During the contraction of a vertebrate skeletal muscle fiber, calcium ions _____
A) break cross-bridges by acting as a cofactor in the hydrolysis of ATP
B) bind with troponin, changing its shape so that the myosin-binding sites on actin are exposed
C) transmit action potentials from the motor neuron to the muscle fiber
D) spread action potentials through the T tubules
E) re-establish the polarization of the plasma membrane following an action potential
Answer: B
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To understand past and predict future changes in populations, ecologists use three important factors. These are:
A. the population's birth rate. B. expected longevity of individuals in the population. C. the proportion of individuals in the population able to reproduce. D. the population's birth rate and the expected longevity of individuals in the population. E. the population's birth rate, the expected longevity of individuals in the population, and the proportion of individuals in the population able to reproduce.
Prokaryotic ribosomes are composed of ____
a. proteins only b. proteins and DNA c. proteins and RNA d. glycolipids and DNA e. glycolipids and RNA
Inflammation, complement proteins, and phagocytes are a part of ____ immunity
a. adaptive b. innate c. antibody-mediated d. cell-mediated e. surface barrier
Which of the following statements concerning growth and reproduction is false?
a. Growth and reproduction may occur simultaneously in living organisms. b. A living organism must reproduce to be considered alive. c. Living things may stop growing and reproducing yet still be alive. d. Normally, living organisms have the ability to grow and reproduce themselves.