Download Punnett Squares

 HBiology – Genetics Test Review Sheet 
(Not a comprehensive list – also study notes, worksheets, labs, text)
 Vocabulary
Gene, allele, chromosome, dominant, recessive, heterozygous, homozygous, purebred,
truebreeding, autosome
 Gregor Mendel
 Self pollination vs. cross pollination
 Law of Dominance
 Law of Segregation
 Law of Independent Assortment
 Punnett Squares
 Monohybrid
 Dihybrid (short and long methods)
 Test cross
 Genotypes and phenotypes of offspring
 Genotypic and phenotypic ratios
 MONOHYBRID CROSS
 Genotypic Ratio  #homo dom: # hetero : # homo rec
 Phenotypic Ration  # displaying dom phenotype: # displaying rec pheno
 DIHYBRID CROSS
 Genotypic Ratio  too complex to do for Dihybrid
 Phenotypic ratio 
# dom1, dom2 : # dom1, rec2 : # rec1, dom2 : #rec1, rec2
 INCOMPLETE DOMINANCE
 Genotypic Ratio: same as monohybrid
 Phenotypic Ratio  # dom pheno : # blended pheno : # rec phenol
 Probability
 Gene Linkage
 Walter Sutton
 Chromosomal Theory of Inheritance
 Process of mapping genes on a chromosome
 Sex Linked Inheritance
 Sex determination in humans
 Sex chromosomes for males, females
 Inheritance of sex linked traits (punnett squares)
 Examples and characteristics of sex-linked traits (colorblindness, hemophilia)
 Miscellaneous Forms of Inheritance
 Incomplete dominance
 Polygenic inheritance
 Codominant
 Multiple alleles – ABO bloodgroup
 Examples of each
Review Questions for Genetics Test (Chapter 9, 10.1 and portions of 11)
1.
Using the pea trait for “height” (i.e. tall or short), please describe the genotype of a plant who is:
a. homozygous dominant
d. short
b. heterozygous
e. a carrier for shortness
c. homozygous recessive
2. Describe the phenotypes for each of the plants above.
3. Crease a monohybrid punnett square for a cross between an organism who is heterozygous for
plant height and a plant who is homozygous recessive for plant height. Determine the genotypic
and phenotypic ratios for each.
4. What would be the phenotypic ratio for the following cross: TtSs x TtSs?
5. What gametes would the organisms in #4 produce?
6. Define probability, allele and gene.
7. Why would you need to do many crosses to get a ratio close to the expected probability?
8. What is Gregor Mendel the father of?
9. Which of Mendel’s laws explains why recessive traits are sometimes masked?
10. Which of Mendel’s laws explains why each daughter cell in meiosis differs from the parent cell?
11. What is a test cross? Why would you need to do one?
12. What are linked genes?
13. How could linked genes become separated? What factor increases the probability that linked
genes might be separated?
14. What is the genotype (ch. 23 only) for a male? A female?
15. What are the chances that a normal-vision male and a colorblind female will have a male who is
colorblind? A female?
16. What is hemophilia?
17. Can a female carrier for hemophilia and a hemophiliac male have male children without
hemophilia? Females without the disorder?
18. Why do males tend to inherit X-linked disorders more frequently?
19. Give an example of an organism exhibiting each of the following?
a. incomplete dominance
c. polygenic trait
b. codominance
d. multiple allele
20. Why is blood type AB considered the universal recipient? Why is blood type O considered the universal
donor?
    GENETICS PROBLEMS ON THE BACK    
1. The genotype of F1 individuals in a tetrahybrid cross is AaBbCcDd. Assuming independent assortment of
these four genes, what are the probabilities that F2 offspring would have the following genotypes? Remember
it is easiest to treat each gene separately as a monohybrid cross and then combine the probabilities.
a. aabbccdd
b. AaBbCcDd
c. AABBCCDD
d. AaBBccDd
e. AaBBCCdd
2. Among Hereford cattle there is a dominant allele called polled; individuals with this allele lack horns. After
college, you become a cattle baron and stock your spread entirely with polled cattle. You personally check each
cow to be sure that none possess horns, and none do. Among the calves that year, however some grow horns.
Angrily you dispose of them and check to see that no horned adult has gotten into your pasture. None has. And
yet the next year, more horned calves are born. What is the source of your problem?
3. The shape of radishes may be long (LL), round (ll) or oval (Ll). Color may be red (RR), white (rr), or purple
(Rr). If a long, white strain is crossed with a round, red strain, what phenotypic proportions are expected in the
F1? In the F2? Is this an example of complete or incomplete dominance? Why?
4. The normal daughter of a man with hemophilia marries a man who is normal for the trait.
a. What is the probability that a daughter will be a hemophiliac? A son?
b. If the couple has 4 sons, what is the probability that all four will be born with hemophilia?
c. If the couple has 4 children, what is the probability that all four will be normal sons?
5. Raccoons have rings around their tails and a habit of washing their food in water before eating it. Suppose
that both of these traits are controlled via incomplete dominance so that wide bands on the tail are BB, medium
sized bands are Bb, and narrow bands are bb and that washing all their food is WW, washing some of their food
is Ww, and washing no food is ww. How many of each genotype will be in the F1 generation resulting from a cross
of two raccoons, both with medium sized tail bands and that wash some of their food (assume 16 offspring)?