Question 1

Correns described that the inheritance of variegated colour on the leaves of certain plants was determined by the maternal parent only. What phenomenon does this describe?

Accepted Answer

A)  mitochondrial inheritance
B)  chloroplast inheritance
C)  genomic imprinting
D)  infectious inheritance
E)  sex-linkageF) A) and E)
G) None of the above

Question 2

Duchenne muscular dystrophy (DMD) is caused by a gene on the human X chromosome. The patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. They rarely live past their 20s. How likely is it for a woman to have this condition?

Accepted Answer

A)  Women can never have this condition.
B)  One-half of the daughters of an affected man could have this condition.
C)  One-fourth of the children of an affected father and a carrier mother could have this condition.
D)  Very rarely would a woman have this condition; the condition would be due to a chromosome error.
E)  Only if a woman is XXX could she have this condition.F) A) and E)
G) C) and E)

Question 3

An inversion in a human chromosome often results in no demonstrable phenotypic effect in the individual. What else may occur?

Accepted Answer

A)  There may be deletions later in life.
B)  Some abnormal gametes may be formed.
C)  There is an increased frequency of mutation.
D)  All inverted chromosomes are deleted.
E)  The individual is more likely to get cancer.F) A) and B)
G) All of the above

Question 4

A nonreciprocal crossover causes which of the following products?

Accepted Answer

A)  deletion only
B)  duplication only
C)  nondisjunction
D)  deletion and duplication
E)  duplication and nondisjunctionF) A) and E)
G) None of the above

Question 5

Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F₁ males will have cinnabar eyes?

Accepted Answer

A)  0%
B)  25%
C)  50%
D)  75%
E)  100%F) None of the above
G) A) and E)

Question 6

Mitochondrial DNA is primarily involved in coding for proteins needed for electron transport. Therefore, in which body systems would you expect most mitochondrial gene mutations to be exhibited?

Accepted Answer

A)  the immune system and the blood
B)  the excretory and respiratory systems
C)  the skin and senses
D)  the nervous and muscular systems
E)  the circulation systemF) None of the above
G) A) and B)

Question 7

The phenotype most commonly observed in a natural population is the

Accepted Answer

A)  wild type.
B)  parental type.
C)  recombinant type.
D)  Z-W system.
E)  F1.F) A) and C)
G) B) and E)

Question 8

Which of the following is true of aneuploidies in general?

Accepted Answer

A)  A monosomy is more frequent than a trisomy.
B)  45 X is the only known human live-born monosomy.
C)  Some human aneuploidies have selective advantage in some environments.
D)  Of all human aneuploidies, only Down syndrome is associated with mental retardation.
E)  An aneuploidy resulting in the deletion of a chromosome segment is less serious than a duplication.F) All of the above
G) A) and B)

Question 9

Abnormal chromosomes are frequently found in malignant tumours. Errors such as translocations may place a gene in close proximity to different control regions. Which of the following might then occur to make the cancer worse?

Accepted Answer

A)  an increase in nondisjunction
B)  expression of inappropriate gene products
C)  a decrease in mitotic frequency
D)  death of the cancer cells in the tumour
E)  sensitivity of the immune systemF) B) and C)
G) A) and E)

Question 10

An abnormal number of a specific chromosome is referred to as

Accepted Answer

A)  triploid.
B)  aneuploid.
C)  polyploid.
D)  recombinant.
E)  translocated.F) A) and E)
G) B) and D)

Question 11

Refer to the following information to answer the questions below.
A man who is an achondroplastic dwarf with normal vision marries a colour-blind woman of normal height. The man's father was 6 feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green colour blindness is X-linked recessive.
-They have a daughter who is a dwarf with normal colour vision. What is the probability that she is heterozygous for both genes?

Accepted Answer

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

Question 12

Which of the following statements is true of linkage?

