Which of the following is an example of positive feedback?
A) A rise in body temperature stimulates sweat. This causes the body to cool down to normal temp.
B) Eating a sugary donut raises blood sugar. This stimulates the pancreas to release insulin.
C) Your blood pressure falls below normal, so the nervous system increases heart rate to bring blood pressure back to a normal range.
D) During childbirth, increasing levels of oxytocin hormone is released to increase the strength of uterine muscle contractions.
Answer: D) During childbirth, increasing levels of oxytocin hormone is released to increase the strength of uterine muscle contractions.
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Use the following study to answer the following question(s): A researcher applies varying amounts of fertilizer (0, 2, 4, 8, 10 units) to 50 potted tomato plants. All other variables that may affect the outcome (watering, temperature, sunlight, plant size, etc.) are kept the same from pot to pot. At the end of the growing season, the tomatoes grown on each plant are weighed to determine which fertilizer level produced the largest tomato yield.Is the study presented above a controlled experiment?
A. Yes, because many pots were used. B. No, because the experiment was done only once. C. No, because several different amounts of fertilizers were used, not just one amount. D. Yes, because only the amount of fertilizer was changed, everything else was kept the same.
HIV studies revealed that it is closely related to
A. smallpox virus. B. ebola virus. C. herpes virus. D. a chimpanzee virus. E. mad cow disease.
All EXCEPT which one of the following are
the reasons for the rapid population explosion of humans? a. increases in carrying capacity b. expansion into new habitats c. removal of limiting factors d. reproduction occurring earlier in the life cycle e. none of these
Lack of which element can lead to goiter?
a. iron b. iodine c. calcium d. zinc e. magnesium