When researchers calibrate the molecular clock they are
A. determining how much time it takes to accumulate a certain percentage of nucleotide changes.
B. setting the geological time scale according to the position in which the fossil was found in the rock.
C. investigating where the least common ancestor was found.
D. generalizing about the amount of time between speciations.
E. setting the geological time scale according to the position in which the fossil was found in the rock and investigating where the least common ancestor was found.
A. determining how much time it takes to accumulate a certain percentage of nucleotide changes.
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The molecular formula for glucose is C6H12O6. What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration reactions?
A) C60H120O60 B) C6H12O6 C) C60H102O51 D) C60H100O50 E) C60H111O51
The ascending and descending nerve tracts
a. are found in the gray matter of the spinal cord. b. are found in the white matter of the spinal cord. c. are covered with myelin sheaths. d. are both sensory and motor. e. all of these except "are found in the gray matter of the spinal cord"
Which hormones are produced by the hypothalamus but secreted by the posterior pituitary gland?
A. oxytocin and antidiuretic hormone. B. thyrotropin-releasing hormone and corticotropin-releasing hormone. C. prolactin and growth hormone. D. prolactin and vasopressin. E. follicle-stimulating hormone and leutenizing hormone.
Which of the following is NOT a way that bacteria benefit humans?
A. killing harmful insects B. breaking down wastes, toxins, explosives, and petrochemicals C. production of antibiotics D. production of foodstuffs such as cheese E. transferring nutrients across intestinal membranes