Accepted Answer

A)  The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.
B)  The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 100%.
C)  All of the traits that Mendel studied-seed colour, pod shape, flower colour, and others-are due to genes linked on the same chromosome.
D)  Linked genes are found on different chromosomes.
E)  Crossing over occurs during prophase II of meiosis.F) A) and C)
G) B) and C)

Question 13

Calico cats are female because

Accepted Answer

A)  the males die during embryonic development.
B)  a male inherits only one of the two X-linked genes controlling hair colour.
C)  the Y chromosome has a gene blocking orange colouration.
D)  only females can have Barr bodies.
E)  multiple crossovers on the Y chromosome prevent orange pigment production.F) A) and B)
G) A) and C)

Question 14

Which of the following is known as a Philadelphia chromosome?

Accepted Answer

A)  a human chromosome 22 that has had a specific translocation
B)  a human chromosome 9 that is found only in one type of cancer
C)  an animal chromosome found primarily in the mid-Atlantic area of the United States
D)  an imprinted chromosome that always comes from the mother
E)  a chromosome found not in the nucleus but in mitochondriaF) D) and E)
G) B) and E)

Question 15

The term hemizygous refers to

Accepted Answer

A)  autosomal characteristics in diploid populations.
B)  incomplete dominance of phenotypic traits.
C)  having two different alleles on the loci of polyploidal species.
D)  X-linked characteristics expressed in mammalian males.
E)  X-linked characteristics in mammalian females resulting from Barr body silencing.F) A) and B)
G) A) and C)

Question 16

Refer to the following information to answer the questions below.
A man who is an achondroplastic dwarf with normal vision marries a colour-blind woman of normal height. The man's father was 6 feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green colour blindness is X-linked recessive.
-How many of their daughters might be expected to be colour-blind dwarfs?

Accepted Answer

A)  all
B)  none
C)  half
D)  one out of four
E)  three out of fourF) B) and C)
G) B) and E)

Question 17

What does a frequency of recombination of 50% indicate?

Accepted Answer

A)  The two genes are likely to be located on different chromosomes.
B)  All of the offspring have combinations of traits that match one of the two parents.
C)  The genes are located on sex chromosomes.
D)  Abnormal meiosis has occurred.
E)  Independent assortment is hindered.F) D) and E)
G) A) and E)

Question 18

When Thomas Hunt Morgan crossed his red-eyed F₁ generation flies to each other, the ?F₂ generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?

Accepted Answer

A)  The gene involved is on the Y chromosome.
B)  The gene involved is on the X chromosome.
C)  The gene involved is on an autosome, but only in males.
D)  Other male-specific factors influence eye colour in flies.
E)  Other female-specific factors influence eye colour in flies.F) A) and C)
G) All of the above

Question 19

A couple has a child with Down syndrome. The mother is 39 years old at the time of delivery. Which of the following is the most probable cause of the child's condition?

Accepted Answer

A)  The woman inherited this tendency from her parents.
B)  One member of the couple carried a translocation.
C)  One member of the couple underwent nondisjunction in somatic cell production.
D)  One member of the couple underwent nondisjunction in gamete production.
E)  The mother had a chromosomal duplication.F) D) and E)
G) A) and B)

Question 20

In humans, clear gender differentiation occurs, not at fertilization, but after the second month of gestation. What is the first event of this differentiation?

Accepted Answer

A)  formation of testosterone in male embryos
B)  formation of estrogens in female embryos
C)  anatomical differentiation of a penis in male embryos
D)  activation of SRY in male embryos and masculinization of the gonads
E)  activation of SRY in females and feminization of the gonadsF) B) and D)
G) B) and E)

Exam 15: The Chromosomal Basis of Inheritance

What does a frequency of recombination of 50% indicate?

Correct Answer
verified

When Thomas Hunt Morgan crossed his red-eyed F₁ generation flies to each other, the ?F₂ generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?

Correct Answer
verified

Correns described that the inheritance of variegated colour on the leaves of certain plants was determined by the maternal parent only. What phenomenon does this describe?

