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1. You are studying a species of birds that does not have X and Y chromosomes, b

ID: 199018 • Letter: 1

Question

1. You are studying a species of birds that does not have X and Y chromosomes, but instead has Z and W sex chromosomes such that males are ZZ and females are z 1A. Considering how sex determination is controlled differently by the X and Y chromosomes of Drosophila compared to humans, that the Z and W chromosomes could control sex determination in these bi please suggest two possible ways rds. 1B. To determine which of your two possible explanations for this sex determination is correct, you decide to examine the sex characteristics of individuals that have non-standard numbers of sex chromosomes-that is they have karyotypes that differ from the usual ZZ and ZW possibilities. Using the results from Drosophila and humans as a guide, please suggest which karyotypes you would consider most informative to determine how sex determination is controlled in birds. 2. You are studying a diploid species with a haploid n value of 8. A. How many total chromosomes would you expect this species to have during interphase of mitosis? B. How many total chromosomes are present at the metaphase plate of a mitotic cell. C. How many total chromatids are present at the metaphase Il plate of a cell in meiosis. D. How many total chromatids are present at the metaphase I plate of a cell in meiosis. E. How many total chromatids are present during the Leptotene phase? F. What is the n value of a cell in prophase I during meiosis? G. What is the n value of a cell in prophase II during meiosis? H. What is the n value of a cell in prophase I of mitosis? 3. What are the names of the connection points on chromatids that microtubules attach to? What structures are the other ends of the microtubules associated with?

Explanation / Answer

in humans

Mother Father

X1X2 X3Y

X1X3 X1Y X2X3 X3Y so two children would be girls and two boys the numbers are just for understanding purposes

in birds

males females

ZaZb ZcW

ZaZc ZaW ZbZc ZbZc