What does PTH stimulate when blood calcium levels are low?
a. excretion of calcium from the kidneys
b. excretion of calcium from the intestines
c. osteoclasts
d. osteoblasts
c. osteoclasts
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Type III survivorship curves reflect ____
a. high juvenile mortality b. low juvenile mortality c. high survivorship d. relatively constant mortality e. high adult mortality
"H zones" in skeletal muscle are composed of
a. discs to which thin filaments are anchored. b. stacked thick filaments along with parts of thin filaments that overlap both ends. c. thin filaments but no thick filaments. d. thick filaments but no thin filaments. e. discs to which thick filaments are anchored.
Which is false regarding passive transport?
a. It depends on concentration or electrical gradients. b. It involves weak binding between solute and protein. c. It requires an energy input. d. It depends on protein shape change. e. None of these are false.
Four million years ago, horses were rather small compared to today's horses and had relatively stocky bodies with a straight shoulder and thick neck. This statement is an illustration of which biological concept?
A. development B. evolution C. reproduction D. metabolism E. homeostasis