Answer:
Hemophilia is a X-linked recessive disease. Tim is not correct in his thinking because he can not pass the condition to his son. Only mother can pass it to sons since they get X chromosome from the mother. Father gives Y chromosome to sons which does not carry the hemophilic gene.
Tim and Stephanie's son can be hemophilic even when neither of the parents are hemophilic. In this case, Stephanie must be a carrier i.e. heterozygous for the trait.
Tim : XHY (normal)
Stephanie : XHXh (normal but carrier)
Their children:
XH Y
XH XHXH XHY
Xh XHXh XhY
As clear by the punnett square, all the daughters will be normal (half will be carriers like Stephanie). Half of the sons will be normal (XHY) and other half will have hemophilia (XhY).
Question is incomplete i have added complete question in ask for detail section and at the end of this question.
Answer:
b. using negative feedback to decrease blood glucose levels
Explanation:
When the level of glucose increases in the blood and become higher than the normal level a negative feedback mechanism is initiated under the control of hypothalamus. which increase the metabolism of excessive glucose level present in blood and hence results in decrease or normalization of glucose level in blood.
Reference: Mayer, Jean. "Glucostatic mechanism of regulation of food intake." New England Journal of Medicine 249.1 (1953): 13-16.
Complete question
Which method best describes how an organism regulates blood glucose levels after consumption of a large meal?
a. using negative feedback to increase blood glucose levels
b. using negative feedback to decrease blood glucose levels
c. using positive feedback to increase blood glucose levels
d. using positive feedback to decrease blood glucose levels