Correct Answer
verified

Correct Answer
verified

Which of the following is known as a Philadelphia chromosome?

Correct Answer
verified

The term hemizygous refers to

Correct Answer
verified

Mitochondrial DNA is primarily involved in coding for proteins needed for electron transport. Therefore, in which body systems would you expect most mitochondrial gene mutations to be exhibited?

Correct Answer
verified

A couple has a child with Down syndrome. The mother is 39 years old at the time of delivery. Which of the following is the most probable cause of the child's condition?

Correct Answer
verified

An abnormal number of a specific chromosome is referred to as

Correct Answer
verified

The phenotype most commonly observed in a natural population is the

Correct Answer
verified

Duchenne muscular dystrophy (DMD) is caused by a gene on the human X chromosome. The patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. They rarely live past their 20s. How likely is it for a woman to have this condition?

Correct Answer
verified

Calico cats are female because

Correct Answer
verified

Which of the following statements is true of linkage?

Correct Answer
verified

Which of the following is true of aneuploidies in general?

Correct Answer
verified

An inversion in a human chromosome often results in no demonstrable phenotypic effect in the individual. What else may occur?

Correct Answer
verified

Abnormal chromosomes are frequently found in malignant tumours. Errors such as translocations may place a gene in close proximity to different control regions. Which of the following might then occur to make the cancer worse?

Correct Answer
verified

Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F₁ males will have cinnabar eyes?

Correct Answer
verified

In humans, clear gender differentiation occurs, not at fertilization, but after the second month of gestation. What is the first event of this differentiation?

Correct Answer
verified

Correct Answer
verified

A nonreciprocal crossover causes which of the following products?

Correct Answer
verified

Exam 15: The Chromosomal Basis of Inheritance

What does a frequency of recombination of 50% indicate?

Correct AnswerverifiedShow Answer

When Thomas Hunt Morgan crossed his red-eyed F₁ generation flies to each other, the ?F₂ generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?

Correct AnswerverifiedShow Answer

Correns described that the inheritance of variegated colour on the leaves of certain plants was determined by the maternal parent only. What phenomenon does this describe?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which of the following is known as a Philadelphia chromosome?

Correct AnswerverifiedShow Answer

The term hemizygous refers to

Correct AnswerverifiedShow Answer

Mitochondrial DNA is primarily involved in coding for proteins needed for electron transport. Therefore, in which body systems would you expect most mitochondrial gene mutations to be exhibited?

Correct AnswerverifiedShow Answer

A couple has a child with Down syndrome. The mother is 39 years old at the time of delivery. Which of the following is the most probable cause of the child's condition?

Correct AnswerverifiedShow Answer

An abnormal number of a specific chromosome is referred to as

Correct AnswerverifiedShow Answer

The phenotype most commonly observed in a natural population is the

Correct AnswerverifiedShow Answer

Duchenne muscular dystrophy (DMD) is caused by a gene on the human X chromosome. The patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. They rarely live past their 20s. How likely is it for a woman to have this condition?

Correct AnswerverifiedShow Answer

Calico cats are female because

Correct AnswerverifiedShow Answer

Which of the following statements is true of linkage?

Correct AnswerverifiedShow Answer

Which of the following is true of aneuploidies in general?

Correct AnswerverifiedShow Answer

An inversion in a human chromosome often results in no demonstrable phenotypic effect in the individual. What else may occur?

Correct AnswerverifiedShow Answer

Abnormal chromosomes are frequently found in malignant tumours. Errors such as translocations may place a gene in close proximity to different control regions. Which of the following might then occur to make the cancer worse?

Correct AnswerverifiedShow Answer

Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F₁ males will have cinnabar eyes?

Correct AnswerverifiedShow Answer

In humans, clear gender differentiation occurs, not at fertilization, but after the second month of gestation. What is the first event of this differentiation?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A nonreciprocal crossover causes which of the following products?

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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