Chapter 9: Meiosis

1.	The gibbon has 44 chromosomes per diploid set and the siamang has 50 chromosomes per diploid set. In the 1970s a chance mating between a male gibbon and a siamang female produced a viable offspring. Predict how many chromosomes were observed in the somatic cells of the offspring. Do you predict that this individual would be able to form viable gametes? Why or why not?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
2.	Meiosis results in a reassortment of maternal and paternal chromosomes. If n 3 for a given organism, there are 8 different combinations of paternal and maternal chromosomes. If no crossing over occurs, what is the probability that a gamete will receive only paternal chromosomes?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
3.	The data in the following table concern human fetuses and infants with various types of trisomy. The leftmost column indicates the extra chromosome in each case. (For example, the number 21 in the next-to-last row of this column indicates trisomy-21, which causes Down syndrome.) Note that the researchers were able to ascertain whether the gamete responsible for the trisomy came from the mother or the father. In many cases they were also able to determine whether the error occurred during meiosis I or meiosis II (if this point was unclear, the trisomy is recorded as "I or II"). o What general conclusions can you draw from these data? o Note that far more data were collected on trisomy-21 (Down syndrome) than on any other trisomy. Does this mean that nondisjunction of chromosome 21 occurs more often than nondisjunction of other chromosomes? Or could other factors influence the number of trisomy-21 fetuses or infants that were available for study?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.