18.  The diagram below shows spermatogenesis (on the left) a…

18.  The diagram below shows spermatogenesis (on the left) and oogenesis (on the right) followed by a fertilization event.  The numbered circles are cells.  The long purple bars in the cells are X chromosomes while the short blue bars in the cells are Y chromosomes.  Cell #8 is the zygote resulting from fertilization.          a.  Where has the non-disjunction occurred?  Use the number to the upper left of the cell to help you explain the location of the non-disjunction.       b.  What non-disjunction syndrome does this illustration demonstrate?  How do you know?

13.  The roseatte spoonbill is a bird that lives in mangrove…

13.  The roseatte spoonbill is a bird that lives in mangrove marshes and captures insects with a long spoon-shaped bill.  Bill color is due to a gene that has two incompletely dominant alleles.  Individuals that are homozygous for one allele have a black bill.  Individuals that are homozygous for the other allele have a bill that is almost white. What color bill will heterozygous individuals most likely express?  Explain the reasoning/rationale behind your answer.