Question 1

X- linked genes in female mammals often demonstrate ______ .

Accepted Answer

A) heterochromatin formation 
B) phenotypic mosaicism 
C) incomplete dominance 
D) underrepresentation in the genome 
E) nonrecombination during meiosis 
A) heterochromatin formation 
B) phenotypic mosaicism 
C) incomplete dominance 
D) underrepresentation in the genome 
E) nonrecombination during meiosis B

Question 2

The sex of birds,some insects,and other organisms is determined by a ZW chromosomal arrangement in which the males have like sex chromosomes ZZ and females are ZW similar to XY in humans .Assume that a recessive lethal allele on the Z chromosome causes death of an embryo in birds.What sex ratio would result in the offspring if a cross were made between a male heterozygous for the lethal allele and a normal female?

Accepted Answer

A) 1:2 male to female 
B) 4:1 male to female 
C) 3:1 male to female 
D) 2:1 male to female 
E) 1:1 male to female 
A) 1:2 male to female 
B) 4:1 male to female 
C) 3:1 male to female 
D) 2:1 male to female 
E) 1:1 male to female D

Question 3

What is the ratio of male to female conceptions in a population called?

Accepted Answer

A) secondary sex ratio 
B) conception birth order number 
C) primary sex ratio 
D) anomalous gender reorder calculation 
E) gender order 
A) secondary sex ratio 
B) conception birth order number 
C) primary sex ratio 
D) anomalous gender reorder calculation 
E) gender order C

Question 4

What does the nonrecombining region of the Y contain?

Accepted Answer

A) the genes that have homologues on the X chromosome 
B) SRY 
C) the centromere 
D) A,B,and C 
E) B and C 
A) the genes that have homologues on the X chromosome 
B) SRY 
C) the centromere 
D) A,B,and C 
E) B and C

Question 5

Dosage compensation in mammals typically involves the random inactivation of one of the two X chromosomes relatively early in development.Such X chromosome inactivation often leads to phenotypic mosaicism.Assume that black fur in cats is due to the X- linked recessive gene b,whereas its dominant allele B produces yellow fur. A Bb heterozygote is a mosaic called "tortoise shell" or "calico." A mating between a black male and a calico female occurred.Give the phenotypes of the offspring.

Accepted Answer

A) calico females and yellow males 
B) all calico regardless of sex 
C) calico females,black females,yellow makes,and black males 
D) calico females,yellow females,black males,and yellow males 
E) all black regardless of sex 
A) calico females and yellow males 
B) all calico regardless of sex 
C) calico females,black females,yellow makes,and black males 
D) calico females,yellow females,black males,and yellow males 
E) all black regardless of sex

Question 6

A small part of the human Y chromosome contains the gene that is responsible for determining maleness.What is the name of this gene?

Accepted Answer

A) SRY 
B) Xist 
C) NRY 
D) Dax 
E) medulla 
A) SRY 
B) Xist 
C) NRY 
D) Dax 
E) medulla

Question 7

Give the sex of the following Drosophila assuming that the autosomes are present in the normal number.XO; XY; XXY.Answers are in order respectively .

Accepted Answer

A) male; female; female 
B) female; male; male 
C) male; male; male 
D) female; male; female 
E) male; male; female 
A) male; female; female 
B) female; male; male 
C) male; male; male 
D) female; male; female 
E) male; male; female

Question 8

Jacobs syndrome in humans,which is manifested by a higher than average stature and potential behavioral problems,is caused by which chromosomal condition?

Accepted Answer

A) 45,X 
B) 47,XYY 
C) triploidy 
D) 47,XXY 
E) 47,21+ 
A) 45,X 
B) 47,XYY 
C) triploidy 
D) 47,XXY 
E) 47,21+

Question 9

The Lygaeus mode of sex determination is the _ .

