Capillaries are the narrowest elements in the blood transport system of animals. they connect the arteries (the vessels that carry blood away from the heart) to the veins (the vessels that carry blood back to the heart). they are the place where the chemicals that the blood is carrying are taken from source regions (lungs for air, intestines for food, glands for hormones) and delivered to the cells that need them. they are pretty small—about 5 µm in diameter. one of the interesting questions about this process is: how do oxygen molecules know where to go? for example, wikipedia says that red blood cells "take up oxygen in the lungs or gills and release it while squeezing through the body's capillaries." in order to consider this let's make an oversimplified model in which oxygen diffuses into the blood stream in the lungs, is carried by fluid flow out to the cells where it diffuses out. (in reality, the oxygen is bound to hemoglobin, carried, and released, but the beginning and end processes are as described here.)
fick's law tells us how a concentration difference drives flow:
j = −dδn/δx.
if the membrane in the alveolus (parts a and b) is 7 nm thick, and the diffusion constant, d, for oxygen through the membrane is 6 ✕ 10^−3(µm)2/s, calculate the rate of flow through the alveolar membrane. give your answer to two significant figures. (show your work)

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.

i believe it would be c: tons.

her next move would be to use agarose gel electrophoresis to separate the dna molecules of varying length and create a dna fingerprint.