Which scenario is an example of positive feedback?
a. When oxygen levels are low, the kidneys secrete erythropoietin, which stimulates the proliferation and
differentiation of red blood cells until oxygen demands are met.
b. As blood pressure increases, specialized neurons relay the change to the brainstem, which in turn, decreases
the contractility of the heart and leads to vasodilation, thereby decreasing blood pressure.
c. After an injury, chemicals released at the site of injury will activate platelets, which will in turn activate
additional platelets, and so on, until the clot has formed and the injury is no longer bleeding.
d. When stress levels are high, the hypothalamus secretes corticotropin-releasing hormone (CRH), which in turn
stimulates the secretion of adrenocorticotropic hormone (ACTH), which then triggers the release of cortisol.
Increased cortisol levels then inhibit the release of CRH and ACTH.
e. After eating, when glucose levels are high, insulin levels increase, leading to an increase in glycogen and fat
synthesis to remove excess glucose from circulation.
ANSWER: c
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An individual is constipated. They take magnesium salts to help loosen the stool. Why does this work?
A. Water moves from the intestines to the blood because the blood is hypertonic B. Water moves from the intestines to the blood because the blood is hypotonic. C. Water moves from the blood to the intestines because the blood is hypertonic D. Water moves from the blood to the intestines because the blood is hypotonic. Clarify Question · What is the key concept addressed by the question? · What type of thinking is required? Gather Content · What do you know about osmosis? What other information is related to the question? Choose Answer · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer? Reflect on Process · Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
The ability to process information from the environment _______________
A. is a trait unique to multicellular organisms B. is a trait unique to eukaryotes C. requires a brain and spinal cord D. is characteristic of all types of organisms E. is unique to primates
In males, the primary source of estrogens is the ________
A) heart B) hypothalamus C) ovaries D) adrenal cortex
What is the relationship between the degree of crossing over and the distance between two genes?
A) It is direct: as the distance decreases, the frequency of recombination increases. B) It is direct: as the distance increases, the frequency of recombination increases. C) It is indirect: as the distance increases, the frequency of recombination doubles. D) There is no correlation. E) It is indirect: as the distance decreases, the frequency of recombination doubles.