Accepted Answer

A) hermaphroditic scheme 
B) scheme based on single translocations in the X chromosome 
C) XX/XO scheme 
D) XY/XX scheme 
E) XO/YY scheme 
A) hermaphroditic scheme 
B) scheme based on single translocations in the X chromosome 
C) XX/XO scheme 
D) XY/XX scheme 
E) XO/YY scheme

Question 10

Where is the general location of a Barr body?

Accepted Answer

A) adjacent to the Y chromosome 
B) in the nucleolus 
C) attached to the other X chromosome 
D) attached to the nuclear envelope 
E) stuck in a nuclear pore 
A) adjacent to the Y chromosome 
B) in the nucleolus 
C) attached to the other X chromosome 
D) attached to the nuclear envelope 
E) stuck in a nuclear pore

Question 11

Assuming a normal number of autosomes,what would be the sex of the following: XXY mouse,XXY Drosophila?

Accepted Answer

A) male and female,respectively 
B) both neuter 
C) female and female,respectively 
D) male and male,respectively 
E) female and male,respectively 
A) male and female,respectively 
B) both neuter 
C) female and female,respectively 
D) male and male,respectively 
E) female and male,respectively

Question 12

In humans,the male is the ______sex.

Accepted Answer

A) heterogametic 
B) homogametic 
C) monogametic 
D) homomorphic 
E) heteromorphic 
A) heterogametic 
B) homogametic 
C) monogametic 
D) homomorphic 
E) heteromorphic

Question 13

In Drosophila,an individual female fly was observed to be of the XXY chromosome complement normal autosomal complement and to have white eyes as contrasted with the normal red eye color of wild type.
-The female's father had red eyes,and the mother had white eyes.Knowing that white eyes are X- linked and recessive,present an explanation for the genetic and chromosomal constitution of the XXY,white- eyed individual.

Accepted Answer

A) nondisjunction in meiosis I of mother and meiosis II of father 
B) nondisjunction in meiosis II of mother 
C) nondisjunction in either meiosis I or meiosis II of the mother 
D) nondisjunction in meiosis I of mother 
E) nondisjunction in meiosis II of father 
A) nondisjunction in meiosis I of mother and meiosis II of father 
B) nondisjunction in meiosis II of mother 
C) nondisjunction in either meiosis I or meiosis II of the mother 
D) nondisjunction in meiosis I of mother 
E) nondisjunction in meiosis II of father

Question 14

Which of the following human genetic conditions is missing a chromosome?

Accepted Answer

A) Jacob syndrome 
B) Klinefelter syndrome 
C) XXXX syndrome 
D) Down's syndrome 
E) Turner syndrome 
A) Jacob syndrome 
B) Klinefelter syndrome 
C) XXXX syndrome 
D) Down's syndrome 
E) Turner syndrome

Question 15

Which of the following karyotypes would lead to male characteristics in humans?

Accepted Answer

A) XO 
B) XYY 
C) XXY 
D) XO and XYY 
E) XXY and XYY 
A) XO 
B) XYY 
C) XXY 
D) XO and XYY 
E) XXY and XYY

Question 16

Which of the following statements is false?

Accepted Answer

A) An individual with Klinefelter syndrome generally has one Barr body. 
B) Dosage compensation is accomplished in humans by inactivation of the Y chromosome. 
C) An individual with Turner Syndrome has no Barr bodies. 
D) In a cell with X chromosomes lacking the XIC,there is still X inactivation. 
E) A typical XX human female has one Barr body. 
A) An individual with Klinefelter syndrome generally has one Barr body. 
B) Dosage compensation is accomplished in humans by inactivation of the Y chromosome. 
C) An individual with Turner Syndrome has no Barr bodies. 
D) In a cell with X chromosomes lacking the XIC,there is still X inactivation. 
E) A typical XX human female has one Barr body.

Question 17

In ____,sex is determined by the ratio of the number of X chromosomes to the number of haploid sets of autosomes.

Accepted Answer

A) humans 
B) Drosophila 
C) 
C) elegans 
D) reptiles 
E) Drosophila and C.elegans 
A) humans 
B) Drosophila 
C) 
C) elegans 
D) reptiles 
E) Drosophila and C.elegans

Question 18

For an individual with the XXY chromosomal composition,the expected number of Barr bodies in interphase cells is______.

