Answer the questions and e-mail your answers to me.

• 1) Which of the following chromosomal alterations would you expect to
  have the most drastic consequences?
  

  inversion
  duplication
  translocation
  deletion
  a and b are equally the most serious
• 2) Tay-Sachs disease runs in Rebecca's family. On a family pedigree,
  she saw a half-darkened circle. This represented
  

  a male with Tay-Sachs.
  a female with Tay-Sachs.
  a carrier male.
  a carrier female.
  a male of unknown genotype.
• 3) On a pedigree tracing the inheritance of PKU, a horizontal line
  joins a black square and a half-black circle. What fraction of this
  couple's children would you expect to suffer from PKU?
  

  none
  1/4
  1/2
  3/4
  all
• 4) Michelle and Keith are apparently normal, but their daughter was
  born with alkaptonuria, an inherited metabolic disorder. If
  alkaptonuria is like most human hereditary disorders, the
  probability of their next child being born with alkaptonuria is
  

  0.
  1/4.
  1/2.
  2/3.
  3/4.
• 5) Several inherited disorders are much more common in close-knit
  religious communities, such as the Amish, than in the general
  population. This is at least partly due to the fact that
  

  these people are more likely to marry relatives
  shared environmental conditions can increase mutation rate
  modern medical care is not widely available
  medical care methods pass the disorders on
  families are large in these communities
• 6) In a cross between two heterozygotes (Aa), the F2 generation will be
  

  in the ratio 1:3 heterozygous to homozygous
  all heterozygous
  in the ratio 1:1 homozygous to heterozygous
  all homozygous
  in the ratio 1:3 homozygous to heterozygous
• 7) You set up an experiment in which you breed two populations of true-
  breeding pea plants. The first true-breeding population has yellow
  round seeds and the second has green wrinkled seeds. All of the F1
  plants yield yellow round seeds. When you self fertilize the F1 the
  F2 generation yields a mixture of yellow round, yellow wrinkled,
  green round and green wrinkled seeds. What does this tell you about
  the alleles for seed color and shape ?
  

  the recessive alleles are always expressed
  the alleles are on different chromosomes
  the two alleles segregate during gamete production
  four different genes control flower shape and color
  both genes are on the same chromosome
• 8) You cross a true-breeding red-flowered snapdragon with a true-
  breeding white-flowered one. All of the F1 are pink. What does this
  say about the parent traits?
  

  red and white are codominant
  red is dominant
  both red and white are recessive
  red and white show incomplete dominance
  pink is dominant, while red and white are recessive
• 9) While on a field trip in the jungle you find a new species of mouse.
  You catch a pair and take them back to the lab. In mice, black coat
  color, B, is dominant to brown b, yet the female mouse gives rise to
  a large litter in which 9 of the offspring were black, 3 were brown
  and 4 were white. You conclude that
  

  a new mutation has occurred in the mice
  this is an example of polygenic inheritance
  there must be epistasis influencing coat color
  the coat color alleles are codominant
  the coat color alleles are incompletely dominant
• 10) A new breed of domestic cat, the American Curl Cat, has unusual
  curled-back ears. When the owners of Shulamith, the foundation cat
  from which the breed arose, crossed her with a normal straight-eared
  domestic cat in each of her litters roughly half of the kittens had
  curled ears. When both parents are curl cats, all the kittens have
  curled ears. What does this tell you about the curled-ear trait?
  

  curled ears and straight ears are codominant traits
  curled ears and straight ears are show incomplete dominance
  straight ears are dominant
  curled-ears are dominant
  curled ears are recessive
• 11) John and Jane are planning a family, but since each has a brother
  who has sickle cell anemia, they are concerned that their children
  may develop sickle-cell disease. Neither John, Jane nor their
  respective parents have the disease. They consult a genetic
  counselor who tells them
  

  there is small chance their children will have sickle cell
  all of their children will have sickle-cell disease
  1/4 of their children could have sickle cell-disease
  no children could have sickle cell, but tests are needed
  you can't tell if their children may have sickle cell
• 12) In people with sickle cell disease the red blood cells breakdown,
  clump, and clog the blood vessels. The broken cells accumulate in
  the spleen. Among other things this leads to physical weakness,
  heart failure, pain, brain damage and spleen damage. Affected
  individuals become paralyzed and can develop rheumatism, pneumonia
  and other diseases and kidney failure. This is an example of
  

