Genetics Problems

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Genetics Problems

This is an on-line version of the same Genetics Problem questions included at the end of the chapter in your textbook. Use this version to quickly and easily submit your work to your instructor or teaching assistant.

1. Name some attributes of a model organism. In what sense are garden peas or fruit flies a "model?"
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

2. Why is the allele for wrinkled seed shape in garden peas considered recessive?
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

3. The alleles found in haploid organisms cannot be dominant or recessive. Why?
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

4. Biologists no longer use the term pure line except in a historical context. Instead, they simply refer to "pure-line" individuals as homozygotes. Explain.
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

5. The genes for the traits that Mendel worked with are either located on different chromosomes or are so far apart on the same chromosome that crossing over almost always occurs between them. How did this circumstance help Mendel recognize the principle of independent assortment?
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

6. The text claims that Mendel worked with the simplest possible genetic system. Do you agree with this statement? Why or why not?
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

7. The artificial sweetener NutraSweet(tm) consists of a Phenylalanine molecule linked to aspartic acid. The labels of diet sodas that contain NutraSweet include a warning to people with PKU. Why? Make a general comment on how aspects of an individual’s environment affect the individual’s phenotype using an example other than PKU.
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

8. When Sutton and Boveri published the chromosome theory of inheritance, research on meiosis had not yet established that paternal and maternal homologs actually do assort independently. Then in 1913, Elinor Carothers published a paper about a grasshopper species with an unusual karyotype. One chromosome had no homolog (meaning no pairing partner at meiosis I). Another chromosome had homologs that could be distinguished under the light microscope. If chromosomes assort independently, how often should Carothers have observed each of the four products of meiosis shown in the figure? Explain. of the alleles responsible for the spotted and unspotted phenotypes? Of orange and yellow? What can you conclude about the genotype of the original plant that had orange, spotted flowers?

To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

9. In humans, the ABO blood type is a polymorphic trait. Describe the alleles and genotypes responsible for the polymorphism. Suppose a woman with blood type O married a man with blood type AB. What phenotypes and genotypes would you expect to observe in their offspring, and in what proportions?
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

10. A plant with orange-spotted flowers was grown in the greenhouse from a seed collected in the wild. The plant was self-pollinated and gave rise to the following progeny: 88 orange with spots, 34 yellow with spots, 32 orange with no spots, and 8 yellow with no spots. What can you conclude about the dominance relationships
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

11. As a genetic counselor, you routinely advise couples about the possibility of genetic disease in their offspring based on their family histories. This morning you met with an engaged couple, both of whom are phenotypically normal. The man, however, has a brother who died of Duchenne-type muscular dystrophy. This is an X-linked condition that results in death before the age of 20. The allele responsible for the disease is recessive. His prospective bride, whose family has no history of the disease, is worried that the couple’s sons or daughters might be afflicted.

How would you advise this couple?

The sister of this man is planning to marry his fiancé’s brother. How would you advise this second couple?
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

12. Study the experiment illustrated in Figure 10.8 and 10.9. To further test his hypothesis of independent assortment, Mendel let the F₂ progeny from this experiment self-fertilize. Then he examined the phenotypes of the F₃ generation.

Consider the F₂ individuals that have one dominant and one recessive trait. When they self-fertilize, what fraction of these individuals with will be "pure line" for these traits?

Consider the F₂ individuals that have both dominant traits. When they self-fertilize, what fraction of these individuals with will be "pure line" for these traits?
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

13. Suppose that you are heterozygous for two genes that are located on different chromosomes. You carry alleles A and a for one gene and alleles B and b for the other. Draw a diagram that illustrates what happens to these genes and alleles when meiosis occurs in your reproductive tissues. Label the stages of meiosis, the homologous chromosomes, sister chromatids, non-homologous chromosomes, genes, and alleles. Be sure to list all of the genetically different gametes that could form and how frequently each type should be observed. On the diagram, identify the events responsible for the principle of segregation and the principle of independent assortment.
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

14. Mr. Spock was the first officer of the starship Enterprise in the 1970s-era TV series called Star Trek. Mr. Spock’s father came from the planet Vulcan and his mother from planet Earth. A Vulcan has pointed ears and a heart located on the right side of the chest. Mr. Spock has both of these traits, which are known to be determined by two different genes, with two alleles each. Suppose that Mr. Spock married an Earth woman and that they had many children. About half of their children look like Spock (pointed ears and right-sided heart) and about half look like their mother (rounded ears and left-sided heart).

What would Mendel predict the progeny phenotypes and ratios to be? Explain your answer using formal genetic terminology.

How do you explain the actual results?

To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

15. In the television program Star Trek, a group of human-like organisms called Klingons are the archenemies of the Enterprise crew. In Klingons, one gene determines hair texture while another determines whether the individual will have a saggital crest (a protrusion on the forehead). The two genes are not linked.
K = curly klingon hair (dominant)
k = silky earthling-like hair (recessive)
S = large saggital crest (dominant)
s = smooth, flat earthling-like forehead (recessive)

To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.




