Which of the following is an example of positive feedback?
A) After eating a meal containing high glucose levels, the pancreas secretes more insulin, a hormone that lowers blood glucose levels.
B) After cutting your finger, the injured tissue releases chemicals that activate platelets in the blood. These activated platelets release chemicals to activate more platelets, leading to the formation of a blood clot.
C) An elevation in blood pressure causes heart rate to decrease, thereby causing blood pressure to decrease.
D) The secretion of the hormone TSH stimulates the thyroid gland to secrete thyroxine. Thyroxine, in turn, inhibits the secretion of TSH.
Answer: B
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In glycolysis, which of the following molecules is oxidized to form 1,3-bisphosphoglycerate?
A) 3-phosphoglycerate B) 2-phosphoglycerate C) glyceraldehyde-3-phosphate D) glucose E) glucose-6-phosphate
The problem with plastic garbage is that it ________
a. can go from storm drains to the sea only b. can harm birds and mammals when consumed only c. can last for hundreds of years in the ecosystem only d. all of the choices
The soft, fuzzy hair covering the body of a fetus in the second trimester is called
a. vernix caseosa. b. fossa ovalis. c. chorionic villus. d. lanugo. e. colostrum.
Carl Woese has controversially proposed that all three domains of life evolved from a(n) ________
A) single last unique common ancestor (LUCA) B) extremophilic archaean C) fusion of a bacterium with an archaean D) universal gene-exchange pool E) very large virus