1. Two mothers give birth to sons at the same time in a busy urban hospital. The son of couple #1 is afflicted with hemophilia A. Neither parent has the disease. Couple #2 has a normal son despite the fact that the father has hemophilia A. The two couples sue the hospital in court claiming that a careless doctor swapped their babies at birth. You appear in court as an expert witness. What do you tell the jury? Make a diagram(s) that you can submit to the jury.

2. Meiosis results in a reassortment of maternal and paternal chromosomes. If 2n =6 for a given organism. (a) What are the possible numbers of different combinations of paternal and maternal chromosomes. (b) If no crossing over occurs, what is the probability that a gamete will receive only paternal chromosomes?

3. You are interested in using bacteria to bioremediation at an old chemical plant and convert toxic compounds toluene and benzene into harmless compounds. You discover bacteria that are able to tolerate high levels of toluene and benzene, and you suspect that this is due to the ability of the bacteria to break these compounds into less-toxic products. If this true, these toluene- and benzene-resistant strains will be valuable for cleaning up toxic sites. (a) How could you find out whether these bacteria are metabolizing toluene as a source of carbon compounds? (b) Assuming that the bacteria do have an enzymatic pathway to break down toluene, would you predict that genes involved are constitutively expressed under positive control or under negative control? WHY?