in humans, the allele for hemophilia, h, is recessive. which is true of a woman with the genotype xhxh? a. the woman and all of
her children are hemophiliacs. b. all of her sons will inherit the allele for hemophilia. c. she is a carrier of hemophilia but does not have the condition.
The answer is <span>b. all of her sons will inherit the allele for hemophilia.</span>
Hemophilia is X-linked recessive disorder. It is known that <span>there are two X chromosomes (one from a mother and one from a father) in females and one X chromosome (from the mother) and one Y chromosomes (from the father) in males. In females, X-linked recessive disorder has the same pattern of inheritance as an autosomal recessive disorder. So, if xh is recessive and xH is dominant allele, a mother which has xhxh genotype has the condition (so, c is not the right answer). Further, if a father has no condition, thus his genotype is xHy, their daughters will be carriers but without the condition (so, the choice a could be right only if we know that the father has hemophilia too (xhy). Therefore, since the mother (xhxh) will give her x chromosome to her sons, they will all inherit the allele for hemophilia, and choice b. is the right answer.</span>
<u>Answer</u>: d. it will release chemical messengers.
The action potential, which is an electric pulse, will travel down the axon untill it reaches the synapses. At the synapses, neurotransmitters (chemical messengers) will be released by the neuron.
By cooling the heart, its need for oxygen is reduced. This allows surgeons to work on the heart for two to four hours without damaging the heart tissue.
