The kidneys perform several important functions in the human body. one of these is to regulate the amount of water that makes up the liquid part of blood. if too much water is present, the kidney will increase the amount of urine produced and lower the amount of liquid water in the blood. if the amount of water is too low, the kidney will decrease the amount of urine produced in order to conserve water. a person spends several days in a hot, dry desert environment with little water available to drink. which statement best summarizes how the kidneys will function during this time? a) the amount of urine produced will increase to allow the body to eliminate heat b) the amount of urine produced will increase in order to eliminate waste products from the body c) the amount of urine produced will decrease in order to maintain the proper amount of water in the bloodstream d) the amount of urine produced will decrease because the body will not be producing waste products during this time

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

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.