9. We respect Dr. Trudeau and all those earlier scientists who did the best they could within the contemporary understanding of the problem they addressed and utilizing the materials and technology they had at hand . Modernday biologists like to talk about resistance/susceptibility genes and patterns of inheritance, rather than family blood. They think about infectious disease in terms of microbes and pathogenicity, rather than speaking of bad humorsThey have identified vitamins and other nutrients that are abundant in some foodstuffs and lacking in other that are essential for optimal immune function. Without the benefit of such modern formulations, Dr. Trudeau, by a disciplined application of scientific curiosity and careful, ciever methodology, shed light on each of these concerns, light that helped to illuminate the minds of scientists who came after. Still, a look at his original paper leaves us wondering, were the rabbits genetically identical? Probably not! Why? Were they all of the same sex and age? Couldn't he have given the animals kept on short rations just a smaller amount of the same varieties of food available to the animals fed abundantly after all, there might be some important nutrient missing in potatoes. In light of the title of the paper, why not measure bacterial numbers in the rabbits on post mortem rather than just survival time ? (In a subsequent paper, he did exactly that.) Once you start critiquing an experiment from 100 years ago, or 10 years ago, or sometimes even last year, it's hard to stop. Can you think of anything else you would have changed about the Rabbit Island Experiment?

an individual’s sex (i.e., whether they are a male or female) is determined by the sex chromosomes. most people have two sex chromosomes, one that is inherited from their mother and one that is inherited from their father. typically, females have two x chromosomes (xx) and males have one x chromosome and one y chromosome (xy). conditions caused by changes (“mutations”) in genes located on the x chromosome are considered x-linked.

x-linked recessive inheritance

most x-linked conditions are recessive. this means that in a person with two x chromosomes (most females), both copies of a gene (i.e., one on each x chromosome) must have a change or mutation whereas in a person with one x chromosome (most males), only one copy of a gene must have a mutation. a female with a mutation in one copy of a gene on the x chromosome is said to be a “carrier” for an x-linked condition. a male with a mutation in a gene on the x chromosome is typically affected with the condition. because females have two copies of the x chromosome and males have only one x chromosome, x-linked recessive diseases are more common among males than females. however, x-linked recessive diseases can occur in both males and females.

for x-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the x chromosome can transmit either the x chromosome with this mutation or a “normal” x chromosome to her children. if the father is unaffected, none of her daughters will be affected and all of her daughters will be unaffected—since they will inherit at least one normal x chromosome from their father. however, each daughter will have a 50% chance of being an unaffected carrier like her mother and a 50% chance of both x chromosomes being normal.

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.