Accepted Answer

A) two 
B) one 
C) three 
D) variable 
E) zero 
A) two 
B) one 
C) three 
D) variable 
E) zero

Question 19

A recessive gene for red- green color blindness is located on the X chromosome in humans.Assume that a woman with normal vision her father is color blind)marries a color- blind male.What is the likelihood that this couple's first son will be color blind?

Accepted Answer

A) 75% 
B) 0% 
C) 50% 
D) 100% 
E) 25% 
A) 75% 
B) 0% 
C) 50% 
D) 100% 
E) 25%

Question 20

Which of the following statements is true regarding Drosophila?

Accepted Answer

A) The ratio of X to Y chromosomes determines fly sex. 
B) The Y chromosome determines male flies. 
C) The ratio of autosomes to fly Y and X chromosomes determines fly sex. 
D) The Y chromosome plays no role on fly sex determination but does contain genes for fly reproduction. 
E) The Y chromosome plays no role in fly sex determination or fly reproduction. 
A) The ratio of X to Y chromosomes determines fly sex. 
B) The Y chromosome determines male flies. 
C) The ratio of autosomes to fly Y and X chromosomes determines fly sex. 
D) The Y chromosome plays no role on fly sex determination but does contain genes for fly reproduction. 
E) The Y chromosome plays no role in fly sex determination or fly reproduction.

Exam 7: Sex Determination and Sex Chromosomes

X- linked genes in female mammals often demonstrate ______ .

What is the ratio of male to female conceptions in a population called?

What does the nonrecombining region of the Y contain?

A small part of the human Y chromosome contains the gene that is responsible for determining maleness.What is the name of this gene?

Give the sex of the following Drosophila assuming that the autosomes are present in the normal number.XO; XY; XXY.Answers are in order respectively .

Jacobs syndrome in humans,which is manifested by a higher than average stature and potential behavioral problems,is caused by which chromosomal condition?

The Lygaeus mode of sex determination is the _ .

Where is the general location of a Barr body?

Assuming a normal number of autosomes,what would be the sex of the following: XXY mouse,XXY Drosophila?

In humans,the male is the ______sex.

Which of the following human genetic conditions is missing a chromosome?

Which of the following karyotypes would lead to male characteristics in humans?

Which of the following statements is false?

In ____,sex is determined by the ratio of the number of X chromosomes to the number of haploid sets of autosomes.

For an individual with the XXY chromosomal composition,the expected number of Barr bodies in interphase cells is______.

A recessive gene for red- green color blindness is located on the X chromosome in humans.Assume that a woman with normal vision her father is color blind)marries a color- blind male.What is the likelihood that this couple's first son will be color blind?

Which of the following statements is true regarding Drosophila?

Introduction to Genetics

Mitosis and Meiosis

Mendelian Genetics

Extensions of Mendelian Genetics

Chromosome Mapping in Eukaryotes

Genetic Analysis and Mapping in Bacteria and Bacteriophages

Chromosome Mutations: Variation in Number and Arrangement

Extranuclear Inheritance

DNA Structure and Analysis

DNA Replication and Recombination

DNA Organization in Chromosomes

The Genetic Code and Transcription

Translation and Proteins

Gene Mutation,dna Repair,and Transposition

Regulation of Gene Expression in Bacteria

Transcriptional Regulation in Eukaryotes

Post-Transcriptional Regulation in Eukaryotes

Epigenetic Regulation in Eukaryotes

Recombinant Dna Technology

Genomic Analysis

Applications of Genetic Engineering and Biotechnology

Developmental Genetics

Cancer Genetics

Quantitative Genetics and Multifactorial Traits

Population and Evolutionary Genetics

CRISPR and Genomic Editing

DNA Forensics

Genomics and Precision Medicine

Genetically Modified Foods

Gene Therapy

Advances in Neurogenetics: The Study of Huntington Disease

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