11.
The image is a line with markers A through E along it at given distances. A and B are 8 apart. B and C are 12 apart. C and D are 3 apart. D and E are 5 apart.The figure represents a Drosophila linkage map for genes A-E. The numbers between the gene loci are the relative map units between each gene. Based on the linkage map, which two genes are most likely to segregate together?
  1. A and B
  2. B and C
  3. C and D
  4. D and E
12
A test cross was made between true-breeding EEWW flies and eeww flies. The resulting F1 generation was then crossed with eeww flies. 100 offspring in the F2 generation were examined, and it was discovered that the E and W genes were not linked. Which is the correct genotype of the F2 offspring if the genes were linked and if the genes were not linked?
  1. Linked: 50% EeWw and 50% eeww; not linked: 25% EeWw, 25%, Eeww 25% eeWw, and 25% eeww
  2. Linked: 25% Eeww, 50% eeWw; not linked: parental genotypes EeWw and eeww.
  3. Linked genotypes (EeWw and eeww) and recombinant genotypes (Eeww and eeWw) in the F2 generation are nearly the same irrespective of their linkage.
  4. Linked: mostly with parental genotypes, Eeww and eeWw; unlinked: 25% EeWw and eeww with 75% Eeww and eeWw.
13.
A cross was made with true-breeding AABB flies and true-breeding aabb flies. The resulting F1 generation was then crossed with true-breeding aabb flies. Based on the linkage map, which of the following F2 generation genotype ratios is most likely to be observed?
  1. Number Observed: AaBb (46), Aabb (4), aaBb (4), Aabb (46)
  2. Number Observed: AaBb (4), Aabb (46), aaBb (46), Aabb (4)
  3. Number Observed: AaBb (25), Aabb (25), aaBb (25), Aabb (25)
  4. Number Observed: AaBb (50), Aabb (0), aaBb (0), Aabb (50)
14

In this micrograph of a male human karyotype, an extra copy of the X chromosome is present, in addition to a Y chromosome. All other chromosomes show the normal diploid state with 2 copies

Which of the following symptoms is most likely associated with the disorder shown in the karyotype?

  1. lethality
  2. infertility
  3. heart and bleeding defects
  4. short stature and stunted growth
15

In this micrograph of a male human karyotype, an extra copy of the X chromosome is present, in addition to a Y chromosome. All other chromosomes show the normal diploid state with 2 copies

Choose the correct option amongst the following that describes the disorder shown in the karyotype and the social, ethical or medical issue related to the disorder.

  1. Down syndrome (47 XY +21) causes intellectual disability, vision problems, congenital heart disease, and susceptibility to cancer. Healthcare providers often do not discuss the positive aspects of raising a child with Down syndrome and often provide out of date information.
  2. Klinefelter syndrome (47 XY +21) causes intellectual disability, vision problems, congenital heart disease, and susceptibility to cancer. Arguments are often made against abortion of an affected fetus.
  3. Klinefelter syndrome (47 XXY) causes sterility and reduced testosterone production. Arguments are often made against informing insurance companies about a diagnosis of this disease.
  4. Down syndrome (47 XXY) causes sterility and lower testosterone production. Arguments are often made against informing insurance companies about a diagnosis of this disease.
16

A horizontal line is divided proportionally into 4 sections by 5 vertical lines, one at each end and 3 in the middle. The 5 vertical lines are labelled R, S, T, U and V. The 4 sections have values from left to right of 6, 11, 2 and 4.

Which of the following gene orders is the most likely outcome of an inversion mutation in the chromosome shown?

  1. RSTUV
  2. RRSTUV
  3. RSUV
  4. RTSUV
17

This illustration shows nondisjunction that occurs during meiosis 1 and meiosis 2. Nondisjunction during meiosis 1 occurs when a homologous pair fails to separate, and results in two gametes with n + 1 chromosomes, and two gametes with n − 1 chromosomes. Nondisjunction during meiosis 2 would occur when sister chromatids fail to separate, and results in one gamete with n + 1 chromosomes, one gamete with n − 1 chromosomes, and two normal gametes.

With the help the diagram given, choose the most appropriate statement describing nondisjunction and its genetic consequences.

  1. Nondisjunction occurs when a homologous pair is unable to separate during meiosis I, resulting in the formation of gametes containing n+1 and n-1 chromosomes. This is called aneuploidy.
  2. Nondisjunction occurs due to the inability of sister chromatids to separate during meiosis II, resulting in the formation of gametes containing n+1 and n-1 chromosomes. This results in heart and bleeding defects.
  3. Nondisjunction is the failure of homologous chromosomes to separate during meiosis I or failure of sister chromatids to separate during meiosis II. This results in aneuploid gametes.
  4. Nondisjunction occurs when a pair of homologous chromosomes fails to segregate during meiosis II resulting in the formation of gametes containing n+1, n-1, or n numbers of chromosomes. This results in abnormal growth patterns.
18
If the effects of Klinefelter syndrome are compared to the effects of Down Syndrome, this disorder is ______.
  1. more severe than Down syndrome, due to gene deletions in this syndrome
  2. more severe than Down syndrome, due to trisomy in Klinefelter syndrome
  3. less severe than Down syndrome, due to monosomy in Down Syndrome
  4. less severe than Down syndrome, due to X-inactivation in this disorder