted and red hair B) solid and white hair
C) white spots will not show on a white background (they blend in, but the spotted genes will still be there!)

6. #6 A) gene D seems to control how much pigment is made
B) There is a blending of color amounts, therefore this is incomplete dominance
C) no pigment is made therefore they are white
D) hwhw dd hwhw TT or tt
white hair no pigment white hair & spots/solid

7. #7 A) HB HR DD x HY HR dd B) HY HR Dd
purple with incomplete pigment production

8. #8
A) must be sex-linked if only males have the trait (or a majority of males have trait)
B) HB HB XnY x HB HB XNXn

9. #9 Genes in Tribbles chart
TRAIT
Dominant Allele
Recessive Allele
Coat Color
Blue HB
Red HR
Yellow HY
Black hb
White hw
Coat Pattern
Normal XN
Plaid Xn
Pigment
Production
Normal D
No pigment d
Spots
Spots T
Solid t

10. Additional Practice
This is on my website under links also!!
Go there for practice.