A free radical will "steal" what particle from a stable molecule?
a. a proton
b. a neutron
c. an atom
d. an electron
e. a positron
D
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Which organism provides a good example of sexual dimorphism?
a. Sage grouse b. Hangingfly c. Sparrows d. Fruit flies e. Fiddler crabs
Organelles do all of the following EXCEPT
a. manufacture proteins. b. sustain internal microenvironments. c. control import and export of materials. d. transport substances. e. all of the above functions are performed by organelles.
Choose the correct order (1-5) of increasing complexity/organization.
A. (1) tissues, (2) organs, (3) organ systems, (4) cells, (5) organism B. (1) tissues, (2) organ systems, (3) cells, (4) organs, (5) organism C. (1) organism, (2) organ systems, (3) organs, (4) tissues, (5) cells D. (1) cells, (2) organ systems, (3) tissues, (4) organs, (5) organism E. (1) cells, (2) tissues, (3) organs, (4) organ systems, (5) organism
Acetylcholine is a signaling molecule that elicits responses from heart muscle cells, salivary gland cells, and skeletal muscle cells. Which of the following statements is false?
(a) Heart muscle cells decrease their rate and force of contraction when they receive acetylcholine, whereas skeletal muscle cells contract. (b) Heart muscle cells, salivary gland cells, and skeletal muscle cells all express an acetylcholine receptor that belongs to the transmitter-gated ion channel family. (c) Active acetylcholine receptors on salivary gland cells and heart muscle cells activate different intracellular signaling pathways. (d) Heart muscle cells, salivary gland cells, and skeletal muscle cells all respond to acetylcholine within minutes of receiving the signal.