Too much calcium in the bloodstream, a condition called hypercalcemia, can be very dangerous. The thyroid gland releases a hormone, calcitonin, when calcium is too high. How does calcitonin lower calcium levels in the blood?
A) It reduces osteoclast activity and increases osteoblast activity.
B) It increases osteoclast activity and reduces osteoblast activity.
C) It reduces both osteoclast and osteoblast activity.
D) It increases both osteoclast and osteoblast activity.
A
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Many metabolic pathways are ultimately concerned with ATP; either with the generation of ATP, or with the requirement of ATP for that pathway to function. Why is ATP so important to metabolism?
A. Hydrolysis of ATP is used to drive exergonic reactions B. Hydrolysis of the bond between adenine and ribose in ATP is commonly used to release energy that can be used to drive other cellular reactions C. The phosphate groups of ATP are held together by unstable bonds that can be broken to release energy D. ATP is a protein that serves as the energy currency of cells
Which of the following is NOT correct regarding host defenses?
A) First line of defense blocks portals of entry. B) Second line of defense include inflammation and phagocytosis. C) Third line of defense is lymphocyte-dependent and specific. D) Fourth line of defense provides long-term immunity.
The head bobbing of lizards is a visual mating signal
Indicate whether the statement is true or false
What condition is caused by a dominant allele of a single gene?
A) Huntington disease B) Down syndrome C) color blindness D) Turner syndrome E) sickle-cell anemia