Exam 5: Patterns of Inheritance

Which of the following statements is true?

A person with the genotype XXY will be a ___________ with _________ syndrome and have ________ chromosomes in each cell.

Compare and contrast the blending and particulate models of heredity.

Pedigrees are

Usually, an egg cell from a human female contains

Different forms of a gene are known as

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?

The genetic makeup of a particular trait in an individual is its

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?

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?

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

The length of monkey flower leaves is inherited as an incomplete dominant trait. When long leaves are crossed with short leaves a third phenotype, intermediate leaves, is produced. A plant breeder crosses two monkey flowers. The resultant offspring are 58 intermediate and 52 short-leafed plants. What are the phenotypes of the parent monkey flowers? Explain your answer.

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

Mendel determined that tall pea plants were dominant to short pea plants. Cross a homozygous short pea plant with a heterozygous tall pea plant. Which of the following is the phenotypic ratio of the offspring?

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?

An organism with two copies of the same allele is said to be

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?

An allele is