Question 1

You learned that the phenotypic ratio of the F₂ generation of a typical test cross was 3:1. The genotypic ratio was 1:2:1. Why is a different ratio seen in a dihybrid cross? What conditions must be met for these parameters to be true?

Accepted Answer

The answer of You learned that the phenotypic ratio of...

Question 2

A woman with type A blood just had her first child. The child, like mother, had type A blood. What are all of the possible blood types of the father?

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The answer of A woman with type A blood just...

Question 3

The defective protein that actually causes cystic fibrosis is found in

Accepted Answer

The defective protein that causes cystic fibrosis is found in the cell membrane. It is a chloride ion channel called the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Mutations in the CFTR gene result in a dysfunctional CFTR protein that affects the movement of salt and water in and out of cells, causing the characteristic symptoms of cystic fibrosis.

Question 4

Duchenne muscular dystrophy (MD)is inherited from an X-linked recessive allele. What is the probability that a son with Duchenne MD inherited this disease from his biological father?

Accepted Answer

Duchenne muscular dystrophy is inherited in an X-linked recessive manner, meaning the defective gene is located on the X chromosome. Since males (XY) inherit their X chromosome from their mother and the Y chromosome from their father, a son cannot inherit the X-linked allele for Duchenne muscular dystrophy from his father.

Question 5

Explain how females with the chromosome constitution XXX are often fertile with normal intelligence and lead normal lives.

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The answer of Explain how females with the chromosome constitution...

Question 6

Compare and contrast the blending and particulate models of heredity.

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Question 7

A young couple already has three children and is expecting a fourth. Through a genetic test, the couple finds out that each of them is a carrier for cystic fibrosis. Upon counseling, they are informed that there is a 1 in 4 chance of their unborn child having cystic fibrosis and a 1 in 2 chance that he/she will be a carrier. Describe how the genetic counselor was able to determine these probabilities. The husband deduces that the child will be born with cystic fibrosis because the other 3 children do not have it. Explain why this reasoning is faulty. How would you handle the situation?

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The answer of A young couple already has three children...

Question 8

Before the 1900s, inheritance was thought to be blended. In other words, a father who was tall and a mother who was short would often have children who were of medium height. Indeed, this is often seen. As another example, a father with dark skin and a mother of lighter skin will often have children who have skin tones intermediate between their parents. How is this explained in light of modern genetics?

Accepted Answer

The answer of Before the 1900s, inheritance was thought to...

Question 9

Why do geneticists find that human genetics are rather hard to study, when compared to experimental organisms such as pea plants or fruit flies?

Accepted Answer

The answer of Why do geneticists find that human genetics...

Question 10

Most cases of red-green colorblindness are inherited as an X-linked recessive characteristic. Which of the following are possible if a woman, who is a carrier for colorblindness, has offspring with a male who is colorblind?

Accepted Answer

A woman who is a carrier for colorblindness has one normal X chromosome and one X chromosome with the colorblindness allele. A male who is colorblind has one normal Y chromosome and one X chromosome with the colorblindness allele. When they have offspring, the woman can pass on either her normal X chromosome or her X chromosome with the colorblindness allele to her sons. The man can only pass on his Y chromosome to his sons. Therefore, all of their sons will have normal color vision. The woman can pass on either her normal X chromosome or her X chromosome with the colorblindness allele to her daughters. The man can pass on either his normal X chromosome or his Y chromosome to his daughters. Therefore, half of their daughters will be carriers for colorblindness and half of their daughters will have normal color vision.

Question 11

Huntington's disease, an often fatal disease of the central nervous system, is inherited from a dominant allele. Furthermore, a person may not show symptoms of the disease until 30 - 50 years of age. Jack and Jill have been married for 40 years and have two children, Joe and Jane. Jack has recently been diagnosed with Huntington's disease. Assuming that Jane does not have the disease, determine the probability that one of the children will eventually have Huntington's. What is the probability that both Joe and Jane will inherit the disease?

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The answer of Huntington's disease, an often fatal disease of...

Question 12

Contrast Mendel's model of heredity with the blending model. Which one is a better description of the way traits are passed from one generation to the next?

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The answer of Contrast Mendel's model of heredity with the...

Question 13

Explain the role of the human genome project and modern medicine in helping to find a cure for cystic fibrosis.

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The answer of Explain the role of the human genome...

Question 14

Tall corn plants (T)are dominant to dwarf plants (tt). Solid green leaves (G)are dominant to leaves with a white tip (gg). A cross between two corn plants yielded the following phenotypes: 51 tall plants with a white tip on their leaves; 43 dwarf plants with solid leaves; 48 dwarf plants with white tips on their leaves; 45 tall plants with solid leaves. What are the genotypes of the parents that produced these plants?

Accepted Answer

The Punnett square for a cross between TtGg and ttgg will give us the expected phenotypes of the offspring:
 
From this Punnett square, we can see that the expected phenotypes of the offspring match the observed phenotypes given in the problem. Therefore, the parents must be TtGg and ttgg.

Question 15

You have just graduated from college as a business major, but have a special interest in genetics, ever since taking introductory biology with the new Life curriculum. Therefore, you decide to manage a pet store where you can dabble in animal breeding experiments. Your first investigation is with one of your childhood favorites, the guinea pig. When you cross a black guinea pig with a white guinea pig, three of the offspring are black and three are white. When you cross two of the black offspring you get six black and two white offspring. Which phenotype is most likely dominant? How do you know? What are the genotypes of the original parental guinea pigs?

