Let's take the example of the gray kangaroo (Macropus fuliginosus) whose ploidy is 8 and the sexual determinism of this species is carried out according to the XY mode. From a male kangaroo: a) Draw the karyotype of this individual, obtained by stopping division at metaphase. Your drawing should include: a. All maternal and paternal chromosomes involved (different colors) b. An example of autosome and heterochromosome c. An example of homologous chromosome, sister chromatid and centromere. d. The total number of chromosomes in a metaphase kangaroo cell. e. A sentence to explain the difference between the terms gene and allele that might apply to this species. N Page 3 / 4

In Drosophila melanogaster, a normal individual has 8 chromosomes. The species is diploid, having two sets of 4 chromosomes each. on rare occasions, an abnormal fruit fly can be produced with 12 chromosomes, having three sets of 4 chromosomes each. True/False: Such a fly is euploid. True False

In fruit flies, chromosomal crossing over does not occur in meiosis in males, whereas crossing over does occur in meiosis in females. In fruit flies that are heterozygous at many genes (i.e. many maternal and paternal versions of the genes differ), at what stage would cells no longer be heterozygous for any gene during the process of meiosis? a)After the second meiotic division in males, and after the first meiotic division in females. b)After the second meiotic division in both males and females. c)After the first meiotic division in both males and females. d)After the first meiotic division in males, and after the second meiotic division in females.

Based on the attached image, identify the stage at which each cell is in and draw an animal cell with a diploid chromosome number of 6. Indicate maternally- & paternally-derived chromosomes as red and blue, respectively, in your diagram. You do not need to indicate any crossing over. Be sure to include any of the indicated labels.

Which of the following statements is true? Select one: a. Nondisjunction during anaphase I or anaphase II will have no effect on the gametes formed. b. More gametes will be affected if nondisjunction occurs during anaphase I than if nondisjunction occurs during anaphase II. c. More gametes will be affected if nondisjunction occurs during anaphase II than if nondisjunction occurs during anaphase I. d. Nondisjunction during anaphase I or anaphase II will have the same effect.

The Oregon creeping vole, Microtus oregoni, has a very unusual meiosis?. In this rodent, males are XY, while females are XØ (that is, females have only a single X chromosome). During female meiosis, eggs that receive no maternal X chromosome do not mature, so females only produce eggs with exactly one X chromosome. As chromosome content is unchanged from generation to generation, M. oregoni males (who are XY) must deliberately nondisjoin their sex chromosomes. 1a) What types of sperm would M. oregoni have to produce (considering only their sex chromosome content) so that progeny get the right chromosomes? Remember, no inviable combinations are normally produced. 1b) Draw a Punnett square for the sex chromosomes in a M. oregoni mating, with the gametes that are actually produced. Indicate the sex of each offspring. 1c) From which parent do M. oregoni get their X chromosomes? Circle one. Mom Only Random Mom or Dad Dad Only

A diploid (2n) trihybrid individual with the genotype EeFfGg can make eight genetically different gametes.  Loci E/e and F/f are on chromosome 1 and locus G/g is on chromosome 2. Explain how a gamete containing the alleles e, f and g may be produced by meiosis. Refer specifically to meiotic events occurring during Prophase I, Metaphase I, Anaphase I and Anaphase II. (NB: remember to refer to the organism above).

Assume that the diploid number of a certain species is four chromosomes, two large and two small (2n=4). a)  Of the following figures, which represents a 3n (triploid) cell in mitotic metaphase? b)  For each of the wrong answers from part (a) above, explain briefly why it cannot represent a triploid cell in mitotic metaphase.