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Unit 7 Study Guide
Name _____________________
1.
What is the only purpose of meiosis? What are the only cells produced in meiosis?
2.
How are the events of Metaphase I of meiosis different than Metaphase II? Draw a picture to illustrate.
3.
Define and DRAW Crossing-over. When does crossing over occur?
4.
Define Independent assortment. When does independent assortment occur?
5.
What is genetic diversity? How do Crossing-over and Independent Assortment lead to so many different possible
combinations of genes? Be specific for each one!
6.
Explain how nondisjunction during meiosis can lead to abnormal offspring. Give 1 example of a nondisjunction disorder.
7.
Using the letter “T” for the allele, write an example of homozygous dominant, homozygous recessive, and heterozygous
individuals.
8.
Explain how the following terms relate to each other:
a. DNA – Chromosome
9.
b.
Gene – Chromosome
c.
Gene – Trait
d.
Trait – Allele
Per. ______
If short tails are dominant to long tails, what are the phenotypic and genotypic ratios of a cross between a dog with a long
tail and a dog with a short tail (who had a parent with a long tail)?
10. Complete the following table that summarizes the 4 basic genetic crosses: (B=black; b =brown)
Word Cross
Genotype Cross
BB x bb
Offspring Genotype Ratio
Offspring Phenotype Ratio
Homozygous Dominant x
Heterozygous
1 BB: 2 Bb: 1 bb
2 Black : 2 Brown
11. How are Incomplete Dominance and codominance different from each other? Give examples of each type of inheritance.
12. Show the expected genotype and phenotype ratios of a cross between a man with type A blood and a woman with type B
blood (both the man and woman had parents with type O blood).
13. What is the difference between Autosomes and Sex Chromosomes? What sex chromosomes determine male? Female? Why
do sex-linked traits affect males more than females?
14. Show the expected genotype and phenotype ratios of a cross between a man who is colorblind and a woman who has
normal vision (but her father was colorblind).
15. List 2 different environmental factors that can potentially affect the phenotype.
16. What is a mutation? Why would a mutation on a sex cell affect offspring but a mutation on a body cell only affect the
individual organism?
17. Explain how a woman who smokes during pregnancy can affect her genes, her daughter’s genes, and then her future
grandchildren’s genes.
18. A woman has hemophilia (a recessive, sex-linked trait). What are the genotypes of her parents? Using a Punnett Square,
show the cross that results in the woman inheriting hemophilia.
a. Is this pedigree showing a dominant or
recessive disorder?
19. Pedigrees:
b. How do you know?
c. Write all possible genotypes for individuals
shown on the pedigree.
20. In a pedigree, what do the circles represent? Squares represent? What does it mean if a circle or square is completely shaded?
What does it mean if it is only half-shaded? What if there is no shading?