Chapter 11 – Mendelian Patterns of Inheritance
11.1 Gregor Mendel (p 182-183)
1. When Mendel began breeding experiments, other breeders had different ideas about heredity. Place a check next to the statements that represent the ideas at the time.
a. _____ A cross between a red flower and a white flower results in all offspring have pink flowers.
b. _____ In a genetic cross, both parents contribute equally to the offspring.
c. _____ Parents of contrasting appearance always produce offspring of intermediate appearance.
Collectively, these concepts were known as the _______________________________________ Concept of Inheritance
2. Mendel’s work reflected several methods and advantages that contributed to his success. Place a check next to the statements that represent those methods and advantages.
a. _____ Each trait studied (seed shape, flower color) displayed three different phenotypes
b. _____ True-breeding plants produce offspring that look just like they do.
c. _____ Plants Mendel used could not self-pollinate.
d. _____ Mendel used mathematical calculations in his studies.
e. _____ Mendel discovered several intermediate trades in pea plants.
Collectively, Mendel’s study resulted in the _________________________ Theory of Inheritance.
11.2 Mendel’s Law of Segregation
3. Mendel performed several experiments. Place a check next to each of his interpretations and observations.
a. _____ F1 organisms contain only one copy for each hereditary factor.
b. _____ Factors separate when gametes form.
c. _____ Gametes fuse randomly during fertilization.
d. _____ The F1 generation always had a 3:1 ratio.
e. _____ Each gamete contains only one factor that determines inheritance.
Collectively, his observations resulted in the Law of ___________________________________.
4. The length of stem in the plants Mendel studied had two alleles: T (tall) and t (short). Using these letters, write the alleles for:
a heterozygous individual _________. A homozygous dominant _______ A homozygous recessive _______
5. When Mendel crossed true-breeding tall plants with true-breeding short plants, the F1 offspring were _________
When he crossed F1 x F1, what were the ratios of the offspring? _____________ tall; _________ short
6. If a plant’s phenotype is short, its genotype(s) can be ________________________
If a plant’s phenotype is tall, its genotype(s) can be __________________________
7. Among humans, the allele for widow’s peak hairline is dominant to the allele for a straight hairline. Consider the cross Hh x Hh. Use fractions to answer the questions.
a. What is the chance that either parent will produce a gamete with a dominant allele? ____ A recessive? ____
b. Using the multiplicative law of probability, what is the chance of a homozygous dominant offspring. Show your work! ________________________________________________
c. Using the multiplicative law of probability, what is the chance of a homozygous recessive offspring. Show your work! ________________________________________________
d. Using the additive law of probability, what is the chance of a heterozygous offspring. Show your work! ________________________________________________
8. In peas, yellow seed color is dominant to green. The key is: Y = _________________ y = _________________
Show a Punnett square for the cross Yy x Yy
What is the genotypic ratios among the offspring? ______________________________
What is the phenotypic ratios? _________________________________________
9. Gametes always combine at ________________________, and usually a ________________ number must be observed in order to verify the 3:1 ratio.
10. If two parents have detached earlobes (Ee), and they have two children with attached earlobes. What is the CHANCE that their third child will also have attached lobes?
_____________ %
11. In rabbits, if B = dominant black allele and b = recessive white allele.
What genotype could a white rabbit have? ______________
If a white rabbit is crossed with a homozygous black rabbit,
what is the genotype of ALL of their offspring? _________________
One-Trait Testcross
12. If you had a male black rabbit ( B _ ), what is the genotype of a female rabbit you could mate it with to determine the male’s genotype? ______________________________
This type of cross is called a ___________________________
13. In the cross above, what ratios would you expect in the offspring if the male is heterozygous? _________________
if the male is homozygous ? ________________
11.3 Mendel’s Law of Independent Assortment
14. A dihybrid cross is perfomed for two pea plants (TtGg). What are the genotypes of the GAMETES produced from a single parent? ____________________________________________________________
15. Four separate phenotypes were observed in the dihybrid cross, this lead to the LAW of ____________
16. What is the scientific name for the fruit fly? __________________________________________
17. Define “wild type” : __________________________________________________________
18. What are two mutant traits found among fruit flies? ___________________________
19. Consider the cross between two heterozygous fruit flies. LlGg x LlGg
Look at the trait for WINGS à What proportion of the offspring will have long wings? _________
What proportion of the offspring will have short wings? _________
Look at the trait for BODY COLOR à What proportion of the offspring be gray? _________
What proportion of the offspring will be ebony? _________
Using the multiplicative law of probability, determine how many will be:
(SHOW ALL YOUR WORK! I DO NOT WANT TO SEE A PUNNETT SQUARE)
Long winged and gray: ___________ Long winged and ebony: _________
Short winged and gray: ___________ Short winged and ebony: _________
11.4 Human Genetic Disorders
20. Examine the pedigree
a. What is the mode of inheritance? _______________________________
b. What is the genotype of A? ___________
c. What is the genotype B? ___________
d. What is the genotype of D? ____________
21. Which of the following is TRUE for autosomal dominant traits? (check)
a. ___ Two affected parents can produce an unaffected child
b. ___ Two unaffected parents have a 25% chance of having an affected offspring.
c. ___ Males are affected with more frequency than females.
d. ___ Affected children will always have an affected parent.
22. Match the description to the disorder:
1. ____cystic fibrosis a. lysosomal storage disease
2. ____ Huntington disease b. abnormal hemoglobin
3. ____ Neurofibromatosis c. progressive nervous system degeneration
4. ____ Phenylketonuria (PKU) d. disorder affecting mucous and sweat glands
5. ____ Tay-Sachs Disease e. essential enzyme deficiency
6. ____ Sicke Cell Disease f. abnormal growth of long bones
7. ____ Achondroplasia g. benign tumors in the skin
23. Show the Punnett Square of two (heterozygous) dwarfs who have children. What are the chances that their children will be of normal stature? _________________
11.5 Beyond Mendel
24. What does “multifactoral” mean? _________________________________________
25. What are the three phenotypes found in Four-O’clocks? _____________________________
26. If a straight haired person has children with a curly haired person, all of their children are ___________ haired.
27. Which two blood alleles are codominant? _____________ Which is recessive? ______________
28. The Rh allele is inherited [ separately from / with ] the blood type alleles.
29. ___________________ alleles are quantitative and may be located on separate ________________
30. The color of wheat seeds is determined by the number of ____________________ alleles present.
31. Name two human traits that are polygenic: ________________________________________
32. What is epistasis? ___________________________________________________
Give an example of an epistatic allele: _________________________________________
33. What environmental factor can affect height in humans? ________________________________
34. What happens to the areas of a Himalyan rabbit that remain cold? ____________________________
What other animal has this same pattern of gene expression? __________________________
35. What environmental factor affects the appearance of the water buttercup? _________________
