Read Chapter 14.  Know all bold-face terms. Also study Fig. 15.2 on p. 275 of Chapter 15.

1. Understand the difference between the 'particulate' model and the 'blending' model of inheritance.
2. Clarify the definitions and distinctions between these terms:  character, trait,  gene, locus, allele.
3. Did Gregor Mendel observe genotypes or phenotypes in his experiments with garden peas?  Why not both?
4. Explain why an organism which is true-breeding for a certain character must be homozygous for that character.
5. In a monohybrid cross of true-breeding parents,what ratio of traits do you expect in the F₁ generation? What ratio do you expect in the F₂ generation?  (Assume this gene exhibits complete dominance).
6. After repeatedly observing the pattern of inheritance described in the answer to the previous question, Mendel developed an explanatory hypothesis which your text breaks down into 4 main ideas.  What are these 4 ideas?
7. Which give you more genetic information, phenotype or genotype?  Explain.
8. What is a testcross and why is it done?
9. Explain Mendel's law of segregation in terms of meiosis - that is,  when does the event described in Mendel's law occur during meiosis?
   (Be specific!)
10. In a dihybrid cross of true-breeding parents, what ratio of traits do you expect in the F₁ generation? What ratio do you expect in the F₂ generation? (Assume both genes exhibit complete dominance).
11. After observing the pattern of inheritance described in the answer to the previous question, Mendel developed his second law.  What is this law called?  At which specific phase of meiosis do you see the chromosomal basis of this law?
12. What is the Rule of Multiplication?  Give an example using the flipping of 2 coins. (Hint:  What is the probability of tossing 2 heads?  2 tails?  1 head and 1 tail?)
13. What is the Rule of Addition?  Give an example using the flipping of 2 coins.(Hint:  What is the probability of tossing 2 coins and having at least one head showing? Think of all the possible combinations...).
14. Understand the difference between complete dominance, incomplete dominance and codominance.  Understand that these terms depend on how a given genotype is expressed phenotypically.
15. The gene responsible for Tay Sachs disease exhibits co-dominance.  Does a person heterozygous for Tay Sachs have the disease?  Explain.

16. Why are lethal recessive alleles much more common than lethal dominant alleles?