| Gregor Mendel’s Discoveries |
| 1. |
Explain how Mendel’s particulate mechanism differed from the blending theory of inheritance. |
| 2. |
Define the following terms: true-breeding, hybridization, monohybrid cross, P generation, F1 generation, and F2 generation. |
| 3. |
List and explain the four components of Mendel’s hypothesis that led him to deduce the law of segregation. |
| 4. |
Use a Punnett square to predict the results of a monohybrid cross, stating the phenotypic and genotypic ratios of the F2 generation. |
| 5. |
Distinguish between the following pairs of terms: dominant and recessive; heterozygous and homozygous; genotype and phenotype. |
| 6. |
Explain how a testcross can be used to determine if an individual with the dominant phenotype is homozygous or heterozygous. |
| 7. |
Use a Punnett square to predict the results of a dihybrid cross and state the phenotypic and genotypic ratios of the F2 generation. |
| 8. |
State Mendel’s law of independent assortment and describe how this law can be explained by the behavior of chromosomes during meiosis. |
| 9. |
Use the rule of multiplication to calculate the probability that a particular F2 individual will be homozygous recessive or dominant. |
| 10. |
Given a Mendelian cross, use the rule of addition to calculate the probability that a particular F2 individual will be heterozygous. |
| 11. |
Use the laws of probability to predict, from a trihybrid cross between two individuals that are heterozygous for all three traits, what expected proportion of the offspring would be:
a. homozygous dominant for the three traits
b. heterozygous for all three traits
c. homozygous recessive for two specific traits and heterozygous for the third |
| 12. |
Explain why it is important that Mendel used large sample sizes in his studies. |
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Extending Mendelian Genetics |
| 13. |
Give an example of incomplete dominance and explain why it does not support the blending theory of inheritance. |
| 14. |
Explain how phenotypic expression of the heterozygote differs with complete dominance, incomplete dominance, and codominance. |
| 15. |
Explain why Tay-Sachs disease is considered recessive at the organismal level but codominant at the molecular level. |
| 16. |
Explain why genetic dominance does not mean that a dominant allele subdues a recessive allele. Illustrate your explanation with the use of round versus wrinkled pea seed shape. |
| 17. |
Explain why dominant alleles are not necessarily more common in a population. Illustrate your explanation with an example. |
| 18. |
Describe the inheritance of the ABO blood system and explain why the IA and IB alleles are said to be codominant. |
| 19. |
Define and give examples of pleiotropy and epistasis. |
| 20. |
Describe a simple model for polygenic inheritance and explain why most polygenic characters are described in quantitative terms. |
| 21. |
Describe how environmental conditions can influence the phenotypic expression of a character. Explain what is meant by “a norm of reaction.” |
| 22. |
Distinguish between the specific and broad interpretations of the terms phenotype and genotype. |
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Mendelian Inheritance in Humans |
| 23. |
Explain why studies of human inheritance are not as easily conducted as Mendel’s work with his peas. |
| 24. |
Given a simple family pedigree, deduce the genotypes for some of the family members. |
| 25. |
Explain how a lethal recessive allele can be maintained in a population. |
| 26. |
Describe the inheritance and expression of cystic fibrosis, Tay-Sachs disease, and sickle-cell disease. |
| 27. |
Explain why lethal dominant genes are much rarer than lethal recessive genes. |
| 28. |
Give an example of a late-acting lethal dominant gene in humans and explain how it can escape elimination by natural selection. |
| 29. |
Define and give examples of multifactorial disorders in humans. |
| 30. |
Explain how carrier recognition, fetal testing, and newborn screening can be used in genetic screening and counseling. |
