Science 10
Name:
Date:
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Block:
REVIEW SHEET
Terms & Definitions:
1. Different forms of a specific gene
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2. The passing of traits from parents to offspring
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3. The crossing of two individuals with two different alleles ______________________________
4. In a pair of alleles, the one that is “stronger”
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5. In a pair of alleles, the one that is “masked by the stronger one __________________________
6. A combination of alleles (e.g. BB, Bb, bb)
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7. The outward (physical) appearance of the organism
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8. An organism that is homozygous dominant for an allele ________________________________
9. An organism that is homozygous recessive for an allele ________________________________
10. The “father of genetics” (Austrian monk)
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11. A table used to predict the chance of genotype occurring _______________________________
Question:
1. Explain at least three reasons why pea plants were used in the original heredity experiments.
Use A Punnett Square To Answer The Following Questions!
2. In humans, double-jointedness (D) is dominant to normal joints (d). Cross a heterozygous,
double-jointed female to a male with normal joints. What ratio of the offspring will be double
jointed?
Punnett Square
Ratio of double jointed offspring
3. In mice, black coat colour (B) is dominant over white (b). Cross a homozygous dominant
mouse with a homozygous recessive mouse.
a) What are the genotypic and phenotypic ratios of the F1 generation?
Punnett Square
Genotypic ratio
Phenotypic ratio
b) What are the genotypic and phenotypic ratios of the F2 generation?
Punnett Square
Genotypic ratio
Phenotypic ratio
4. Incomplete dominance: Red coat colour (R) is incompletely dominant over white coat colour
(W) in cattle; the hybrid (RW) is roan coloured.
a) If you cross a homozygous red female cow with a homozygous white bull, what are the
genotypic and phenotypic ratios of the offspring?
Punnett Square
Genotypic ratio
Phenotypic ratio
b) If you cross a roan bull with a white cow, what is the probability of getting roan offspring?
Punnett Square
Probability of a roan offspring
5. Multiple alleles: ABO blood types. If a man with the blood type AB produced children with a
woman of blood type A (IAi), what are the genotypic and phenotypic ratios of the offspring?
Punnett Square
Genotypic ratio
Phenotypic ratio
6. Sex linkage: Coat colour in cats is sex-linked. Black (B) is dominant to ginger (b). A hybrid
(Bb) will produce an individual with a tortoiseshell coat colour
a) Cross a homozygous black female cat to a ginger male cat and write the genotypic and
phenotypic ratio of their offspring.
Punnett Square
Genotypic ratio
b) Is it possible to get a male tortoiseshell cat? Explain.
Phenotypic ratio
7. Sickle cell anemia is a genetic disease which causes malformation of the red blood cells (some
of them collapse into a sickle shape). It is caused by one gene only. Individuals who are
homozygous for sickle cell anemia tend to die as small children, by hybrids (“carriers”) suffer
much less and often live long enough to reproduce.
a) If a male carrier is crossed with a female carrier, what is the probability of having a child with
the actual disease?
Punnett Square
Probability of a child with the disease
b) Is sickle cell anemia a sex-linked trait? How can you tell?
c) Is the gene for sickle cell anemia dominant or recessive? Explain.
8. Gene Interaction: In the budgerigar bird, blue colour (B) is incompletely dominant over yellow
colour (Y). Heterozygous birds are (BY) are green. In addition, long wings (S) are dominant
over short wings (s).
a) Cross a long-winged, blue bird (SsBB) with a long-winged, green bird (SsBY) using the 16-box
Punnett square.
b) What is the phenotypic ratio of the offspring?