Accepted Answer

The answer of You have just graduated from college as...

Question 16

Usually, an egg cell from a human female contains

Accepted Answer

An egg cell from a human female typically contains one X chromosome. This is because females have two X chromosomes (XX), and during the process of meiosis, which produces egg cells, these chromosomes are separated, resulting in egg cells that each carry a single X chromosome.

Question 17

What is the probability that a person would have cystic fibrosis if one of her parents was homozygous dominant and the other was a carrier for cystic fibrosis?

Accepted Answer

Cystic fibrosis is a recessive genetic disorder. If one parent is homozygous dominant (FF) and the other is a carrier (Ff), the possible genotypes for their offspring are FF and Ff. None of these genotypes result in cystic fibrosis (ff), so the probability is 0.

Question 18

Describe how you might analyze a pedigree to determine whether a particular condition is recessive or dominant, and X-linked or autosomal. For the sake of this question, ignore conditions such as multiple alleles, incomplete dominance, and other complications.

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The answer of Describe how you might analyze a pedigree...

Question 19

The hairline of some people drops downward near the center of the forehead and forms a distinct point. This condition is known as widow's peak. The alternative phenotype is a continuous hairline that does not drop down. A person with widow's peak always has an affected parent. Explain the inheritance pattern of widow's peak.

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The answer of The hairline of some people drops downward...

Question 20

You are a young M.D. and genetic researcher working in conjunction with the Human Genome Project. The charge of your laboratory is to research cures for genetic diseases. Recently the Centers for Disease Control and Prevention (CDCP)reported several cases of a new genetic disease dubbed the "Liver Quiver Syndrome." Even though little is known about the inheritance pattern of the disease, the abnormal allele(s)cause(s)a defective protein in the membrane structure of the Golgi apparatus. This abnormal protein prevents the processing of a protein that would eventually be secreted from liver cells. Symptoms include a spasm-like condition of the liver. Thus the name "Liver Quiver Syndrome." This disease is almost always fatal, killing most victims by age 50. As a doctor and genetic researcher, discuss the genetic research that must first be completed before a cure can be found.

Accepted Answer

The answer of You are a young M.D. and genetic...

Quiz 5: Patterns of Inheritance

You learned that the phenotypic ratio of the F₂ generation of a typical test cross was 3:1. The genotypic ratio was 1:2:1. Why is a different ratio seen in a dihybrid cross? What conditions must be met for these parameters to be true?

A woman with type A blood just had her first child. The child, like mother, had type A blood. What are all of the possible blood types of the father?

The defective protein that actually causes cystic fibrosis is found in

Duchenne muscular dystrophy (MD) is inherited from an X-linked recessive allele. What is the probability that a son with Duchenne MD inherited this disease from his biological father?

Explain how females with the chromosome constitution XXX are often fertile with normal intelligence and lead normal lives.

Compare and contrast the blending and particulate models of heredity.

Why do geneticists find that human genetics are rather hard to study, when compared to experimental organisms such as pea plants or fruit flies?

Most cases of red-green colorblindness are inherited as an X-linked recessive characteristic. Which of the following are possible if a woman, who is a carrier for colorblindness, has offspring with a male who is colorblind?

Contrast Mendel's model of heredity with the blending model. Which one is a better description of the way traits are passed from one generation to the next?

Explain the role of the human genome project and modern medicine in helping to find a cure for cystic fibrosis.

Usually, an egg cell from a human female contains

What is the probability that a person would have cystic fibrosis if one of her parents was homozygous dominant and the other was a carrier for cystic fibrosis?

Describe how you might analyze a pedigree to determine whether a particular condition is recessive or dominant, and X-linked or autosomal. For the sake of this question, ignore conditions such as multiple alleles, incomplete dominance, and other complications.

Quiz 5: Patterns of Inheritance

You learned that the phenotypic ratio of the F2 generation of a typical test cross was 3:1. The genotypic ratio was 1:2:1. Why is a different ratio seen in a dihybrid cross? What conditions must be met for these parameters to be true?

A woman with type A blood just had her first child. The child, like mother, had type A blood. What are all of the possible blood types of the father?

The defective protein that actually causes cystic fibrosis is found in

Duchenne muscular dystrophy (MD) is inherited from an X-linked recessive allele. What is the probability that a son with Duchenne MD inherited this disease from his biological father?

Explain how females with the chromosome constitution XXX are often fertile with normal intelligence and lead normal lives.

Compare and contrast the blending and particulate models of heredity.

Why do geneticists find that human genetics are rather hard to study, when compared to experimental organisms such as pea plants or fruit flies?

Most cases of red-green colorblindness are inherited as an X-linked recessive characteristic. Which of the following are possible if a woman, who is a carrier for colorblindness, has offspring with a male who is colorblind?

Contrast Mendel's model of heredity with the blending model. Which one is a better description of the way traits are passed from one generation to the next?

Explain the role of the human genome project and modern medicine in helping to find a cure for cystic fibrosis.

Usually, an egg cell from a human female contains

What is the probability that a person would have cystic fibrosis if one of her parents was homozygous dominant and the other was a carrier for cystic fibrosis?

Describe how you might analyze a pedigree to determine whether a particular condition is recessive or dominant, and X-linked or autosomal. For the sake of this question, ignore conditions such as multiple alleles, incomplete dominance, and other complications.

You learned that the phenotypic ratio of the F₂ generation of a typical test cross was 3:1. The genotypic ratio was 1:2:1. Why is a different ratio seen in a dihybrid cross? What conditions must be met for these parameters to be true?