Cytogenetics Practice Problems

By — McGraw-Hill Professional
Updated on Aug 23, 2011

Review the following concepts if needed:


Vocabulary   For each of the following definitions, give the appropriate term and spell it correctly. Terms are single words unless indicated otherwise.

  1. A cell or organism containing three sets of chromosomes.
  2. A cell or organism produced by doubling the chromosome number of an interspecific hybrid.
  3. Any variation in chromosome number that does not involve whole sets of chromosomes.
  4. A cell or organism having a genomic formula 2n – 1.
  5. An adjective applicable to a giant chromosome consisting of hundreds of chromatid strands.
  6. Exchange of pieces between two nonhomologous chromosomes. (Two words.)
  7. Altered phenotypic expression of a gene as a consequence of movement from its normal location. (Two words.)
  8. Achromosomal aberration that, with the help of crossing over within the aberration, can lead to "bridge and fragment" formation. (Two words.)
  9. Phenotypic expression of a recessive gene as a consequence of loss of a chromosomal segment bearing the corresponding dominant allele.
  10. The arrangement of the somatic chromosome complement (karyotype) of a cell in groups of homologous pairs.

Multiple-Choice Questions   Choose the one best answer.

  1. A treatment often used to induce polyploidy experimentally in plants is   (a) X-rays   (b) gibberellic acid   (c) colchicine   (d) acridine dyes   (e) azothioprene
  2. A mechanism that can cause a gene to move from one linkage group to another is   (a) translocation   (b) inversion   (c) crossing over   (d) duplication   (e) dosage compensation
  3. If during synapsis a certain kind of abnormal chromosome is always forced to bulge away from its normal homologue, the abnormality is classified as   (a) an inversion   (b) a duplication   (c) an isochromosome   (d) a deficiency   (e) none of the above
  4. If four chromosomes synapse into a cross-shaped configuration during meiotic prophase, the organism is heterozygous for a   (a) pericentric inversion   (b) deletion   (c) translocation   (d) paracentric inversion   (e) none of the above
  5. A segment of chromosome may be protected from recombination by   (a) an inversion   (b) a translocation   (c) balanced lethals   (d) more than one of the above   (e) all of the above
  6. A person with Klinefelter syndrome is considered to be   (a) monosomic   (b) triploid   (c) trisomic   (d) deletion heterozygote   (e) none of the above
  7. Given a normal chromosome with segments labeled C123456 (C = centromere), a homologue containing an inversion including regions 3–5, and a single two-strand crossover between regions 4 and 5; then the acentric fragment present during first meiotic anaphase is   (a) 63456   (b) 12344321   (c) 65521   (d) 654321   (e) none of the above
  8. Pseudodominance may be observed in heterozygotes for   (a) a deletion   (b) a duplication   (c) a paracentric inversion   (d) a reciprocal translocation   (e) more than one of the above
  9. The most easily recognized characteristic of an inversion heterozygote in plants is   (a) gigantism   (b) semisterility   (c) a cross-shaped chromosome configuration during meiosis   (d) pseudodominance   (e) none of the above
  10. If the garden pea has 14 chromosomes in its diploid complement, how many double trisomics could theoretically exist?   (a) 6   (b) 9   (c) 16   (d) 21   (e) none of the above. (Hint: See formula (2.1).]



  1. triploid
  2. allotetraploid (amphidiploid)
  3. aneuploidy
  4. monosomic
  5. polytene
  6. reciprocal translocation
  7. position effect
  8. paracentric inversion
  9. pseudodominance
  10. idiogram

Multiple-Choice Questions

  1. c
  2. a
  3. b
  4. c
  5. e
  6. c
  7. a
  8. a
  9. b
  10. d
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