A 40-year-old pregnant woman is concerned about possible genetic defects in her unborn fetus. Her physician recommends prenatal testing and advises her of two methods.
Compare and contrast amniocentesis with chorionic villus sampling relative to the time each can be performed, and the relative advantages and disadvantages of each.
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Question 2) A female infant is born with several hundred oocytes, each one genetically unique. This is due to ________.
A) independent assortment and random crossover
B) recessive inheritance
C) mutation
D) chromosome deletion
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Question 3) The folk singer, Woody Guthrie, died of Huntington's chorea. One of his parents also died of this disease affecting the nervous system.
The disease usually affects carriers between 25 and 45 years of age and is inherited as a Mendelian autosomal dominant trait. Using Punnett squares, determine the probability that any of the three Guthrie offspring will have this devastating disease.
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Question 4) Is genetic diversity due entirely to inherited genes on the sex chromosomes?
A) Yes, because the female has two X chromosomes and the male has only one X chromosome.
B) Yes, because genetic diversity is due to the Y influence on the autosomes.
C) Yes, because the male has a Y chromosome.
D) No, because genetic diversity has nothing to do with the sex chromosomes but is due to crossing-over of chromosomes, independent assortment of chromosomes, and segregation of chromosomes.
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Question 5) Those characteristics that can be determined on superficial inspection of an individual are known as ________.
A) polyspermic
B) polygenic
C) genotypic
D) phenotypic
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Question 6) Parents are informed after an amniocentesis that the results show a baby who has an extra number 21 chromosome. Should there be concern and what might the problem be?
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Question 7) Recessive genes are usually expressed in humans only when ________.
A) the organism is in the embryonic stage
B) they are coding for skin color
C) they are coding for genetic diseases
D) both alleles are exactly the same, or homozygous
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Question 8) In humans, farsightedness is inherited by possession of a dominant gene. If a man who is homozygous for normal vision (aa) marries a woman who is heterozygous for farsightedness, what proportion of their children would be expected to be farsighted?
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Question 9) Dominant alleles are so called because under most circumstances they ________.
A) code for genes that are never considered lethal
B) suppress the expression of other alleles
C) code for desired traits only
D) code for most phenotypic and genotypic expressions of a trait
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Question 10) What were the genotypes of the parental ( P1 ) individuals?
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