A primary source of carbon for photosynthetic organisms is:
a. carbon dioxide in the atmosphere and water.
b. bicarbonate in the water.
c. nitrate in the soil.
d. dissolved phosphate in water.
e. carbonic acid in rain.
a
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Predict the expected consequence(s) of applying a toxin that blocks voltage-gated Ca2+ channels in a neuron.
A. No resting membrane potential would be observed (i.e., measures at 0 mV). B. Neuron conducts action potentials normally, but would not transmit these potentials across chemical synapses. C. The neuron would become hyperpolarized. D. A rapid increase in membrane potential at threshold voltage would not occur. E. Membrane potential would increase rapidly to peak with an action potential, but would not decrease immediately afterward.
Mammals have the most complex nervous system of all vertebrates
Indicate whether the statement is true or false
Carrier-mediated transport is necessary when
A) diffusion will not allow adequate amounts of a substance to enter the cell. B) movement into the cell is against a concentration gradient. C) the level of nutrients in nature is very low. D) nutrient concentration is very low in the environment, is higher inside of the cell, or diffusion is not possible.
Moistening and lubrication of food occurs in the
human a. mouth. b. esophagus. c. stomach. d. duodenum. e. jejunum.