Exam 5: The Chromosomal Basis Of Mendelism

In Drosophila,X^w denotes a white eyed allele and X⁺denotes the red-eyed allele.An X^wX^wY female is crossed with an X⁺Y male.What are the possible progeny genotypes?

Down Syndrome occurs when there is an extra chromosome #21.Such individuals therefore have 47 chromosomes.Assume that a mating occurs between a female with Down Syndrome and a normal male.Assuming normal disjunction during meiosis,what percentage of offspring would be expected to have Down Syndrome?

Sexual dimorphism can be determined by:

Assume that coat color in cats is an X-linked trait.Briefly explain why only females can exhibit a combination of coat colors (i.e.Calico)whereas normal XY males can only exhibit one

An X chromosome that has been inactivated becomes a(an)___________ in female mammals.

Which of the following is a mechanism that can compensate for an abnormal number of sex chromosomes in an individual? 1.Each X-linked gene could work twice as hard in males as it does in females 2)One copy of each X-linked gene could be inactivated in females 3)Each X-linked gene could work half as hard in females as it does in males

A woman,with normal vision whose father was colorblind mates with a man who has normal vision.What are the chances that she will have a son who is colorblind?

A color blind male mates with woman who has normal vision.The woman has no history of colorblindness in her family.What percentage of their sons are expected to be colorblind?

A researcher crosses a white eyed female Drosophila with a red eyed male.Knowing that the gene for eye color is sex linked,he expects to observe only red-eyed females and white eyed males in the progeny.However,he observes that while most of the progeny are as expected,a small percentage of the females have white eyes.Explain what may have occurred to cause this result.

X and Y chromosomes are known as:

When chromosomes fail to separate during meiosis,thereby producing an egg with two X chromosomes or an egg with no X chromosome at all,this event is referred to as:

Which of the following is the part of the Y chromosome that is critical for normal male development?

An organism's standard chromosome number (n)is known as the ________ number.

In some animal species,like the grasshopper,sex is determined by:

In Drosophila the Y chromosome is not required for male sex determination.However,it is required for :

Cells that contain two of each of the chromosomes in a set are known as:

In humans the Y chromosome carries _________ genes than the X chromosome.

A diffuse network of thin and loosely coiled chromosomes is referred to as:

A Drosophila is determined to have the genotype XO.What can you determine about this individual based upon this information?

Which of the following is an X-linked disorder in human beings?