Download (b).

GENETICS Practice
Chapter 3 & 4
G
g
G GG Gg
g Gg gg
The parents in this cross
Heterozygous
are _____________
Homozygous
Heterozygous
If G is dominant for green pods and g is recessive for
yellow pods, what percentage of the offspring will
have green pods? _______%
75
B b
B
b
The genotype of the
offspring in the blue box
is _______
bb
The offspring in the blue box is
homozygous
heterozygous
homozygous
In guinea pigs black fur (B) is dominant over
brown fur (b). The Punnett square for a cross
between a HETEROZYGOUS black guinea pig
and a PURE brown guinea pig would look like
B B
B b
B b
B b
B
b
b
B
b
b
b
B
This is the
Correct setup
Heterozygous = Bb
Pure brown = bb
homozygous
Another name for pure is _________________
What is X?
• The human body has 46 chromosomes.
• The chromosomes work in pairs, so there
are 23 pairs of chromosomes.
• 22 out of the 23 pairs are the same for men
and women.
What is Xy?
• The other two are the ones that determine
what gender you'll be.
– A woman has two X chromosomes (X is the
name of the chromosome) and a man has one X
and one Y chromosome.
• This means that when a man forms sperm, they can
either have an X chromosome or a Y chromosome,
while the female gametes can only have X
An organism has the genotype Xy.
What are the possible sperm it can produce?
______
______
X
y
THINK ABOUT IT:
If females have an XX genotype and can
only give X genes, which parent is the one
that determines whether the baby is a boy or
girl? Father ;
The mother always gives an X
If the father gives a y, it’s a boy.
If the father gives an X; it’s a girl.
Codominance
The meaning of the prefix "co-" is "together".
Cooperate = work together.
Coexist = exist together. Cohabitat = habitat together
• Alleles are neither dominant nor recessive .
• As a result both alleles are expressed in the
offspring.
Incomplete Dominance
• Both forms of the trait show in
a mixed form.
(end up with something in-between )
Example: A cross between a blue blahblah bird & a
white blahblah bird produces offspring that are
silver.
1) Notice that the offspring is showing a 3rd phenotype. The
parents each have one, and the offspring are different
from the parents.
2) Notice that the trait in the offspring is a blend (mixing) of
the parental traits.
SpongeBob loves growing flowers for his pal Sandy! Her
favorite flowers, Poofkins, are found in red,
blue, and purple. Use the information provided and your
knowledge of incomplete dominance to
complete each section below.
• 1. Write the correct genotype for each color if R
represents
a red gene and B represents a blue gene.
• Red - _____
RR Blue - ______
BB Purple - _____
RB
If you cross a homozygous RED flowered four o’clock
plant with a homozygous WHITE flowered plant,
ALL of the offspring produced have PINK flowers.
This type of inheritance in which the heterozygote (Rr)
shows a blending of traits is called __________.
A. Dominant/recessive inheritance
B. Co-dominance
C. Incomplete dominance
Incomplete dominance
R
r
r
Rr
Rr
r
rr
rr
What are the possible phenotypes of
their offspring?
(% and color)
Red throats (R) are
dominant over white (r)
throats in Goonie birds.
Make a cross between a
PURE RECESSIVE
and a
HETEROZYGOUS
Goonie bird.
50% red throats
50% white throats