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.  Bell #8 is the zygote resulting from fertilization.          a.  Where has the non-disjunction occur?  Use cell numbers to help you explain the location of the non-disjunction.       b.  What non-disjunction syndrome does this illustration demonstrate?  How do you know?

Identify each chromosomal designations as indicative or aneuploidy, polyploid, or neither aneuploidy or polyploidy.  The chromosomal designations all apply to the chromosomal complement of human cells.

Which one of the following is suggestive of epistasis?

The roseatte spoonbill is a bird that lives in mangrove marches and captures insects with a long spoon-shaped bill.  Bill color is due to a gene that has two incompletely dominant allele.  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.      a.  What color bill do heterozygotes most likely express?      b.  Explain the reasoning/rationale behind your answer to a.

In the space provided, describe one characteristic in the expression of a polygenic trait in a population.

Suppose number of fingers and toes in the North American sasquatch is an X-linked trait represented with the letters A and a.  The dominant allele results in polydactyly, more than 5 fingers on hands and more than 5 toes on feet.  The recessive allele results in “normal” number of fingers and toes, 5 fingers on hands and 5 toes on feet.  Which of the following genotypes would result in a sasquatch with the normal number of fingers and toes?  Select all correct choices.

Which one of the following is not one of the major mechanism by which the environment may influence the expression of a gene?

Which one of the following best describe the product of a gene?

Match the allele combination with the correct term used to describe that genotype combination.

X inactivation can cause mosaicism in mammalian females.  In mosaicism, the phenotype associated with a particular X-linked gene differs in various parts of the body.  A good example is the tortoiseshell cat, which expresses orange fur in some parts of her body and black fur in other parts of her body.  Which one of the following best describe the genotype associated with a mosaicism phenotype?