Q: Which formula is used to calculate the recombinant frequency between two linked genes?

$$\frac{\text{Number of recombinant progeny}}{\text{Total number of progeny}}$$

Q: In a genetic cross, the degrees of freedom for a chi-square test are calculated as:

$$\text{Number of categories} - 1$$

Question 1

Which experimental technique allows scientists to pinpoint the physical location of a specific gene on a chromosome using fluorescent probes?

Accepted Answer

Fluorescence In Situ Hybridization (FISH)

Question 2

In Thomas Hunt Morgan’s experiments with Drosophila, the inheritance of white eyes in male flies provided evidence for which genetic principle?

Accepted Answer

X-linked inheritance

Question 3

A female mammal is heterozygous for a gene located on the X chromosome. Due to X-inactivation, what is the expected result in her somatic cells?

Accepted Answer

Some cells express one allele, while others express the alternate allele, creating a mosaic pattern

Question 4

Which formula is used to calculate the recombinant frequency between two linked genes?

Accepted Answer

$$\frac{	ext{Number of recombinant progeny}}{	ext{Total number of progeny}}$$

Question 5

A testcross between AaBb (heterozygote for two linked genes, 24 map units apart) and aabb yields 1200 offspring. How many are expected to have the Ab phenotype?

Accepted Answer

144

Question 6

Which chromosomal abnormality results from meiotic nondisjunction and is characterized by three copies of chromosome 21?

Accepted Answer

Down syndrome

Question 7

In the human X-Y sex determination system, which gene on the Y chromosome is critical for initiating male development?

Accepted Answer

SRY gene

Question 8

Which of the following best explains why males are more frequently affected by X-linked recessive disorders?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will cause the disorder

Question 9

Which statistical test is commonly used to determine if observed genetic ratios deviate significantly from expected Mendelian ratios?

Accepted Answer

Chi-square test

Question 10

If the calculated chi-square value for a genetic cross is less than the critical value at the chosen significance level, what is the correct interpretation?

Accepted Answer

Fail to reject the null hypothesis; the data are consistent with the expected ratio

Question 11

Which of the following is a direct consequence of crossing over during meiosis?

Accepted Answer

Genetic recombination between homologous chromosomes

Question 12

In birds, which sex determination system is used, and which sex is heterogametic?

Accepted Answer

Z-W system; females are heterogametic

Question 13

Which structure is formed when one of the X chromosomes in female mammals condenses and becomes transcriptionally inactive?

Accepted Answer

Barr body

Question 14

Which of the following best describes a linkage map?

Accepted Answer

A map showing the relative positions of genes based on recombination frequencies

Question 15

A male with the genotype XYY is most likely to exhibit which of the following characteristics?

Accepted Answer

Normal fertility and taller than average height

Question 16

Which of the following is the fundamental unit of chromatin, consisting of DNA wrapped around a core of histone proteins?

Accepted Answer

Nucleosome

Question 17

In a genetic cross, the degrees of freedom for a chi-square test are calculated as:

Accepted Answer

$$	ext{Number of categories} - 1$$

Question 18

Which real-world example illustrates the effect of X-inactivation in mammals?

Accepted Answer

Tortoiseshell cats with mosaic coat patterns

Question 19

Which of the following statements about genetic linkage is correct?

Accepted Answer

Genes located close together on the same chromosome tend to be inherited together

Question 20

Which chromosomal abnormality is characterized by a female with only one X chromosome (45, X)?

Accepted Answer

Turner syndrome

Chromosomal Basis of Inheritance and Genetic Linkage

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