Q: Which equation correctly predicts the expected number of Barr bodies in a human cell?

$$\text{Number of Barr bodies} = \text{Number of X chromosomes} - 1$$

Question 1

Which of the following best describes the mechanism of sex determination in humans?

Accepted Answer

The presence or absence of the Y chromosome determines sex.

Question 2

In the great lubber grasshopper, what is the chromosomal composition of a sperm that can produce a male offspring?

Accepted Answer

11 autosomes and a Y chromosome

Question 3

What is the primary genetic determinant of maleness in humans?

Accepted Answer

The SRY gene on the Y chromosome

Question 4

Which equation correctly predicts the expected number of Barr bodies in a human cell?

Accepted Answer

$$	ext{Number of Barr bodies} = 	ext{Number of X chromosomes} - 1$$

Question 5

A calico cat is an example of which genetic phenomenon?

Accepted Answer

Dosage compensation and female mosaicism due to X-inactivation

Question 6

In Drosophila melanogaster, the gene for white eyes is located on the X chromosome. If a white-eyed male is crossed with a wild-type red-eyed female, what will be the phenotype of the F1 offspring?

Accepted Answer

All offspring will have red eyes

Question 7

Which term describes the condition in which males have only one allele for X-linked genes?

Accepted Answer

Hemizygosity

Question 8

What is the biological problem solved by dosage compensation in mammals?

Accepted Answer

Ensuring equal expression of X-linked genes in males and females

Question 9

Which of the following is true regarding gametogenesis in humans?

Accepted Answer

Spermatogenesis produces four sperm from each primary spermatocyte

Question 10

A human with the karyotype 47,XXY is expected to have how many Barr bodies per cell?

Accepted Answer

1

Question 11

Which of the following statements about sex determination in birds is correct?

Accepted Answer

Females are heterogametic (ZW)

Question 12

In Drosophila, what is the expected phenotypic ratio of red-eyed to white-eyed males in the F2 generation when a white-eyed male is crossed with a wild-type red-eyed female?

Accepted Answer

$$1:1$$

Question 13

Which of the following is a consequence of X-inactivation in female mammals?

Accepted Answer

Females are mosaics for X-linked gene expression

Question 14

Which genetic event provided compelling evidence for the chromosome theory of inheritance in Drosophila?

Accepted Answer

The correlation of specific phenotypes with the movement of chromosomes during meiosis

Question 15

What is the function of pseudoautosomal regions (PARs) on human sex chromosomes?

Accepted Answer

They enable pairing of X and Y chromosomes during meiosis I

Question 16

Which of the following karyotypes is associated with Turner syndrome in humans?

Accepted Answer

45,X

Question 17

In a cross between a female Drosophila with genotype $$X^wX^w$$ and a male with genotype $$X^wY$$, what is the expected phenotype of the offspring?

Accepted Answer

All offspring will have white eyes

Question 18

Which of the following best explains why calico males are rare?

Accepted Answer

Calico coloration requires the presence of two X chromosomes, which is rare in males (XXY)

Question 19

Which process in human oogenesis is completed only after fertilization?

Accepted Answer

Meiosis II

Question 20

Which of the following is true about sex-limited traits?

Accepted Answer

They affect structures or processes found only in one sex

Chromosome Theory of Inheritance, Sex Determination, and Sex Chromosome Linkage

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