In order for a muscle contraction to occur, cross-bridges must form between which one of the following structures within a muscle cell?
A) the plasma membrane and the sarcoplasmic reticulum
B) troponin and tropomyosin
C) calcium and tropomyosin
D) acetylcholine and muscle cell receptors
E) actin and myosin
E
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How did Darwin refer to changes in a population over many generations?
a. genetic drift b. descent with modification c. differential reproduction d. mutations
What is the underlying molecular cause of Crohn’s disease?
A. B cells are mutated and do not release antibodies. B. Receptor proteins are mutated and do not detect bacteria properly. C. Helper T cells are inactivated. D. Mucus is not released from epithelial tissues. E. More than one of these in combination.
Why does glucose appear in the urine of a diabetic?
A. The carriers for glucose reabsorption reach their maximum rate of transport. B. The ascending limb of the loop of Henle secretes glucose into the urine. C. No glucose is filtered into the glomerular filtrate. D. The volume of urine is too great to filter. E. The kidneys produce glucose in diabetes.
While focusing on a microscope on high power, a student crushed the coverslip. The student probably
a. shut the light off b. turned up the light intensity c. rotated the eyepiece d. used the coarse adjustment