Difficulty in swallowing can be found in a patient with damaged cranial nerve IX or glossopharyngeal nerve. The nerve is located in brain stem near the other cranial nerve. Glossopharyngeal nerve has a role in the sensory and motoric of the pharynx and tongue/glosus. Other cranial nerves like nervus V(trigeminal), X(vagus) and XII(hypoglossal) also have a few role in pharyngeal phase of swallowing.
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When a few individuals are isolated from the rest of the population and can have very different gene frequencies, it is called the Founder Effect. The founder effect is a type of genetic drift in which a small population is isolated. Due to this isolation, the population may have different gene frequencies than the rest of the larger population.
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B is the correct answer :))) took bio last year
The new population that experienced natural selection is now better fit or more adapted to the environment than the old population