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Genetics Unit - Test Review
This test will cover genetics, genetic disorders, and chromosomal disorders. First and foremost, study the
notes given in class! Second, look over the two quizzes on genetics. Review the worksheets covering
incomplete dominance (spongebob), codominance (blood typing), and sex-linked traits. Just because
something is not on the review guide does not mean that it will not be on the test.
1. Describe Mendel’s work. You should know what he worked with and what he discovered.
He worked with pea plants. Discovered patterns of inheritance, dominant
and recessive traits
2. Solve the following types of genetic problems:
1 trait crosses involving a dominant and a recessive gene.
(Tt X Tt)
T=Tall t=short
T
t
Genotypic Ratio= TT 25% :Tt 50% :tt 25%
T
TT
Tt
Phenotypic Ratio= Tall 75% : short 25%
t
Tt
tt
3. Fill in the missing Dihybrid genotypes: 2 trait crosses involving 2 dominant and 2 recessive genes.
(TtGg X TtGg) T=Tall t=Short
G=Green g=yellow
TG
Tg
tG
tg
TG TTGG
TTGg
TtGG
TtGg
Tg
TTGg
TTgg
TtGg
Ttgg
tG
TtGG
TtGg
ttGG
ttGg
tg
TtGg
Ttgg
ttGg
ttgg
4. 1 trait cross that is sex-linked. (in this case, pretend that the disorder is caused by a recessive allele)
(XHXh X XHY)
XH
Xh
XH
Y
XH XH XH Xh
XHY
Xh Y
Describe the possible offspring:
3 “normal” 1 with disorder
1 normal male, 1 male w/ disorder, 1 normal female, 1 carrier female
5. A cross involving 2 genes that are codominant.
Cross a Heterozygous A blood type women with a Heterozygous B blood type man.
A
O
List all of the possible genotypes: AB, AO, BO, OO
B
AB
BO
List all of the possible phenotypes:
O
AO
OO
Type AB Blood, Type A Blood,
Type B Blood, Type O Blood
6. Pedigrees: Make sure you
put in generation #’s
Which individuals are:
Male: I- 1, 3; II- 2, 4, 6; III-1
I
Affected: III- 1
3
4
II
1
Female: I- 2, 4; II- 1,3,5; III-2
Carriers: I- 2,4; II- 3
2
1
2
3
4
5
6
III
1
2
7. What is a karyotype and identify some of the problems that can be identified by a karyotype.
Karyotype- a picture of a person’s chromosomes. Can be used to check
for chromosome abnormalities, like Down Syndrome & shows the sex
chromosomes.
8. What is nondisjunction?
Failure of chromosomes to separate during meiosis.
9. Match the following vocabulary terms:
___ The father of genetics
___ Square diagram used to determine
the outcome of a cross
___ A gene that, when present, is always
expressed or shown
___ A gene that is only shown when the
individual is homozygous
___ Different versions of a gene
A.
B.
C.
D.
E.
F.
G.
H.
I.
Dominant
Allele
Gregor Mendel
Punnett Square
Genotype
Phenotype
Recessive
Monohybrid Cross
Likelihood an event will occur
___ Actual gene make-up or combination
of alleles
___ Form of a trait that is observed
___ A genetic cross involving only 1 trait
___ Probability
10. Karyotypes: Answer the following questions:
Is this a male or female: Female
Normal or abnormal karyotype: Abnormal – missing the second sex-chromosome
11. Incomplete Dominance Punnett Square:
Purple Thingamadoodles are created due to incomplete dominance from Red (R) and
Blue (B) Thingamadoodles. Using a punnett square show all of the possible offspring from a cross
between two Purple Thingamadoodles.
R
R
B
B
RR
RB
RB
BB
Possible Genotypes (with %)
Possible Phenotypes (with %)
RR
RR – 25%
RB – 50%
BB – 25%
Red – 25%
Purple – 50%
Blue – 25%