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Biology
Name ____________________________________
Genetics Test Review
Period ___________ Date ___________________
Vocabulary
Dominant: Allele that hides the presence of another
F1 Generation: Offspring of the parent generation
Heredity: Transmission of characteristics from parents to offspring
Recessive: Allele that is hidden a majority of the time
Phenotype: Physical characteristic of an organism
Genotype: Genetic make-up of an organism
Allele: Different choices/options for a gene
Homozygous: Having 2 of the same allele for a trait
Heterozygous: Having 2 different alleles for a trait
Gregor Mendel: Austrian Monk, “Father of Genetics”
Practice Problems
In otters. black fur is dominate to white fur. Cross a homozygous black-furred otter with a
white-furred otter
Ff
Ff
Ff
Ff
P1 __FF_____ × __ff_____
1. Give all possible genotypes of the F1 generation. ______Ff___________________________________
2. Give all possible phenotypes of the F1 generation. ______black fur____________________________
3. What is the ratio of black fur to white fur otters in the F1? _____4:0__________________
4. What percent of the F1 generation will be:
a. homozygous? ______0%_______________________
b. heterozygous? ______100%_____________________
c. black fur?
_______100%____________________
d. homozygous dominant? __100%__________________
e. homozygous recessive? ___0%___________________
In buzzards, baldness is dominate over fuzziness. Cross a fuzzy buzzard with a
heterozygous bald buzzard.
Bb
Bb
P1 __bb_____ × ___Bb____
bb
bb
5. Give all possible genotypes of the F1 generation. ____Bb, bb__________________________________
6. Give all possible phenotypes of the F1 generation. ____bald, fuzzy_____________________________
7. What is the ratio of fuzzy buzzards to bald buzzards in the F1? ____2:2 or 1:1_____________________
8. What percent of the F1 generation will be:
a. homozygous? _____50%________________________
b. heterozygous? _____50%________________________
c. fuzzy? __________50%_________________________
d. bald? __________50%_________________________
e. homozygous dominant? ___0%__________________
f. homozygous recessive? ____50%__________________
In llamas, floppy ears (E) are dominant to pointy ears. Also in llamas, bowlegs (b) are recessive. A llama
with floppy ears (heterozygous) and bowlegs is crossed with one that is heterozygous for both traits.
P1: __Eebb_____ x ____EeBb_____
9. What fraction of the F1 generation:
a. looks like their daddy?
____6/16 or 3/8___________
b.
____6/16 or 3/8___________
looks like their mommy?
c. is completely heterozygous? ____4/16 or 1/4___________
d. shows both recessive traits? ____2/16 or 1/8___________
11. How many:
a. different phenotypes are present in the F1? ____4___________
b. different genotypes are present in the F1?
____6___________
c. kinds of gametes can the daddy make?
____2___________
d. kinds of gametes can the mommy make?
____4___________
EEBb EEBb EeBb EeBb
EEbb
EEbb
Eebb
Eebb
EeBb
EeBb
eeBb
eeBb
Eebb
Eebb
eebb
eebb
Harry Potter loves his owl Hedwig. He is afraid something might happen to her in the future and wants to mate
Hedwig with another owl so that he may have another owl similar to Hedwig. Hedwig is homozygous dominant
for white feathers and homozygous recessive for a short beak. Harry mates her with a homozygous recessive
black feathered owl that is heterozygous for a long beak. Answer the following question about the parents and
baby owls.
P1: ____FFss_______ x ____ffSs_______
13. What fraction of the F1 generation:
e. looks like their daddy?
____8/16 or 1/2___________
f.
____8/16 or 1/2___________
looks like their mommy?
g. is completely heterozygous? ____8/16 or 1/2__________
FfSs
FfSs
FfSs
FfSs
Ffss
Ffss
Ffss
Ffss
FfSs
FfSs
FfSs
FfSs
Ffss
Ffss
Ffss
Ffss
h. shows both recessive traits? ____0/16___________
14. How many:
a. different phenotypes are present in the F1? ______2_________
b. different genotypes are present in the F1?
______2_________
Incomplete Dominance: _____________________________________________________________
15. In snapdragons, flower color is controlled by incomplete dominance. The two alleles are red (R)
and white (r). The heterozygous genotype is expressed as pink.
a. What is the phenotype of a plant with the genotype RR? ___Red________
b. What is the phenotype of a plant with the genotype rr? ____White_______
c. What is the phenotype of a plant with the genotype Rr? ____Pink
16. A pink-flowered plant is crossed with a white-flowered plant.
P1: _Rr___ X _rr___
Rr
rr
What is the probability of producing a pink-flowered plant? _50___%
Rr
rr
17. What cross will produce the most pink-flowered plants? Show a punnett square to support your answer.
P1: _RR___ X _rr___
Rr
Rr
Rr
Rr
Codominance: ____________________________________________________________________________
18. In some chickens, the gene for feather color is controlled by codiminance. The allele for black is
(B) and the allele for white is (B’). The heterozygous phenotype is known as erminette.
a. What is the genotype for black chickens? __BB____
b. What is the genotype for white chickens? ___B’B’___
c. What is the genotype for erminette chickens? _BB’___
19. If two erminette chickens were crossed, what is the probability that:
P1: _BB’___ X _BB’___
BB
BB’
BB’
B’B’
a. They would have a black chick? __25____%
b. They would have a white chick? __25____%
20. Explain the difference between incomplete dominance and codominance: _Incomplete: neither trait shows
dominance and you get a blended effect. Co-Dominance: both traits show dominance and both traits are
seen at the same time.
21. Explain the Law of Dominance: Dominant- Allele hides the presence of another allele/ capital letter,
Recessive- allele is hidden/ lowercase letter
22. What are punnett squares used for? to show possible offspring outcomes
23. What is the difference between Monohybrid and a Dihybrid? 1 gene verse 2 genes
24. Explain what the difference between Chromosomes and Genes are. Chromosomes are organized and
compacted DNA found in dividing cells. Genes are sections of chromosomes that will code for a specific
trait.