Practice Genetic Problems II
Honors Biology
1.
In a certain species of tropical bird, the feathers on the head can either form a vertical crest or lay flat. When a truebreeding crested bird is mated with a flat-topped bird, the offspring are crested. What would be the genotypes of two birds
that produce offspring that are 50% crested, 50% flat-topped?
In order for this to work, you must cross a heterozygous crested (Cc) with a flat-topped bird
(cc).
c
c
C
Cc
Cc
c
cc
cc
In this same species of bird, the feathers on the wings can be either forked (F) or complete (f). What offspring would be
expected from a mating of complete wing-feathered, heterozygous crested bird with a true breeding forked wing-feather,
heterozygous crested bird?
complete wing, heterozygous crested x true breeding forked, heterozygous crested
ffCc
fC
fc
2.
x
FFCc
FC
Fc
FC
FFCc
FfCc
Fc
FFcc
Ffcc
IA
i
IB
IAIB
IBi
i
IAi
ii
Japanese 5 o’clocks are flowers with either red or white blossoms. If you cross a red and a white blossom, the offspring are
pink. If you cross two of these pink Japanese 5 o’clocks and they produces 214 offspring, what colors, and what quantities
would you expect?
RR’ x RR’ yields 53-54 red flowers (25% of 214), 107 pink flowers (50% of 214), and 53-54 white
flowers (25% of 214)
4.
fc
If parents with type A and type B blood have children, what blood types are possible?
If the parents are heterozygous (IAi and IBi), then they could have kids of all possible blood
types: O (ii), A (IAi), B (IBi), and AB (IAIB).
3.
Fc
R
R’
R
RR
RR’
R’
RR’
R’R’
In Drosophila melanogaster, the fruit fly, white eyes are a sex-linked recessive trait. After crossing a white-eyed male with a
red-eyed female, how many white eyed offspring would you expect?
None. A white eyed male (XwY) and a red eyed female (XX) cannot produce white-eyed
offspring.
Xw
Y
X
XXw
XY
X
XXw
XY
Xw
Y
When crossing a white eyed male with a carrier female, what offspring would you expect?
A white-eyed male (XwY) and a carrier female (XXw) would produce equal numbers of whiteeyed males, red-eyed males, white-eyed females, and red-eyed females.
w
X
XX
XY
Xw
XwXw
XwY