What happens when an impulse reaches the end of an axon that is attached to skeletal muscle?
What will be an ideal response?
When an action potential reaches the end of the axon, Ca++ flows into this presynaptic cell. This causes the synaptic vesicle to approach the membrane and dump its contents, acetylcholine, into the synaptic cleft. Acetylcholine binds to receptors on the muscle cell's plasma membrane, which affects muscle permeability. Na+ flows into the muscle. This causes an action potential in the muscle, which leads to contraction.
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Alternation of heteromorphic generations
(a) is found only in the bryophytes. (b) is common to all land plants. (c) is typical of most green algae. (d) occurs in the liverworts but not mosses.
Mutations like bithorax, in which a second pair of wings develops in the place of halteres, give clues to the evolutionary origin of differentiated structures. What inferences might you draw from bithorax, or antennapedia?
What will be an ideal response?
The disadvantage of batch fermentations, as opposed to continuous feed systems, is that
A. the end product is not as pure as the product made by the continuous feed process. B. new substrate must be added to the fermentor continuously for the fermentation to continue. C. there is a limit to the amount of product formed since all materials are added to the fermentor at the beginning. D. it is small scale production of a product.
Asexual reproduction __________.
A. is limited to plants B. produces offspring that always look exactly like the parent C. leads to a loss of genetic material D. can produce offspring genetically identical to the one single parent