Genetics Test Review Sheet



Name: _______________________ Date _______________ Block ____

Genetics Review Sheet

Directions: Answer these on a separate sheet of paper.

1. Who is considered the father of genetics? Mendel

2. Describe these three principles.

• Principle of Dominance: Some alleles are dominant and others are recessive

• Principle of Segregation: allele pairs separate during gamete formation and randomly unite during fertilization

• Principle of Independent Assortment: Traits segregate independently of each other during formation of gametes

3. What are alternate forms of a gene called? Alleles

4. Why is a Punnett Square useful? It can be used to predict the genotype and phenotype combos

5. What is genotype? The genetic makeup of an organism

6. What is phenotype? The expressed physical characteristics of an organism

7. What is a trait? A specific characteristic of an individual

8. Why might a recessive allele not be expressed (not show up)? A dominant allele masks it.

9. Two parents with the genotype Ss for a genetic disorder caused by a recessive allele are crossed. What would the genotype for the genetic disorder be? Show the Punnett square and give the phenotypic ratio.

Genotype for genetic disorder: ss

Phenotypic Ratio: 3:1

[pic] 3 Normal

1 with genetic disorder

10. Show the cross for a genetic disorder caused by a dominant allele between two heterozygous parents. Will any of their children inherit this disorder?

75% of children with inherit disorder

11. Using letter R, create the following.

Homozygous dominant: __RR______

Homozygous recessive: __rr_________

Heterozygous:__Rr________________

12. In order to show the phenotype of a disorder caused by a recessive allele, what must the genotype be? rr

13. What is co-dominance? Cross where phenotypes produced by both alleles are completely expressed. Ex. AB blood type

14. How does the phenotype appear when co-dominant alleles are present? Both are expressed

15. What is incomplete dominance? One allele is not completely dominant over another

16. How does the phenotype appear when incompletely dominant alleles are present? Phenotype lies somewhere in between Ex. Red & White flowers crossed form pink phenotype

17. What are sex-linked traits? A trait carried on the sex chromosomes

18. Give three examples of sex-linked traits. Color-blindness, hemophilia, baldness

19. What is a polygenic trait? Trait controlled by two or more genes Ex. Skin color

20. What type of gene is Huntington’s disease caused by: dominant or recessive?

21. What must a female’s genotype be if she shows the phenotype for a sex-linked trait? XbXb

22. What is a clone? A genetically identical copy of a gene

23. What happens during crossing over? An area of a chromatid is exchanged or crosses over with the matching area of its pair

24. What does crossing over result in? genetic variation

Complete Punnett Square Problems

25. Monohybrid (Co-dominant)

PROBLEM:  Cross two heterozygous tan cows.  Give genotypic and phenotypic ratios.  BB=Black, BW=tan, and WW=white

1 Black cows B W

|BB |BW |

|BW |WW |

2 Tan cows

1 White cow

26. Monohybrid (sex-linked)

PROBLEM:  Cross a female carrier for hemophilia with a male with hemophilia.  H=normal, and h=hemophilia See separate Punnett Square page

27. Monohybrid (Multiple Alleles)

PROBLEM:  Cross a person with type AB blood with a person who is heterozygous for type A blood. See separate Punnett Square page

28. Alice has type A blood and her husband Mark has type B blood. Their first child, Amanda, has type O blood. Their second child, Alex, has type AB blood.

What is Alice’s genotype? ___AO_______

What is Mark’s genotype? ___BO________

Show how you found the answer by completing a Punnett square(s)

See separate Punnett Square page

29. Colorblindness is inherited as a sex-linked recessive disease. An affected male marries a heterozygous female. Draw a Punnett square of the possible offspring. What is the chance that they will have an affected child? Could any of their daughters be affected? See separate Punnett Square page

Chapter 11 Introduction to Genetics

Compare/Contrast Table

Comparing Processes

Using information from the chapter, complete the compare/contrast table below. If there is not enough room on the table to write your answers, place them on a separate sheet of paper.

| |Mitosis |Meiosis |

|Function |Growth, regeneration of new cells |Production of gametes for sexual reproduction |

|Location in body |All body cells |Only in certain cells of the reproduction system |

|Number of Daughter cells |Two |Four |

|Change in chromosome number |None |Diploid to Haploid |

|Number of phases |Four |Eight: Four in meiosis I and four in meiosis II |

|Number of cell divisions |One |Two |

|Difference in DNA between parent cell and daughter |None |Homologous chromosomes assort independently, so |

|cells | |each gamete has a unique combination of alleles. |

20. Compare and Contrast Mitosis and Meiosis

-----------------------

S s

SS

Ss

Ss

ss

S

s

G g

G

g

GG

Gg

gg

Gg

B

W

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