1.	Name some attributes of a model organism. In what sense are garden peas or fruit flies a "model?" To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



2.	Why is the allele for wrinkled seed shape in garden peas considered recessive? To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



3.	The alleles found in haploid organisms cannot be dominant or recessive. Why? To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



4.	Biologists no longer use the term pure line except in a historical context. Instead, they simply refer to "pure-line" individuals as homozygotes. Explain. To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



5.	The genes for the traits that Mendel worked with are either located on different chromosomes or are so far apart on the same chromosome that crossing over almost always occurs between them. How did this circumstance help Mendel recognize the principle of independent assortment? To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



6.	The text claims that Mendel worked with the simplest possible genetic system. Do you agree with this statement? Why or why not? To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



7.	The artificial sweetener NutraSweet(tm) consists of a Phenylalanine molecule linked to aspartic acid. The labels of diet sodas that contain NutraSweet include a warning to people with PKU. Why? Make a general comment on how aspects of an individual’s environment affect the individual’s phenotype using an example other than PKU. To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



8.	When Sutton and Boveri published the chromosome theory of inheritance, research on meiosis had not yet established that paternal and maternal homologs actually do assort independently. Then in 1913, Elinor Carothers published a paper about a grasshopper species with an unusual karyotype. One chromosome had no homolog (meaning no pairing partner at meiosis I). Another chromosome had homologs that could be distinguished under the light microscope. If chromosomes assort independently, how often should Carothers have observed each of the four products of meiosis shown in the figure? Explain. of the alleles responsible for the spotted and unspotted phenotypes? Of orange and yellow? What can you conclude about the genotype of the original plant that had orange, spotted flowers? To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



9.	In humans, the ABO blood type is a polymorphic trait. Describe the alleles and genotypes responsible for the polymorphism. Suppose a woman with blood type O married a man with blood type AB. What phenotypes and genotypes would you expect to observe in their offspring, and in what proportions? To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



10.	A plant with orange-spotted flowers was grown in the greenhouse from a seed collected in the wild. The plant was self-pollinated and gave rise to the following progeny: 88 orange with spots, 34 yellow with spots, 32 orange with no spots, and 8 yellow with no spots. What can you conclude about the dominance relationships To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



11.	As a genetic counselor, you routinely advise couples about the possibility of genetic disease in their offspring based on their family histories. This morning you met with an engaged couple, both of whom are phenotypically normal. The man, however, has a brother who died of Duchenne-type muscular dystrophy. This is an X-linked condition that results in death before the age of 20. The allele responsible for the disease is recessive. His prospective bride, whose family has no history of the disease, is worried that the couple’s sons or daughters might be afflicted. How would you advise this couple? The sister of this man is planning to marry his fiancé’s brother. How would you advise this second couple? To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



12.	Study the experiment illustrated in Figure 10.8 and 10.9. To further test his hypothesis of independent assortment, Mendel let the F₂ progeny from this experiment self-fertilize. Then he examined the phenotypes of the F₃ generation. Consider the F₂ individuals that have one dominant and one recessive trait. When they self-fertilize, what fraction of these individuals with will be "pure line" for these traits? Consider the F₂ individuals that have both dominant traits. When they self-fertilize, what fraction of these individuals with will be "pure line" for these traits? To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



13.	Suppose that you are heterozygous for two genes that are located on different chromosomes. You carry alleles A and a for one gene and alleles B and b for the other. Draw a diagram that illustrates what happens to these genes and alleles when meiosis occurs in your reproductive tissues. Label the stages of meiosis, the homologous chromosomes, sister chromatids, non-homologous chromosomes, genes, and alleles. Be sure to list all of the genetically different gametes that could form and how frequently each type should be observed. On the diagram, identify the events responsible for the principle of segregation and the principle of independent assortment. To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



14.	Mr. Spock was the first officer of the starship Enterprise in the 1970s-era TV series called Star Trek. Mr. Spock’s father came from the planet Vulcan and his mother from planet Earth. A Vulcan has pointed ears and a heart located on the right side of the chest. Mr. Spock has both of these traits, which are known to be determined by two different genes, with two alleles each. Suppose that Mr. Spock married an Earth woman and that they had many children. About half of their children look like Spock (pointed ears and right-sided heart) and about half look like their mother (rounded ears and left-sided heart). What would Mendel predict the progeny phenotypes and ratios to be? Explain your answer using formal genetic terminology. How do you explain the actual results? To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



15.	In the television program Star Trek, a group of human-like organisms called Klingons are the archenemies of the Enterprise crew. In Klingons, one gene determines hair texture while another determines whether the individual will have a saggital crest (a protrusion on the forehead). The two genes are not linked. K = curly klingon hair (dominant) k = silky earthling-like hair (recessive) S = large saggital crest (dominant) s = smooth, flat earthling-like forehead (recessive) To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

Chapter 10: Mendel and the Gene

Genetics Problems