  the polygenic nature of sickle cell disease
  the pleiotropic effects of the sickle cell allele
  epistasis between the sickle cell allele and an enzyme gene
  infectious organisms acting on the sickle cell allele
  side effects of the drugs used to cure sickle-cell disease
• 13) Huntingdon's disease is an example of a genetic disorder caused by
  

  a late-acting lethal dominant allele
  a non-lethal dominant allele.
  a late acting recessive allele.
  homozygous recessive alleles.
  multiple alleles.
• 14) The most common phenotype in a natural population is referred to as
  the
  

  genotype.
  wild type
  autosome.
  mutant phenotype.
  locus.
• 15) Human males are much more likely to be have hemophilia (a failure of
  blood to clot properly) than human females. This is the case because
  

  hemophilia is contagious & men are more susceptible
  the gene for hemophilia is carried on the Y chromosome.
  hemophilia is carried on the autosomes.
  hemophilia is the wild type.
  the gene for hemophilia is sex-linked.
• 16) In a particular species of mammal black hair (B) is dominant to
  green hair (b) and red eyes (R) are dominant to white eyes (r). If a
  BbRr individual is mated with a bbrr individual the expected
  phenotypic ratio of the offspring is 1 black-red : 1 black-white: 1
  green-red : 1 green-white. However, when you mate these individuals
  you find that the phenotypic ratio of the offspring is 6 black-red :
  1 black-white : 1 green-red : 6 green-white. What could account for
  this difference?
  

  Green-haired individuals have higher prenatal mortality
  hair and eye color genes are on different chromosomes
  The results did not take genetic recombination into account
  The genes for both traits are carried on the autosomes
  The genes for hair color and eye color are linked.
• 17) In the preceding problem, the observed distribution of offspring
  was: black-red 1,070; black-white 177 ;green-red 180; green-
  white1072. Based on this data, what is the recombination frequency?
  

  86 percent
  7
  17 percent
  14 percent
  30 percent
• 18) A linkage map
  

  orders genes on chromosomes based on recombination frequency
  can only be constructed for sex chromosomes.
  orders genes on chromosomes based on their location
  shows the actual order and spacing of genes on a chromosome
  predicts the probability of have a male or female child
• 19) What is the probability that a male will inherit an X-linked
  recessive gene from his father?
  

  0
  25 percent
  50 percent
  75 percent
  100 percent
• 20) Duchenne muscular dystrophy is caused by a sex-linked recessive
  allele. Its victims are almost invariably boys, who usually die
  before the age of 20. Why is this disorder almost never seen in
  girls?
  

  Sex-linked traits are never seen in girls.
  The allele is carried on the Y chromosome.
  Nondisjunction occurs in males but not in females.
  Girls must have two copies of the gene to express it
  A sex-linked allele cannot be passed from mother to daughter
• 21) Which of the following is correct with regard to aneuploidy?
  

  inversion
  2n + 1
  All aneuploid individuals die before birth.
  4n
  it only involves the autosomes.
• 22) If a fragment of a chromosome breaks off and then reattaches to the
  original chromosome but in the reverse direction, the resulting
  chromosomal abnormality is called
  

  a deletion.
  an inversion.
  a translocation.
  a nondisjunction.
  polyploidy.
• 23) Why are individuals with an extra chromosome 21, which causes Down
  syndrome, more numerous than individuals with an extra chromosome 3
  or chromosome 16?
  

  There are probably more genes on chromosome 21
  Chromosome 21 is a sex chromosome and 3 and 16 are not.
  Down syndrome is not more common, just more serious.
  Extra copies of the other chromosomes are probably fatal.
  Nondisjunction of 3 and 16 probably occur more freequently
• 24) Each cell in an individual with Down syndrome contains ____
  chromosomes.
  

  3
  22
  24
  45
  47
• 25) Disorders involving unusual numbers of sex chromosomes show that
  maleness is caused by the
  

  presence of an X chromosome.
  presence of a Y chromosome.
  absence of an X chromosome.
  absence of a Y chromosome.
  absence of an X chromosome and presence of a Y chromosome.
• 26) A particular allele can have different effects if it was inherited
  from a male rather than a female. This phenomenon is known as
  

  extranuclear inheritance.
  aneuploidy.
  sex-linkage.
  Prader-Willi syndrome.
  genome imprinting.
• 27) Human mitochondria
  

  are inherited as an X-linked trait.
  are all inherited from the father.
  have linear DNA.
  do not contain DNA.
  are all inherited from the mother.